Getting the fault codes to appear on the «Check Engine» light.
Early systems.

Early systems (Motronic 1.1 only, I think) flash the fault codes automatically. If the check engine light comes on, leave the key in the On position, but dont start the car. The check engine light will begin to flash the code after about 3 seconds. Each flash is separated by about 1 second. There arent many codes on this system

1 flash……Air flow sensor malfunction.
2 flashes….Oxygen sensor malfunction.
3 flashes….Coolant Temp. malfunction.
4 flashes….Throttle switch malfunction.

Late 1980s systems. Motronic 1.3

The fault codes for these systems will appear on the check engine light when you turn the ignition key to the On position (but dont start it), then: fully depress the accelerator pedal, then fully release it. Repeat the depress,release cycle 5 times fairly quickly, but not too fast. It should be completed in a few seconds. What you are doing here is clicking the wide open throttle switch then the idle switch each 5 times. This signals the Motronic unit to send the fault codes by flashing the Check Engine light. You should see the light flash once then it will start flashing the 4 digit codes. If there are no faults, you should see the 1444 code (and 2444 if you have a 12 cylinder). The codes appear as a series of flashes for each digit. The flashes indicating one digit are about 1 second apart, the next digit appears after a couple second interval. The rest of the fault codes appear in Table 1 below.

The later systems up to 1995 (Motronic 3.x)

The fault codes appear in the same way as for the Motronic 1.x systems listed above, but it is much trickier to get them to appear. The timing with which you turn the key then depress and release the accelerator pedal is much more critical. You have to depress and release the pedal 5 times, rhythmically, but much faster than for the earlier system. It usually takes a few tries to get it right.

The very latest systems (1995 on)

Fault codes are not available through the check engine light.

The following table requires a HTML 3.0 browser! Upgrade your browser if it appears garbled or doesnt look like a table.

This table lists all the fault codes we could find. If anyone has others, please send them to us. The faults listed are for all different models and some of them are not applicable like Fuel Injector 8 on a 6 cylinder car.

Table 1. The Motronic Fault Codes

For 12 cylinder models, there are additional codes for the second Motronic unit. These codes are the same as above, but the first digit (1) is replaced by 2

Table 2. Motronic Processors and EPROMs

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