OBD2 Car ScannerWhat does B1812 mean?
B1812 stands for Lamp Backup Switch Input Circuit Short To Battery. 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 B1812 mean?
B1812 means “Lamp Backup Switch Input Circuit Short To Battery”. 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 B1812?
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 B1812?
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
- B1808Lamp Tail Output Circuit Short To Battery
- B1809Lamp Tail Output Circuit Short To Ground
- B1810Lamp Backup Switch Input Circuit Failure
- B1811Lamp Backup Switch Input Circuit Open
- B1813Lamp Backup Switch Input Circuit Short To Ground
- B1814Wiper Rear Motor Down Relay Coil Circuit Failure
- B1815Wiper Rear Motor Down Relay Coil Circuit Open
- B1816Wiper Rear Motor Down Relay Coil Circuit Short To Battery
Code meanings can vary by manufacturer. This page is general guidance, not a repair manual. Always confirm the cause before replacing parts.