What does it mean?
B2101 is a Body (airbags, seat belts, body electronics) fault code. It indicates: IG SW start POS. circuit low .
Symptoms
- Starter keeps cranking or engages by itself
- Vehicle cranks but the key does not need to be held, or will not crank at all
- Starter re engages while the engine is already running, with a harsh grinding noise
- Warning message about the ignition switch or key, or an immobiliser indicator
- Accessory and run circuits behaving inconsistently when the key is turned
Likely causes
- Worn or burnt contacts inside the ignition switch electrical section, sticking in the start position
- Start signal wire shorted to ground in the column harness
- Water or drink spillage running down the column into the switch
- Key cylinder or switch actuator out of adjustment so the switch never fully returns
- Aftermarket remote starter or alarm wired into the start circuit and pulling it low
- Corroded connector at the base of the steering column
- Failed input stage inside the control module
How to fix it
- Watch the ignition switch start input in live data through every key position and confirm it stays low when it should be off
- Disconnect the ignition switch connector and recheck the input, if it goes back to normal the switch is the fault
- Measure the switch contacts with an ohmmeter through each position, checking that the start contact opens cleanly when the key returns
- With the module and the switch disconnected, check the start signal wire for continuity to ground
- Inspect the column connectors for corrosion, water tracks and pushed back terminals
- Remove any remote start or alarm connections from the ignition circuit and retest
- Replace the ignition switch electrical section or repair the wiring, then clear the code and verify normal cranking through several start cycles