New on here.. need help with engine ECU


Registered User
Sep 23, 2011
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I have a 2004 Audi A3 1.6.. Engine ECU (part no. 03C906056AP/0261S02057) is staying live after ignition off so is draining the battery.

I sent the unit to ECU testing who after a week said they could find no fault.
I then called ECU Repairs who said that particular part cant be fixed or data transferred.
I found a refurb part at Euro parts who reckon they can transfer the data from mine on to a replacent part for around £440 all in.
Or, Audi can re code a replacement part if I manage to pick one up cheap and take a punt on it being ok.

So, much conflicting info.. can anyone advise whats best to do?
Get replacement module, take it to audi to code it up, as they will need to do immo & attach vin no. to it aswell.
Scotty, there is something fishy here. If indeed the ECU is staying on and draining ther battery, it would have been diagnosed by ECU testing quite easily by placing a meter in the power-in line. It could also be tested in-car for the same current drain by any competent electrician. Are you quite sure it is the ECU that is draining the battery? There are many other potential curent drains in the car which could be at fault. Suggest you may like to get an electrican to give it the once-over and confirm where this current is actually going. Good luck.
Yeah tbh never heard of an ecu hanging power, then again anythings possible these days, common fault for this are oem radio's, they are synonymous for this.
The rns 510 is also an issue for golfs etc until a gateway is updated to newest, whats crap is you have to pay for it when vag should replace anyway.
Had an ex audi guy tell me it's definitely the ECU draining it.
Unit is still hot long after ignition off. Had the unit out for a week and there wasn't any drain.
Might try and get a spare and take it to audi
Cheers guys
Arghh just spoke to Audi and said ECU is not causing the drain, it's probably relay somewhere??
Don't know what to do next, although it's good if I don't have to fork out for a replacement unit..
Scotty, what I would do now is the following. With the ignition off, I would go to the engine fusebox and carefully remove each fuse, and place a DC current meter probes across the internal fuse contacts. You need a current meter that can switch down to 1 or two amps. Then do the same thing with the passenger fusebox. Record any current drain, then look to see what electrical equipment is fed by that same fuse. You can do this test for free. It might just point you in the right direction. Good luck.