Motronic

To access the fault system, place an LED test light* between the red wire on the black connector and the yellow/black wire on the blue connector under the shift boot. Then turn the ignition on (but don't start the car) and place a jumper between the brown wire on the black connector and the yellow wire on the white connector for at least 5 seconds. Remove the jumper, and the LED should flash one long pulse, then several shorter pulses (with spaces) indicating codes. Please click here for an example.

The example picture above would indicate a 1234 code. Connect the jumper again for at least 4 seconds to advance to the next code. When "0000" (2.5s flashes at 2.5s intervals) or "4444" is read, the sequence is completed. To clear the codes, connect the jumper with the ignition off, then turn it on. After 5 seconds, remove the jumper, and "4444" should be read.

*Note: California cars come equipped with a "CHECK" light on the dashboard. This light is used in place of the LED, which is not required on these models. Just use the jumper.
Code Description Action
1111 Control unit Defective control unit (common misdiagnosis)
1231 Speed sender Faulty speed sender, bad speedometer cable, or bad cluster fuse
2112 Ignition reference sensor Defective sensor or wiring
2113 Hall sender Defective sensor or wiring
2121 Idle switch Defective or misadjusted sensor, or faulty wiring
2123 Full-throttle switch Defective or misadjusted sensor, or faulty wiring
2141 Knock sensor I Engine knock due to incorrect fuel, incorrect timing, or faulty sensor
2142 Knock sensor I Faulty sensor wiring, faulty sensor, or faulty control unit
2144 Knock sensor II Faulty sensor wiring, faulty sensor, or faulty control unit
2231 Idle speed stabilizer has exceeded adaptive range Throttle valve adjustment incorrect, incorrect timing, evap system faulty, or intake air leaks
2232 Air flow sensor potentiometer Defective sensor or wiring
2312 Coolant temperature sensor Defective sensor or wiring
2341 Oxygen sensor control exceeded Idle mixture incorrectly adjusted, faulty sensor wiring, leaking cold start valve, evap system faulty, or intake air leaks
2342 Oxygen sensor system (faulty signal or exceeding adjustment range) Faulty sensor wiring, faulty sensor, incorrect idle speed, leaking cold start valve, or intake air leaks
2411 EGR system (California only) Intake air temperature sensor faulty, faulty EGR sensor wiring, faulty or plugged EGR system
4431 Idle stabilizer valve Faulty wiring or valve, or control unit
4444 No faults -