volvo s40 t5 immobilizer try start again

[domhart10]

Hi guys,

I thought I would pop this down here as it was very difficult to find any info on this that was clear or any posts I came across were never completed.

Jumped in the car to take the S40 for a wiz down to the shops. After I had done, I jumped in and went to start the car and there was absolutly nothing, electrical wirring noise which I think was the power steering but absolutly nothing else after that.

I then checked connections to the fusebox and CEM and everything looked fine. I then thought it might be the key so my other half turned up later with the other key which didnt solve the issue either.

RAC then showed up and checked over everything I had mentioned. He then plugged is equiptment in to read whats going on. Main thing he could see was that the car just could speak to the ECU and connect at all.

Just to add, checked the battery and alternator were working as they should and that was fine as well.

So suspected ECU issue.

They took the car to PSL as my spare ECU was still there and that was plugged in today and hey presto! the car turned over fine.

ECU failure will probably be down to water ingress and slowly deterioration of the board. This had been happening for a while since a previous mapper had the car and noticed this so .... its finally now given up.

Anyway thats all sorted, hope this helps anyone.

[Brimfull]

Originally Posted by domhart10

Hi guys,

I thought I would pop this down here as it was very difficult to find any info on this that was clear or any posts I came across were never completed.

Jumped in the car to take the S40 for a wiz down to the shops. After I had done, I jumped in and went to start the car and there was absolutly nothing, electrical wirring noise which I think was the power steering but absolutly nothing else after that.

I then checked connections to the fusebox and CEM and everything looked fine. I then thought it might be the key so my other half turned up later with the other key which didnt solve the issue either.

RAC then showed up and checked over everything I had mentioned. He then plugged is equiptment in to read whats going on. Main thing he could see was that the car just could speak to the ECU and connect at all.

Just to add, checked the battery and alternator were working as they should and that was fine as well.

So suspected ECU issue.

They took the car to PSL as my spare ECU was still there and that was plugged in today and hey presto! the car turned over fine.

ECU failure will probably be down to water ingress and slowly deterioration of the board. This had been happening for a while since a previous mapper had the car and noticed this so .... its finally now given up.

Anyway thats all sorted, hope this helps anyone.

Great to hear that you have found the issue and at least at the moment she's up and running again.

[FunkyMelon]

It could be the ECU but unless there are signs of water ingress (you have had yours apart a few times) then I expect it's something else.

Have a read of this.

https://www.volvoforums.org.uk/showthread.php?t=285582

Volvo have redesigned this part about 4 times in the lifespan of our cars, so it could be this you're seeing.

Not an expensive part but if yours hasn't failed yet, chances are it will at some point.

[domhart10]

Originally Posted by FunkyMelon

It could be the ECU but unless there are signs of water ingress (you have had yours apart a few times) then I expect it's something else.

Have a read of this.

https://www.volvoforums.org.uk/showthread.php?t=285582

Volvo have redesigned this part about 4 times in the lifespan of our cars, so it could be this you're seeing.

Not an expensive part but if yours hasn't failed yet, chances are it will at some point.

Water ingress can happen on any P1, it is a known issue as a lot of older T5's have never had their ECU split open but they arent positioned in the best location.

This was my finding from an issue I had as there was nothing else online pointing to this on google, where there was already for your issue (Which is why you are fwding the post). So just trying to get this also raised on the search engine to help others.

"If yours hasn't failed yet, chances are it will at some point", this is like saying if my brakes havent worn out, they will soon lol I can list you out all the parts that will most likely fail with general use.


So to sum up the post, yes 100% ECU issue. As soon as the new ECU was put on the car was fine right away, luckily the garage had a backup so could clone everything over to the new ECU.

[FunkyMelon]

Originally Posted by domhart10

Water ingress can happen on any P1, it is a known issue as a lot of older T5's have never had their ECU split open but they arent positioned in the best location.

This was my finding from an issue I had as there was nothing else online pointing to this on google, where there was already for your issue (Which is why you are fwding the post). So just trying to get this also raised on the search engine to help others.

Fair enough, I wasn't disagreeing with you, I've read it's common to get water ingress overtime on these, increasingly more so with yours since it's been opened before.

Originally Posted by domhart10

"If yours hasn't failed yet, chances are it will at some point", this is like saying if my brakes havent worn out, they will soon lol I can list you out all the parts that will most likely fail with general use.

Slightly different, all brakes wear out on any car, they are consumables. ignition switches usually aren't, they're just another item on the rather long list of 'when not if' failure points on our cars

Originally Posted by domhart10

So to sum up the post, yes 100% ECU issue. As soon as the new ECU was put on the car was fine right away, luckily the garage had a backup so could clone everything over to the new ECU.

Glad you got it sorted Having not moved my ECU before, what is it that fails that allows water in?