Who Must Install CO Detectors in California, and by When?

Last verified: August 24, 2026

California carbon monoxide detector laws require approved alarms in dwelling units that contain a fuel-burning appliance, fireplace, or attached garage under Health and Safety Code Section 17926. The California carbon monoxide detector statute applies statewide to homes, rentals, and many hotel or short-term units, while the California Residential Code sets placement, power, and interconnection rules for new construction and permit-driven work. The section number for that code changed recently and most published guidance has not caught up: the 2025 CRC, Title 24 Part 2.5, took effect on 1 January 2026 and is built on the 2024 International Residential Code, which moved carbon monoxide alarms from Section R315 to Section R311 and reassigned R315 to sleeping lofts. Anyone still working from a CRC R315 reference is reading a section about lofts. Under the 2022 CRC, which governed until the end of 2025, R315 was correct. In practice, owners should document installation near sleeping areas and on each level, keep service records for inspections and lease turnovers, and verify both the local amendments and the code edition in force before final occupancy decisions.

The statute sets three deadlines and they have all passed, which is why California is a retrofit state rather than a new-construction one. Section 17926(a) required devices in existing single-family dwellings by 1 July 2011, in all other existing dwelling units by 1 January 2013, and in hotels and motels by 1 January 2017. Devices must be approved and listed by the State Fire Marshal under Section 13263, so a unit that carries an alarm bought outside California can still be non-compliant.

Enforcement is lighter than the retrofit scope suggests. A violation is an infraction with a maximum fine of $200 for each offence, and the owner gets a 30-day notice to correct before it can be imposed. That 30 days is worth keeping apart from the other 30-day clock a California tenant will meet, the presumption of reasonableness under Civil Code 1942(b), which runs from the tenant's notice to the landlord and does a different job for a different party.

Key Takeaways

CO detector requirements for California
Applies to homes?	Yes
Applies to rentals?	Yes
Applies to hotels/STRs?	Yes
Applies to schools?	Yes, under a condition
Applies to workplaces?	No

Schools and workplaces

Schools: it depends, and the test is one you can apply to the building itself. California legislated schools separately, and the statute it passed binds a state official rather than a school. Education Code Article 7 was added by AB 56 of 2013 and runs to two sections. Section 32080 does one thing: it borrows the meaning of "fossil fuel" from Health and Safety Code Section 13262. Section 32081(a) then directs the State Fire Marshal, by 1 July 2015, to propose standards to the California Building Standards Commission for its next triennial cycle, and it fixes what those proposed standards must require: a device in a public or private school building where three things hold together, that the building was constructed pursuant to the 2016 California Building Standards Code or a later edition, that it is used for educational purposes for kindergarten or grades 1 to 12, and that it has a fossil fuel burning furnace inside it. Read the direction before acting on it. Nothing in Article 7 tells a school to install anything; the installation duty arrives through the building standards the section made the Fire Marshal propose. Section 32081(b) handles the older building and settles it in one word: a school built before the 2016 code "is encouraged to have a carbon monoxide device installed", which is the word the statute chose over "shall". The code that carries the duty is California Code of Regulations Title 24 Parts 2 and 9 at Section 915, whose classroom limb reaches Group E occupancies and Group I-4 on the ordinary trigger conditions. Those two groups then part company over what the detector has to do. The model text at Section 915.2.3 is written for Group E alone: detectors in classrooms, with alarm signals "automatically transmitted to an on-site location that is staffed by school personnel", excepting a Group E occupancy with an occupant load of 30 or less. Group I-4 is day care and is nowhere in it. So a California school over that occupant load owes a monitored path to a staffed office and a California day care centre reached by the same Section 915 owes detectors and no transmission, which is a difference in running cost rather than in placement. Stated from the model text because California's own rendering of 915.2.3 in Title 24 could not be read on 2026-08-24; every route tried served Chapter 9 truncated before Section 915. Health and Safety Code 17926, the instrument that answers a California home or hotel, is written around dwelling units intended for human occupancy and does not describe a classroom.

