Ralph is spot on with that.
However it wouldn't hurt to have the power company check for gas leaks, in addition to calling in a HVAC company.
Thomas, your landlord has not made your rental unit habitable. A malfunctioning furnace that repeatedly sets off CO alarms is dangerous and potentially lethal. I don't think any court of law would question the need to have that fixed at the landlord's expense. If the landlord won't do it, you have an implicit right to have the repairs done and deduct them from your rent. And maybe if the landlord refuses to cooperate, a judge could sentence them to stay in your apartment in the coldest part of the winter with the gas heat turned on? (Like a judge did to a slumlord in NYC some years back...)
California law regarding these matters is pretty inclusive, but local laws may add further landlord responsibilities.
Also it is illegal for a landlord to retaliate (by eviction, raising rent, harassment, etc) if you exercise your tenant rights.
PS-If the landlord is at all uncooperative, do everything in writing for communications about this issue, document everything, in case it does go to court.
Pertinent to this is California state law, from the Department of Consumer Affairs:
Most landlord-tenant relationships go smoothly. However, problems sometimes do arise. <span style="font-size: 12pt;">
For example, what if the rental unit's furnace goes out in the middle of the winter?</span> What happens if the landlord sells the building or decides to convert it into condominiums? This section discusses these and other possible issues and problems in the landlord-tenant relationship.
REPAIRS AND HABITABILITY
<span style="font-size: 12pt;">
A rental unit must be fit to live in; that is, it must be habitable. In legal terms, "habitable" means that the rental unit is fit for occupation by human beings and that it substantially complies with state and local building and health codes that materially affect tenants' health and safety.129 </span>
California law makes landlords and tenants each responsible for certain kinds of repairs, although landlords ultimately are legally responsible for assuring that their rental units are habitable.
Landlord's responsibility for repairs
Before renting a rental unit to a tenant, a landlord must make the unit fit to live in, or habitable. Additionally, while the unit is being rented, the landlord must repair problems that make the rental unit unfit to live in, or uninhabitable.
The landlord has this duty to repair because of a California Supreme Court case, called Green v. Superior Court,130 which held that all residential leases and rental agreements contain an implied warranty of habitability. <span style="font-size: 12pt;">
Under the "implied warranty of habitability," the landlord is legally responsible for repairing conditions that seriously affect the rental unit's habitability.131 That is, the landlord must repair substantial defects in the rental unit and substantial failures to comply with state and local building and health codes.132</span> However, the landlord is not responsible under the implied warranty of habitability for repairing damages that were caused by the tenant or the tenant's family, guests, or pets.133
Generally, the landlord also must do maintenance work which is necessary to keep the rental unit liveable.134 Whether the landlord or the tenant is responsible for making less serious repairs is usually determined by the rental agreement.
The law is very specific as to what kinds of conditions make a rental uninhabitable. These are discussed below.
Tenant's responsibility for repairs
Tenants are required by law to take reasonable care of their rental units, as well as common areas such as hallways and outside areas. Tenants must act to keep those areas clean and undamaged. Tenants also are responsible for repair of all damage that results from their neglect or abuse, and for repair of damage caused by anyone for whom they are responsible, such as family, guests, or pets.135 Tenants' responsibilities for care and repair of the rental unit are discussed in detail below.
Conditions that make a rental unit legally uninhabitable
<span style="font-size: 12pt;">
There are many kinds of defects that could make a rental unit unlivable. The implied warranty of habitability requires landlords to maintain their rental units in a condition fit for the "occupation of human beings. "136 In addition, the rental unit must "substantially comply" with building and housing code standards that materially affect tenants' health and safety.137 </span>
<span style="font-size: 12pt;">
A rental unit may be considered uninhabitable (unlivable) if it contains a lead hazard that endangers the occupants or the public, or is a substandard building because, for example, a structural hazard, inadequate sanitation, or a nuisance endangers the health, life, safety, property, or welfare of the occupants or the public.138 </span>
A dwelling also may be considered uninhabitable (unlivable) if it substantially lacks any of the following:139
Effective waterproofing and weather protection of roof and exterior walls, including unbroken windows and doors.
Plumbing facilities in good working order, including hot and cold running water, connected to a sewage disposal system.
<span style="font-size: 12pt;">
Gas facilities in good working order. </span>
<span style="font-size: 12pt;">
Heating facilities in good working order. </span>
An electric system, including lighting, wiring, and equipment, in good working order.
Clean and sanitary buildings, grounds, and appurtenances (for example, a garden or a detached garage), free from debris, filth, rubbish, garbage, rodents, and vermin.
Adequate trash receptacles in good repair.
