CO Alarms for Tenants in Germany 2025

Safety & Emergency Protections 3 min read · published September 07, 2025

As a tenant in Germany, you should know how CO alarms save lives and who is responsible for installation and maintenance. This guide explains in clear language which legal duties and practical recommendations apply in 2025, how to report unexplained CO alarms or visible signs of combustion residues, and what rights you have in case of danger. We describe concrete steps to contact your landlord, which evidence is useful, and when a report to authorities makes sense. The goal is to give you confidence so you can live safely and react quickly in an emergency without being overwhelmed by legal terms. If needed, you will also find guidance on authorities, important links and a step-by-step plan.

Why CO alarms matter

Carbon monoxide (CO) is odorless and can occur with leaking heating systems, gas boilers or wood stoves. For tenants, a CO alarm is a life-saving early-warning system that protects against poisoning. Although smoke alarm obligations are clearly regulated in many federal states, CO alarms often depend on the type of heating or combustion appliances and on state-level rules. In any case, the basic duties to maintain the rental property are set out in the German Civil Code (BGB).[1]

CO is odorless and can be harmful to health even at low concentrations.

Who is responsible: landlord or tenant?

The landlord must hand over and maintain the rental property in a contract-compliant condition. This implies a duty to eliminate or prevent hazards. Whether the landlord must install a CO alarm depends on the specific situation (e.g. existing gas boiler, central heating system, regional regulations). If in doubt, submit a written defect notice to the landlord.[1]

Always send defect reports in writing and keep a copy.

Practical meaning for tenants

If a CO alarm sounds or you notice symptoms (headache, nausea, dizziness), immediate action is required: ventilate the apartment, check gas supply if accessible, open windows and doors, and inform the landlord and, in emergencies, rescue services.

If you experience acute symptoms, call the emergency number immediately.

How to report defects securely and legally

For a legally secure defect report, use a short clear letter or email to the landlord with date, problem description, photos and a deadline for correction. Mention possible hazards and request confirmation of receipt.

Documentation with date, time and photos strengthens your position with the landlord.
  • Briefly describe the alarm and attach photos or timestamps.
  • Request a response within a clear deadline (e.g. 7 days).
  • Keep all messages and receipts.

What to do if the landlord does not respond

If the landlord does not respond, send a formal defect notice by registered mail or email with delivery confirmation. If still no remedy, rent reduction or remedial measures may be possible; document everything and seek legal advice if needed. Courts of first instance are the local Amtsgerichte; higher instances are the Landgerichte and the Federal Court of Justice (BGH).[2]

Local courts hear most tenancy disputes in the first instance.

How to install a CO alarm safely

Exact placement recommendations depend on the alarm type and manufacturer instructions. Generally: do not mount directly next to heating appliances, place on a wall or ceiling where air circulates, and avoid cooking or steam sources.

Maintenance and testing

Test devices regularly per manufacturer instructions, replace batteries on schedule, and document tests. For hardwired systems, maintenance should be carried out by qualified personnel.

FAQ

Who must install a CO alarm?
It depends on the type of heating system, building class and state regulations; in principle, the landlord is responsible for safe living conditions.[1]
Can I reduce the rent if there is no CO alarm?
Under certain conditions and if there is a hazard, a rent reduction may be possible; carefully assess and document the defect.
Who do I contact in case of acute CO suspicion?
Call emergency services for acute symptoms; also inform the landlord and document the incident.

How-To

  1. Ventilate immediately and leave the apartment if you have symptoms.
  2. Call emergency services and inform the landlord in writing.
  3. Document alarm time, photos and symptoms and request confirmation of the report.
  4. If the landlord does not react, send a formal defect notice by registered mail.

Help and Support / Resources

  1. [1] BGB § 535–580a (Mietrecht) - gesetze-im-internet.de
  2. [2] ZPO - Zivilprozessordnung - gesetze-im-internet.de
  3. [3] Bundesgerichtshof - bundesgerichtshof.de

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Bob Jones
Bob Jones

Editor & Researcher, Tenant Rights Germany

Bob writes and reviews tenant law content for various regions. They’re passionate about housing justice and simplifying legal protections for tenants everywhere.

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