Workplaces: California places no carbon monoxide detection duty on an office, shop or other workplace. Federal and state occupational rules set an exposure limit for carbon monoxide in air; they do not require a detector to be installed, and this row is about installation. California two instruments are both aimed elsewhere. Health and Safety Code 17926 requires devices in "dwelling units intended for human occupancy", and Section 13262(b) defines that term by listing a lodging house, dormitory, hotel and motel, so the statute is residential and lodging and reaches no place of work. The same subdivision then removes public ownership from even that: the term "does not mean a property owned or leased by the state, the Regents of the University of California, or a local governmental agency". California Code of Regulations Title 24 Parts 2 and 9 carry Section 915, whose occupancy list is Group I and R occupancies and classrooms in Group E occupancies, with no Group B, F, M or S. Education Code Article 7 is a school provision and not an installation duty at all: 32080 defines a term and 32081 directs the State Fire Marshal to propose building standards. Neither names a workplace.

When Are CO Alarms Required?

Buildings with fuel-burning appliances
Buildings with attached garages
New construction
When building permits are required
CO alarms generally not required in an all-electric dwelling with no fireplace and a detached garage.
Compliance deadlines referenced in common guidance: July 1, 2011 (existing single-family dwellings) and January 1, 2013 (other existing dwelling units).

Where to Install CO Alarms

Outside each sleeping area in the immediate vicinity of bedrooms (e.g., hallway).
On each level/story of the dwelling unit, including basements.
In each bedroom containing (or opening to a bathroom containing) a fuel-burning appliance.

For detailed placement guidance beyond legal requirements, see where to place carbon monoxide detectors.

Device Requirements

Device must be approved/listed by the California Office of the State Fire Marshal (SFM).
CO alarms listed to ANSI/UL 2034; CO detectors listed to ANSI/UL 2075 (or successor standards).
In new construction/when required by code: hardwired to building power with battery backup; interconnected when multiple alarms are installed.
Battery-powered or plug-in with battery backup may be allowed in certain existing-dwelling retrofit scenarios where running wiring is not feasible (per code exceptions).
Combination smoke/CO alarms are permitted if listed/approved and provide distinct alarms for smoke vs CO.

Landlord and Tenant Responsibilities

Landlord: Install required CO devices and have them working at the time the tenant takes possession. May enter the unit (per Civil Code Section 1954) to install, repair, test, and maintain CO devices. Correct reported deficiencies. Provision: HSC 17926(a) through (c), with the listing requirement at HSC 13263.

Tenant: Notify the owner/agent if the tenant becomes aware of an inoperable or deficient CO device. Provision: HSC 17926(a) through (c), with the listing requirement at HSC 13263.

Some local building guidance addresses owner testing/maintenance duties for detectors in hotels/motels/lodging houses; verify applicability for your occupancy type and jurisdiction.

Full California landlord and tenant carbon monoxide duties, with citations

Enforcement

Enforced by: Local enforcement agency / building and fire code officials (varies by jurisdiction).

Enforcement typically occurs:

During building inspections for new construction and permitted alterations/repairs/additions (retrofit triggers at CRC Section R311 under the 2025 edition in force since 1 January 2026, and at CRC Section R315 under the 2022 edition that preceded it).
After a local enforcement notice to correct (statute provides a notice-and-cure step before fines).

Enforcement and inspection practices vary by city/county; state statute provides the baseline requirement for existing dwellings with specified CO sources.

What a Tenant Can Do in California

When a carbon monoxide alarm stops working in a rented home in California, these are the five routes a tenant can take and where each one comes from.

"Via general law" means the California carbon monoxide statute itself is silent and the remedy comes from the state's landlord-tenant law instead. The remedy is available even though the alarm rule does not contain it.

