OBD2 Car ScannerWhat does B2104 mean?
B2104 stands for Door Passenger Key Cylinder Switch Failure. A body control module has found a fault in a comfort or safety system such as airbags, lights, doors, seats or climate control.
Body codes cover the airbags, seats, lights, doors and comfort systems. When the car's computer sees a reading outside its normal range, it stores this code and may turn on a warning light on the dashboard.
Common causes
- Damaged wiring or a loose connector (often under seats)
- Faulty switch, sensor or motor
- Low battery voltage
- Faulty body control module
What to do
- Read all stored and pending codes with a scanner. Several codes together often point to one cause.
- Note the freeze frame data (speed, temperature, load) recorded when the code was set.
- Inspect the wiring and connectors of the part named in the code for damage, corrosion or looseness.
- Fix the most likely and cheapest cause first, then clear the code and drive to see if it comes back.
Read this code from your own car
Plug in a cheap ELM327 adapter and the app shows every fault code, what it means and how to fix it.
Frequently asked questions
What does B2104 mean?
B2104 means “Door Passenger Key Cylinder Switch Failure”. It belongs to the body system group: A body control module has found a fault in a comfort or safety system such as airbags, lights, doors, seats or climate control.
Is it safe to drive with B2104?
You can usually drive carefully for a short time, but fix it soon to avoid further damage or higher fuel use.
How do I clear B2104?
Fix the cause, then clear the code with an OBD2 scanner or app. If the fault is still there, the code will come back.
Related codes
- B2100Door Driver Key Cylinder Switch Failure
- B2101Head Rest Switch Circuit Failure
- B2102Antenna Circuit Short to Ground
- B2103Antenna Not Connected
- B2105Throttle Position Input Out of Range Low
- B2106Throttle Position Input Out of Range High
- B2107Front Wiper Motor Relay Circuit Short to Vbatt
- B2108Trunk Key Cylinder Switch Failure
Code meanings can vary by manufacturer. This page is general guidance, not a repair manual. Always confirm the cause before replacing parts.