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Bosch Motronic Failures
(88pin ECUs)

There are many failures of Bosch Motronic DIS (Direct or Distributorless Ignition System) ECUs commonly fitted to Alfa Romeo, BMW and 4 cylinder Peugeot cars from about 1992 onwards. Click here to see photo of this ECU.

Part numbers are 0261 20X 4XX/5XX/others. The system fitted to 4 cylinder Alfa Romeo and 6 cylinder BMW cars is 'coil per cylinder' system whilst that fitted to 4 cylinder Peugeot is a twin coil 'wasted spark' system. Click here to see photo of the 88 pin Bosch Motronic for accurate identification. (It is important not to confuse this system with earlier Peugeot and Citroen cars which use 35 and 55 pin Motronic ECUs click here for details of this system.)

Symptoms

1) Misfire on one (or more) cylinders (Alfa and BMW), or no spark on 2 cylinders for systems fitted to 4 cylinder Peugeot.

Diagnostic Checklist

1) ECU failures so far have been associated with coil pack failure which can be confirmed by VERY close visual inspection of coil pack - look for split in coil casing or burn marks. All the evidence we have seen indicates that coil pack failure guarantees ECU failure.
2) If possible, check for severly reduced coil KV on effected cylinders. A very weak pulse can sometimes be detected.
3) Do not confuse this system with earlier 35 and 55 pin Motronic systems fitted to some Peugeot and Citroen cars. These earlier systems had separate ignition amplifiers mounted in the engine compartment. Refer to ECU photographs HERE to get ECU identification right.

DO NOT FIT REPAIRED OR NEW ECU UNTIL NEW COIL(S) IS FITTED

If in doubt about whether ECU is cause of problem on your car, try our low-cost ECU inspection service. This is fast, cheap and many Motronic ECUs with this common problem can be fixed during inspection - avoiding costs of rebuild.

We offer a low-cost rebuild service for these ECUs. Please click here for our address and ECU repair quote request form.

DO NOT REMOVE ECU COVER - THESE ECUs FEATURE HIGHLY SENSITIVE MICROELECTRONIC INTEGRATED CIRCUITS THAT CAN BE DAMAGED BY NORMAL ENVIRONMENTAL ELECTROSTATIC CHARGES.

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