Tenant remedies for a defective carbon monoxide alarm in California, with the citation or the body of law searched for each.
Rent withholding	Via general lawCal. Civ. Code 1942.4. The statute does not hand the tenant a right to withhold. It disables the landlord instead: once a housing inspector has served written notice and the condition has stood unabated for 35 days without good cause, the landlord may not demand rent, collect rent, raise it, or serve a three-day notice to pay or quit. The defence that lets a tenant stop paying is judicial, from Green v. Superior Court (1974) 10 Cal.3d 616, which held breach of the implied warranty of habitability may be raised in an unlawful detainer.
Repair and deduct	Via general lawCal. Civ. Code 1942(a). Capped at one month's rent per repair and available no more than twice in any 12-month period. Self-help, with no court involvement, which makes it a materially stronger remedy than the court-supervised versions in Ohio or the absent one in North Carolina.
Right to end the lease	Via general lawCal. Civ. Code 1942(a). The same subsection offers vacating as the alternative to repairing: the tenant may vacate and is then discharged from further payment of rent. It is an election, not an escalation, so a tenant who repairs and deducts has spent that month's remedy instead.
Notice the tenant must give	Yes, in the CO ruleCal. Health & Safety Code 17926.1. The CO act itself makes the tenant responsible for notifying the owner of an inoperable or deficient device, requires the owner to correct what is reported, and states that an owner who received no notice is not in violation. Notice is therefore the trigger rather than a formality. Neither that section nor Civ. Code 1942(a) sets a minimum notice length or a waiting period, so there is no statutory number for this column.
Landlord cure period	Via general law, 30 daysCal. Civ. Code 1942(b). Thirty days is a presumption rather than a deadline: a tenant who acts to repair and deduct after the 30th day following notice is presumed to have acted after a reasonable time, and a shorter period can be reasonable for a hazard. A second 30-day clock runs elsewhere and should not be confused with it. Under Health and Safety Code 17926(c)(2) an owner must receive a 30-day notice to correct before the $200 infraction fine can be assessed. The two run from different events and protect different parties.

Applies to every row above:California's carbon monoxide duty sits in the Health and Safety Code, which reaches dwelling units with a fossil-fuel burning appliance, a fireplace or an attached garage. That act creates one tenant-facing mechanism, the notice duty in 17926.1, and no remedy beyond it, so the other four columns come from Civil Code 1941 through 1942.4. Two limits travel with those: the repair-and-deduct route is unavailable where the tenant caused the condition (Civ. Code 1942(c), referring to 1929 and 1941.2), and 17926.1 expressly excuses an owner who never received notice, which makes a written, dated report worth more in California than the general statute alone suggests.

Remedies last checked 2026-08-03. Compare California with the other states.

What California Requires in Lodging

The California carbon monoxide requirement reaches hotels and short-term rentals.

Hotels already standing: covered too. The California requirement reaches an existing hotel and not only one being built.

Operator duty: Must install CO devices in hotel and motel dwelling units intended for human occupancy with a fossil fuel burning heater or appliance, fireplace, or attached garage (HSC Section 17926(a)(2), compliance deadline 1 January 2017; "hotel, motel" is named in the Section 13262(b) definition). Placement follows the standard for the occupancy, which Section 17926(b) makes explicit and which for a guest room is Section 915 of the California Building Code rather than the Residential Code: 915.2.2 puts the detection inside the sleeping unit unless neither the room nor its attached bathroom holds a fuel-burning appliance and no forced-air furnace serves it. Section 915.1 carries the statutory bridge in its own text, requiring detection in all existing Group R buildings pursuant to Section 17926.

Full California hotel and short-term rental requirements

Penalties for Non-Compliance

Violation is an infraction punishable by a maximum fine of $200 per offense; the owner must generally receive a 30-day notice to correct before a fine is imposed.

