Hello I just joined here I recently bought an 05 SL and I love it. I have an issue with mine right now but maybe someone here already knows.

My car died on me and I took it to 2 different shops and had it diagnosed by both as a failed ECM/ECU and it would need to be repaired or replaced.

I bought one and dont know if it is the correct one. I know about the part numbers needing to match but HOW MUCH of it has to match ? All of it or just part of it. The two I have are

OLD/ORIGINAL: MW A56-X51 ZZ5 4725
NEW: MU A56-X50 ZZ4 4725

do they match ? Not sure which part of the number to use ?

 

These are probably serial numbers. Part numbers are usually manufacturer-based.

 

But I need to know which part of the numbers must match ?

I bought one off ebay that had all matching numbers except the last four....