Long story short my car broke down a couple months ago and the garage replaced the ECU as they determined that was the issue. It also transpired there was a wiring fault which caused a short and then more recently I found out they replaced one of the 3 ignition coils (but not the other 2)

A few days ago my engine management fault light came on and the car started shuddering, nursed it home and got it to another garage (an independent) today. When I spoke to this second garage he felt the story didn’t add up so when took it round today he checked the ECU chassis number and the car chassis number in front of me. They matched. The replacement ECU I sourced and was second hand so the guy today was saying should have a different chassis number? Is that the case? Made sense to me and I’m mightily pissed off that the first garage (a main dealer) might have shafted me on this. Left a message with their workshop outlining the number mismatch and to call me back.

So pitchforks or reasonable explanation? Ta

ECU you say?

molgrips to the thread!

Wouldn’t a main dealer program the ecu to match the chassis if that is a possible variable. Not that I trust most main dealers, I would much rather have a reliable independent garage that I had built up a relationship with over the years. But if they are doing the job right, which some will do, then I would expect them to do that.

Yeah i did wonder about reassigning or changing the number but have no idea tbh. I’d far rather an independent but as it was a breakdown and coincidentally near this garage (where I bought the car second hand) plus it has a good reputation locally* then thought it would be all good. The conversation I had with them last week about, ‘finding the wiring fault quite late on,’ did worry me though.

Pitchfork pending…

depending on the make an model, but you need to ‘divorce’ the old ECU from the car its attached to ( you can’t just unplug and pass it on otherwise it can never be attached to another car) and the new (or new to you) ECU also needs to be matched to the car otherwise it won’t talk to the immobiliser, central locking etc. So although you may have acquired the ECU yourself its not just plug an play – the garage would have had to transfer the identity of the old ECU to the new one.

So the swapped ECU should have an identity that matches your car – digitally speaking. If a serial number is physically stamped on the case of the ECU thats a different issue

If you were doing this DIY you’d need to post your old ECU away and have the ID transferred to the new/refurb one otherwise the car wouldn’t recognise it. If you don’t do that you have to buy the ECU, ignition barrel and door locks from a donor car and swap them all in a oner.

So on the diagnostic tool the ECU number should match the VIN on the chassis even if from a different vehicle?

What car is it badger?

Skoda fabia 1.2 hci ambiente*

*aka the batmobile

So on the diagnostic tool the ECU number should match the VIN on the chassis even if from a different vehicle?

perhaps ‘could’ rather than ‘should’ – the car and the ECU certainly need to believe they belong together

the car and the ECU certainly need to believe they belong together

I like this 🙂

Yeah, the dealership would have flashed the old ecu with your cars details. I don’t see anything wrong with that.

Pitchfork stood down

Garage called and the service manager agrees that the numbers should *not* match and sounds like the original ECU is in place. He’s going to do some digging and get back to me. To be continued…

Really?…interesting

If you install an “new” ecu (i.e. one that was not originally coded to the car) and you fail to update the volatile memory in that ecu with the cars End-of-line data (VIN, tyre sizes, options etc) then you would normally expect to get the MIL illuminated on the dash board to tell you there is an problem! As such, i would expect ALL garages (and especially main dealers) to code any new control unit appropriately!