Health and Safety Code 17926(c)(1) for the $200 infraction and (c)(2) for the 30-day notice to correct, read from the code itself at leginfo.legislature.ca.gov rather than from the city guidance and bill text an earlier version of this note relied on. 17926(a)(2) is what brings lodging in, requiring devices in existing hotel and motel dwelling units on or before 1 January 2017. Note 17926(d) separately caps at actual damages not exceeding $100 and provides that no transfer is invalidated by noncompliance, which is a different figure from the infraction and is easy to confuse with it. Its second sentence, which most reproductions of the subdivision omit, reads "This subdivision is not intended to affect any duties, rights, or remedies otherwise available at law", so the $100 bounds a claim founded on 17926 itself and not a habitability or negligence claim alongside it. Read in full from leginfo on 2026-08-23 and confirmed against the FindLaw mirror.

Additional Notes

The state statute ties required devices to the presence of fossil-fuel burning appliances/fireplaces or an attached garage; code provisions govern technical installation details.
Local jurisdictions may adopt additional or stricter requirements.
Hotels and motels are explicitly covered under Health and Safety Code Section 17926(a)(2).

Local Rules That Differ From State Law

At least one California municipality sets CO requirements that go beyond the statewide rule. Where your property sits decides which applies, and the stricter one governs.

San Francisco

Read this one before relying on a city web page, because San Francisco is where the trap is. The fire department publishes guidance stating that the city requires carbon monoxide alarms in all dwelling units. No section of the fire code as adopted in San Francisco says that, and department guidance is not an ordinance. The city's rendering of Section 915 and of the existing-building provision at Section 1103.9 matches Los Angeles word for word across all twelve occurrences of the term, which is what a clean adoption looks like. So the operative requirement in San Francisco is Health and Safety Code 17926 and its fuel-burning appliance, fireplace or attached garage triggers, not the broader duty the guidance describes. The same trap retired a Columbus claim earlier in this dataset. A landlord who installs on the guidance is doing no harm; one who relies on it to say a neighbour must install has nothing to cite.

San Francisco Fire Code as adopted, Sections 915 and 1103.9, against San Francisco Fire Department published guidance Checked 2026-08-04.

San Jose

San Jose puts carbon monoxide alarms into housing that Health and Safety Code 17926 does not reach, because that statute keys on a fuel-burning appliance, a fireplace or an attached garage and these buildings have none. Section 5.09.410 governs emergency sleeping cabins and requires each one to carry at least one smoke alarm and one carbon monoxide alarm, with a dual-function device accepted for both. Read that against subsection A of the same section, which forbids the cabins any plumbing or gas service, and subsection F, which requires electrical heating equipment. The cabin is all-electric and detached, the state exemption fits it exactly, and San Jose requires the alarm regardless. The city drafted the contrast deliberately, because Section 5.09.430 covers other emergency housing and there the duty is conditional, arising only where the building has fuel-burning appliances. Two further sections, 5.09.320 for emergency bridge housing and 5.12.330 for homeless shelters, hand carbon monoxide alarms to the authority having jurisdiction to determine and enforce.

San Jose Municipal Code Sections 5.09.410(H) and 5.09.430(F), with Sections 5.09.320 and 5.12.330 (Ordinances 30199 and 30969) Checked 2026-08-03.

Los Angeles

Nothing on top of the state rule. LAMC Section 57.915 adopts California Fire Code Section 915 without touching it, and the city's rendering of Section 915 and of the existing-building carbon monoxide provision at Section 1103.9 matches San Francisco's word for word across all twelve occurrences of the term. An Angeleno owner therefore has one instrument to read, Health and Safety Code 17926, and no city layer above it.

Los Angeles Municipal Code Section 57.915, adopting California Fire Code Section 915 Checked 2026-08-04.

