Fault Code 1221

Fault code 1221

Airbag sensor (front driver's side)

Conditions for diagnosis
- Ignition on
- Internal function test on airbag trigger unit

Possible cause of fault
- Implausible signal (incorrect airbag sensor installed)
- Open circuit (with respect to wiring between airbag trigger unit and airbag sensor or airbag sensor itself)
- Electrical fault in electric circuit (with respect to wiring between airbag trigger unit and airbag sensor; probably short circuit to positive or short circuit to ground in wiring)
- Faulty (airbag sensor faulty)
- Airbag trigger unit faulty

NOTE: The contact plugs on the wiring harness are identical for the six sensors which are installed. Only the retainers for mounting are different. The airbag sensors under the driver's seat and passenger seat have a threaded retainer but all the other sensors have only a non threaded bush. It is therefore possible to confuse the sensors on the rear wheel arches with the sensors on the lock support. If these are mixed up accidentally, the Porsche System Tester II No 9588 will display this fault code along with the fault type 'implausible signal' It is therefore always important to ensure that the correct sensors are installed at the correct position. The main reason for this is that different levels of sensitivity are set for the different sensors.

Affected pins
- Airbag trigger unit: Pin 73
- Airbag sensor (front driver's side): Pin 2

Diagnosis/troubleshooting