What does it mean?
B2227 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Sunroof ECU Internal .
Symptoms
- Air bag warning lamp on and the front restraint system disabled.
- The fault may be intermittent at first, with the lamp coming on over bumps and going out after a restart.
- No deployment of the front air bags while the sensor is unreachable.
- The problem appears right after body repair, bumper removal or driving through standing water.
- Other sensors on the same harness branch also report communication or supply faults.
Likely causes
- Open or high resistance in the sensor communication wire, typically where the front harness runs behind the bumper or along the inner fender.
- Water, salt or corrosion in the sensor connector interrupting the signal path.
- Connector not fully latched or terminal pushed back after front end repair or bumper removal.
- Harness damage from a front impact, rodent chewing or a badly routed loom rubbing on sheet metal.
- Sensor internal failure that stops it answering the module.
- Weak or unstable sensor supply voltage so the sensor resets during operation.
- On some vehicles this code number is assigned instead to an internal sunroof control unit fault.
How to fix it
- Disconnect the battery and observe the specified stand down time before handling any restraint connector.
- Read all restraint codes and note whether the fault is current, and whether it is limited to one side.
- Inspect and unlatch the sensor connector, then check for green corrosion, water, bent pins and a properly seated terminal lock.
- Measure continuity and resistance of the communication and supply wires between the sensor connector and the module connector, both to each other and to ground.
- Perform a wiggle test along the front harness while monitoring the circuit so an intermittent break can be located.
- Repair the harness with proper crimped and sealed joints rather than twisted splices, and reroute it away from sharp edges.
- Replace the front crash sensor only after the wiring and supply have been proven, then clear the codes and verify the lamp self test.