M140i B58 Faulty ECU

Issue

This BMW F20 M140i with a B58 engine was experiencing misfires on one cylinder. Sometimes the spark plug wouldn’t receive a signal, especially when the engine was warm. The owner, a mechanic himself, checked everything and replaced various parts. His final conclusion was: the spark plugs, coils, and wiring were good. He was left with one conclusion: the engine management system was faulty. This car uses an MG1CS003 ECU. He contacted us and asked if we could help him with it. Of course! We gave him the choice between a new ECU and a used one. This saved him over a thousand euros, so it was understandable that he opted for a used ECU. The plan was to clone the ECU directly to a used one.

Working method

The cloning process wasn’t successful due to newer security measures in this model. Fortunately, we don’t give up easily, and the problem was solved in another way. We programmed the ECU we used from scratch. We wrote the immobilizer’s ISN, set the correct chassis number (VIN), loaded the correct software, and adapted the coding to this M140i. We then checked the adaptations and performed a few more tests.

Result

The BMW M140i is running smoothly on all cylinders again. No more misfires when the engine is warm. The car starts immediately and accelerates smoothly. There are no more error codes in the system. The customer didn’t have to buy a new ECU and saved thousands of euros. This case study demonstrates that programming an MG1CS003 ECU from scratch is a smart solution if cloning isn’t possible with a BMW B58.