Oregon Revised Statutes Property Rights and Transactions § 90.317

(1) A landlord shall ensure that a dwelling unit has one or more carbon monoxide alarms installed in compliance with State Fire Marshal rules and the state building code if the dwelling unit:

(2) The landlord shall provide the tenant of the dwelling unit with a written notice containing instructions for testing of the alarms. The landlord shall provide the written notice to the tenant no later than at the time that the tenant first takes possession of the premises.

(3) If the landlord receives written notice from the tenant of a deficiency in a carbon monoxide alarm, other than dead batteries, the landlord shall repair or replace the alarm.

(4) Supplying and maintaining a carbon monoxide alarm required under this section is a habitable condition requirement under ORS 90.320.