Floors, stairways, and railings in good repair.
In addition to these requirements, each rental unit must have all of the following:
A working toilet, wash basin, and bathtub or shower. The toilet and bathtub or shower must be in a room which is ventilated and allows privacy.
A kitchen with a sink that cannot be made of an absorbent material such as wood.
Natural lighting in every room through windows or skylights. Windows in each room must be able to open at least halfway for ventilation, unless a fan provides mechanical ventilation.
Safe fire or emergency exits leading to a street or hallway. Stairs, hallways, and exits must be kept litter-free. Storage areas, garages, and basements must be kept free of combustible materials.140
Operable dead bolt locks on the main entry doors of rental units, and operable locking or security devices on windows.141
Working smoke detectors in all units of multi-unit buildings, such as duplexes and apartment complexes. Apartment complexes also must have smoke detectors in common stairwells.142
A locking mail box for each unit. The mail box must be consistent with the United States Postal Service standards for apartment housing mail boxes.143
Ground fault circuit interrupters for swimming pools and antisuction protections for wading pools in apartment complexes and other residential settings (but not single family residences).144
The implied warranty of habitability is not violated merely because the rental unit is not in perfect, aesthetically pleasing condition. Nor is the implied warranty of habitability violated if there are minor housing code violations, which, standing alone, do not affect habitability.145
While it is the landlord's responsibility to install and maintain the inside wiring for one telephone jack, it is unclear whether the landlord's failure to do so is a breach of the implied warranty of habitability.146
An authoritative reference book suggests two additional ways in which the implied warranty of habitability may be violated. The first is the presence of mold conditions in the rental unit that affect the livability of the unit or the health and safety of tenants. The second follows from a new law that imposes obligations on a property owner who is notified by a local health officer that the property is contaminated by methamphetamine. (See When You Have Decided to Rent, Methamphetamine Contamination.) This reference book suggests that a tenant who is damaged by this kind of documented contamination may be able to claim a breach of the implied warranty of habitability.147
Limitations on landlord's duty to keep the rental unit habitable
Even if a rental unit is unlivable because of one of the conditions listed above, a landlord may not be legally required to repair the condition if the tenant has not fulfilled the tenant's own responsibilities.
In addition to generally requiring a tenant to take reasonable care of the rental unit and common areas (see above), the law lists specific things that a tenant must do to keep the rental unit liveable.
Tenants must do all of the following
Keep the premises "as clean and sanitary as the condition of the premises permits."
Use and operate gas, electrical, and plumbing fixtures properly. (Examples of improper use include overloading electrical outlets; flushing large, foreign objects down the toilet; and allowing any gas, electrical, or plumbing fixture to become filthy.)
Dispose of trash and garbage in a clean and sanitary manner.
Not destroy, damage, or deface the premises, or allow anyone else to do so.
Not remove any part of the structure, dwelling unit, facilities, equipment, or appurtenances, or allow anyone else to do so.
Use the premises as a place to live, and use the rooms for their intended purposes. For example, the bedroom must be used as a bedroom, and not as a kitchen.148
Notify the landlord when dead bolt locks and window locks or security devices don't operate properly.149
However, a landlord may agree in writing to clean the rental unit and dispose of the trash.150
If a tenant violates these requirements in some minor way, the landlord is still responsible for providing a habitable dwelling, and may be prosecuted for violating housing code standards. If the tenant fails to do one of these required things, and the tenant’s failure has either substantially caused an unlivable condition to occur or has substantially interfered with the landlord’s ability to repair the condition, the landlord does not have to repair the condition.151 However, a tenant cannot withhold rent or has no action against the landlord for violating the implied warranty of habitability if the tenant has failed to meet these requirements.152
Responsibility for other kinds of repairs
As for less serious repairs, the rental agreement or lease may require either the tenant or the landlord to fix a particular item. Items covered by such an agreement might include refrigerators, washing machines, parking places, or swimming pools. These items are usually considered "amenities," and their absence does not make a dwelling unit unfit for living.
These agreements to repair are usually enforceable in accordance with the intent of the parties to the rental agreement or lease.153
Tenant's agreement to make repairs
The landlord and the tenant may agree in the rental agreement or lease that the tenant will perform all repairs and maintenance in exchange for lower rent.154 Such an agreement must be made in good faith: there must be a real reduction in the rent, and the tenant must intend and be able to make all the necessary repairs. When negotiating the agreement, the tenant should consider whether he or she wants to try to negotiate a cap on the amount that he or she can be required to spend making repairs. Regardless of any such agreement, the landlord is responsible for maintaining the property as required by state and local housing codes.155