San Diego

Nothing on top of the state rule, and San Diego says so in terms rather than by silence, which is a stronger result than a search returning nothing. The city's own document host still refuses connections, so this was read from the Internet Archive capture of 22 April 2026. Section 145.0103 adopts the 2025 California Building Code by reference. Section 145.0104 then lists what San Diego leaves out, and the list runs to administration, two roof-assembly classes and plumbing; carbon monoxide detection sits in Chapter 9 of that code and survives the cut. The confirmation comes from the one document that would carry a local change: Division 9 of Article 5 exists to hold San Diego's modifications to Chapter 9, and its Section 145.0901 reads that Chapter 9 is adopted by reference without change. A page written to record amendments and recording none beats a search that returns nothing. The city's fire code divisions on building services and on existing buildings, and the designation and scope division of its housing code, carry no carbon monoxide provision either.

San Diego Municipal Code Sections 145.0103, 145.0104 and 145.0901, Article 5 Division 9 Checked 2026-08-04.

What was checked:Four jurisdictions were read: San Jose, Los Angeles, San Francisco and San Diego, each recorded below as its own entry rather than summarised here. One is a real divergence, one is a published-guidance trap worth knowing about before you rely on a city web page, and two are clean confirmations that the state rule is the only rule. California's county building departments and the smaller cities that write their own short-term rental rules were not searched.

Local sweep last reviewed 2026-08-04.

Official Sources & References

California Health and Safety Code Section 17926, carbon monoxide devices in dwelling units , HSC 17926(a) through (c), with the listing requirement at HSC 13263 (state code, accessed 2026-08-12)
The operative statute, which this page rested on without citing. Read in full on 2026-08-12 by two extraction paths that agree. Subsection (a) obliges an owner of a dwelling unit intended for human occupancy to install a carbon monoxide device approved and listed by the State Fire Marshal under Section 13263, where the unit has a fossil-fuel appliance, a fireplace or an attached garage, and sets three deadlines that have all passed: existing single-family dwellings by 1 July 2011, all other existing dwelling units by 1 January 2013, and hotels and motels by 1 January 2017. Subsection (b) ties number and placement to the building standards for new construction of that occupancy, or to the manufacturer's instructions. Subsection (c) makes a violation an infraction with a maximum fine of two hundred dollars ($200) for each offense, after a 30-day notice to correct. The three dates, the $200 and the State Fire Marshal listing had no source on this page before.
California Senate Bill 183 (Chapter 19, Statutes of 2010) - Carbon Monoxide Poisoning Prevention Act (adds H&S Code Sections 13260-13263 and 17926-17926.2) (state code, accessed 2026-02-16)
Chaptered bill text establishing statewide CO device requirements, responsibilities, and penalties.
City of Agoura Hills - Carbon Monoxide Detectors Q&A (citing H&S Code Sections 13262, 17926, 17926.1, 17926.2) (agency guidance, accessed 2026-02-16)
Government handout quoting statutory sections; includes UL standards, placement, landlord/tenant duties, and penalties.
Contra Costa County - Residential Smoke & Carbon Monoxide Alarms (based on 2022 CBC/CRC/CFC; CRC R315) (building code, accessed 2026-02-16)
Official local building inspection guidance summarizing 2022 California code requirements including power/interconnection and locations.
City of Milpitas - Carbon Monoxide (CO) Alarms/Detection handout (Aug 1, 2024) (agency guidance, accessed 2026-02-16)
Official city handout summarizing deadlines, triggers, and installation locations; links to SFM listing categories.

Disclaimer: This page explains the law as it stood on August 24, 2026. It is general information, not legal advice, and reading it creates no attorney-client relationship. Requirements vary by city, county and building type, and statutes and codes are amended: confirm the current text with the issuing authority before acting on it. Each requirement here cites the instrument it comes from, so you can check it at source.

Frequently Asked Questions

Are carbon monoxide detectors required in California homes and rentals?

