What does it mean?
B2122 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Ignition Run Control 1 Circuit Low .
Symptoms
- Airbag warning lamp on continuously
- Side airbag and curtain protection on the driver side disabled
- Additional satellite sensor or communication codes stored with it
- Fault returns straight after clearing, or appears only over bumps
- Seat belt pretensioner functions may also be flagged
- No other driveability effect, but the restraint system cannot be trusted until it is fixed
Likely causes
- Harness chafed where it runs down the B pillar or under the sill trim
- Water in the sill or footwell corroding the satellite sensor connector
- Sensor internally failed and loading the communication line low
- Wiring damaged during audio, alarm or trim installation, a very common cause on this circuit
- Sensor mounting bolt loose or the sensor not properly earthed to the body
- Collision damage or a previous repair that left a poor splice in the loop
- Connector terminals spread or backed out after the plug was disturbed
- Restraint control module internal fault, only after the wiring and sensor are proven
How to fix it
- Disconnect the battery and wait for the specified discharge time before disturbing any connector
- Confirm the manufacturer definition and the satellite sensor location for this application
- Remove the sill trim and inspect the loom for pinch marks, staples, screws and aftermarket taps
- Check the connector and the sensor mounting point for water and corrosion
- With the sensor unplugged, measure the communication line to ground, it must read open
- If the line is grounded with the sensor off, repair the harness, if it is only grounded with the sensor connected, replace the sensor
- Verify the sensor is torqued to a clean body surface, these sensors rely on solid mounting
- Reconnect, clear the code and confirm the airbag lamp completes a normal self test and stays out on a road test