What does it mean?
B2112 is a Body (airbags, seat belts, body electronics) fault code. It indicates: 5-Volt Supply Circuit Low .
Symptoms
- Memory SET function does not work, positions cannot be stored
- No confirmation chime or indicator when trying to store a position
- Memory recall moves the seat to the wrong place or not at all
- Several unrelated position sensors read implausible values at the same time when the reference is low
- Mirror and steering column memory functions lost together with the seat
- Fault returns immediately after clearing
Likely causes
- Switch contacts stuck closed by dirt, wear or a spilled drink in the door or seat switch pack
- Door trim or seat trim pressing against the switch after a previous repair or a loose clip
- Switch signal wire shorted to ground in the door boot or under the seat
- 5V reference circuit pulled down by one failed sensor sharing the same reference line
- Too many devices on a shared reference after an accessory installation
- Corroded or water damaged connector at the memory module
- Poor module ground raising the measured reference error
- Internal regulator failure inside the memory or body control module
How to fix it
- Confirm the manufacturer definition and which pin carries the SET switch input
- Watch the switch state in live data with nothing touching the switch, a permanent pressed state confirms a stuck input
- Remove the trim panel and free the switch, then recheck live data
- Unplug the switch pack: if the input clears, the switch is at fault, if it stays active the harness is grounded
- Measure the 5V reference at two or three different sensors, a low reading everywhere points at the module or a shorted branch
- Disconnect sensors one at a time on the shared reference until the voltage recovers, that isolates the shorted device
- Clean or replace the switch and repair the harness
- Clear the code, store and recall each memory position to verify the repair