Yes. California carbon monoxide detector requirements come from the Carbon Monoxide Poisoning Prevention Act, codified in Health and Safety Code Section 17926. Homes and rental units generally need alarms when the unit has a fuel-burning appliance, a fireplace, or an attached garage. Hotels and many short-term units are also covered by the same statutory framework. For new construction and permit-triggered work, the California Residential Code adds technical rules on wiring, interconnection, and placement. Check which section number applies before following any guidance you find, including guidance from a city. The 2025 CRC took effect on 1 January 2026 and puts carbon monoxide alarms at Section R311, where the 2022 CRC put them at Section R315. R315 in the current edition is the sleeping loft section, so a stale reference does not fail visibly, it sends the reader to the wrong subject instead. Local jurisdictions may enforce stricter details, so use city or county guidance for those while confirming the edition it was written against.

When is a California home usually exempt from the CO alarm requirement?

Health and Safety Code Section 17926 ties the mandate to three physical conditions in the dwelling unit, a fossil-fuel burning heater or appliance, a fireplace, or an attached garage. A fully electric home with no fireplace and a detached garage meets none of them and sits outside the statute. Two things narrow that exemption in practice. A city may require more, as San Jose does for emergency sleeping cabins that the state exemption fits exactly. And the exemption is about the unit's own conditions, so in a building where combustion equipment sits in a shared space the question is worth asking again rather than answered from the meter. Detached garage means detached: a garage sharing a wall or a ceiling with the dwelling is an attached garage for this purpose.

Where should CO alarms be installed under California code?

California installation rules combine statute and building-code details, and the code half has moved. Health and Safety Code Section 17926 establishes coverage; the California Residential Code carries the placement rules, and in the 2025 CRC in force since 1 January 2026 they sit at Section R311. They were at R315 through the 2022 edition, and R315 now covers sleeping lofts, so a citation to CRC R315 for a carbon monoxide rule is a citation to the wrong section unless the work is governed by the older edition. Placement itself is unchanged: outside each sleeping area, on each story of the dwelling unit including basements, and inside a bedroom containing a fuel-burning appliance or opening to a bathroom that has one. Devices must be approved and listed by the State Fire Marshal under Section 13263, and combination smoke and CO units are acceptable where they are listed and give distinct alarms for each hazard.

Who handles maintenance of CO devices in California rentals?

California landlord carbon monoxide detector responsibilities start with installation and move-in operability. Under Health and Safety Code Section 17926, the owner must provide compliant devices in covered units. Tenants must notify the owner when an alarm becomes inoperable or deficient, and owners may enter for repair and testing under Civil Code Section 1954 notice rules. This split duty is important during turnover because missed notifications and undocumented repairs can create avoidable disputes. Property managers usually maintain service logs, battery checks, and work-order records to show continuous compliance.

What is the fine for missing a required CO alarm in California?

The California carbon monoxide detector statute sets a capped infraction model. Health and Safety Code Section 17926(c) allows up to a 200 dollar fine per offense, and the owner generally receives a written 30-day notice to cure before monetary penalties are imposed. While the direct fine is limited, the larger risk is operational: unresolved violations can delay inspections, complicate rental habitability disputes, and increase liability exposure after an incident. For that reason, compliance teams treat notice letters as high-priority corrective actions rather than waiting until a follow-up inspection cycle.

How do California rules differ from Texas carbon monoxide laws?

California has a statewide residential framework in Health and Safety Code Section 17926, plus code-level requirements in the California Residential Code at Section R311 under the 2025 edition and at R315 under the 2022 one. Texas does not currently impose a broad statewide home mandate and relies more heavily on local adoption and limited statewide sectors such as child-care operations. If you manage properties in both states, build separate compliance checklists instead of reusing one policy. For a side-by-side legal baseline, review Texas CO detector laws before finalizing procurement and inspection workflows.

Practical CO Detector Guides

Beyond legal requirements, these guides help you choose, install, and maintain CO alarms:

Where to place carbon monoxide detectors, room-by-room placement recommendations
CO detector beeping patterns, what different alarms mean
What to do if your detector goes off, emergency response checklist
CO resources and links, official agencies and safety information