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Getting the fault codes to appear on the "Check Engine" light.

Much of this info came from Jim Conforti at Gateway Tech, 1995 and 1996.

For related information, see:

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.

More detail on these early systems can be found in the Bentley manuals.

Late 1980's 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 doesn't 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.
Malfunctioning System. Fault Code Comments.
DME Control Unit 1211
Air Mass/Volume Sensor 1215
Throttle Potentiometer 1216
Output Stage, Group 1 1218
Output Stage, Group 2 1219
EGO(O2) Sensor 1 1221
EGO(O2) Sensor 2 1212
Lambda Control 1 1222
Lambda Control 2 1213
Coolant Temp. Sensor 1223
Intake Air Temp. Sensor 1224
Knock Sensor 1 1225
Knock Sensor 2 1226
Knock Sensor 3 1227
Knock Sensor 4 1228
Battery Voltage/DME Main Relay 1231
Throttle Idle Switch 1232
Throttle WOT Switch 1233
Speedometer A Signal 1234
A/C Compressor cut off 1237
A/C Compressor 1242
Crankshaft Pulse Sensor 1243
Camshaft Sensor 1244
Intervention AEGS 1245
Ignition Secondary Monitor 1247
Fuel Injector 1 (or group 1) 1251
Fuel Injector 2 (or group 2) 1252
Fuel Injector 3 1253
Fuel Injector 4 1254
Fuel Injector 5 1255
Fuel Injector 6 1256
Fuel Injector 7 1257
Fuel Injector 8 1258
Fuel Pump Relay Control 1261
Idle Speed Actuator 1262
Purge Valve 1263
EGO Heater 1264
Fault Lamp (check engine) 1265
VANOS 1266
Air Pump Relay Control 1267
Ignition Coil 1 1271
Ignition Coil 2 1272
Ignition Coil 3 1273
Ignition Coil 4 1274
Ignition Coil 5 1275
Ignition Coil 6 1276
Ignition Coil 7 1277
Ignition Coil 8 1278
Control Unit Memory Supply 1281
Fault Code Memory 1282
Fuel Injector Output Stage 1283
Knock Control test Pulse 1286
No Failures 1444
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.
Model Year. Body Style. Model. Processor type. EPROM type.
9/84 - 9/87 E30 325e/es 1802 2732A
88 E30 325 8052 27256
87-88 E30 325i/is/iX 8052 27256
89-91 E30 325i/is/iX 80515 27256
89-91 E30 M3 8051 27128/256
>8/91 E36 325i/is MCS-96/51 27C256
>9/92 E36 325i/is/ic MCS-96/51 27C512
93+ E36 M3-Euro MCS-96/51 27C256
95+ E36 M3 MCS-96/51 27C512