What does it mean?
B2190 is a Body (airbags, seat belts, body electronics) fault code. It indicates: DTC Detection Logic (Anti-Theft Antenna Amp) . This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms
- Rear passenger window moves on its own or will not respond to the master switch
- Engine cranks but will not start, with the security indicator flashing
- Key is not recognised, or only recognised sometimes
- Immobiliser or key message in the driver display
- Module stays awake and drains the battery on the window variant
- Vehicle starts and immediately stalls after a couple of seconds
Likely causes
- Liquid spilled into the driver master switch bridging the window input to a supply pin
- Wiring chafed in the door boot and touching a permanently live conductor
- Terminal pushed back in the switch connector, contacting an adjacent battery feed
- Immobiliser antenna ring connector at the ignition lock loose or corroded
- Antenna coil wiring broken where it flexes with the steering column
- Antenna amplifier failed internally so the transponder can no longer be read
- Aftermarket remote start or alarm interfering with the immobiliser antenna circuit
- Body or immobiliser module fault, only after the wiring is proven
How to fix it
- Confirm the manufacturer definition and the pin assignments for this vehicle
- For the window variant, disconnect the master switch and measure the up input for voltage, key on
- Voltage present with the switch unplugged means a harness short, no voltage points at the switch itself
- Inspect the door boot loom for chafing and green corrosion
- For the immobiliser variant, try a spare key first, and remove other transponders and metal from the key ring
- Unplug and inspect the antenna ring connector at the ignition lock, and check the coil wiring for breaks
- Test the battery voltage, a weak battery can stop the transponder being read reliably
- Repair the wiring or replace the antenna amplifier or switch, then verify the key is recognised on every start and the window follows its switch