ECU failure/ coolant leak - 2014 GTI, DSG, PP - 61k mileage

[CanaryRossi46]

Hi All,

This is my first post on here so I'm hoping that someone may have had the same happen to them as I am really annoyed??

I'll try and keep it as short as possible but it started when I was crawling along in traffic last month and hadn't travelled very far so I knew engine wasn't that hot, but fan kicked in at full speed and temp gauge started dancing around up at the higher end of scale  (norm sits at 90dg) ....but drove it home a bit concerned. Then the engine light came on so thought I would get this checked out not wanting to drive very far at all.
Turns out that I have coolant problems: the following code were reported - P00B700 (engine coolant flow low/performance), P255600 (engine coolant level sensor/switch), P268100 (engine coolant bypass valve control), P011600 (engine temperature sensor 1)......in the form of a LEAK. I was advised of around £1000 worth of repairs, ie new water pump/thermostat housing, but at this point, nothing about ECU problems. But I wanted a second opinion as they replaced what I thought was the ENGINE Coolant temp sensor (but turns out to be the RADIATOR coolant temp sensor - see below) as when I drove away from the garage the gauge wasn't reading 90dg as normal and the fan was still kicking in like before. I went straight back and told them but I was told 'well that's part of the diagnosis process' which I wasn't that impressed with as I would've thought if you have replaced an item with a new part surely that should work?? Charged £65 +vat for this fitted part.

Other fault codes: B10E7F0 (cruise control front distance range sensor - separated, B116229 (Selector lever park position lock switch - Implausible signal.

I've since taken car to a VAG specialist to investigate a few days ago - they pulled it into workshop to warm the engine up/run it for a bit to also check heating flow as I also had trouble with having to crank the heater speed right up for anything to come out of it along with not very much heat coming from the vents from which I knew was a warm engine. They contacted me to inform me that after the car had been running for a bit, it started surging/revving and then it cut out displaying all sorts of warning lights on dash, ABS, tyre pressure, etc etc.....then they couldn't start the engine at all so they said they would disconnect battery overnite as sometimes they can 'reset' themselves and try again next day which they did and although they could start it, it wouldn't go anywhere. It was at this point that, although they have some diagnostic equipment, they told me that this looks like an ECU problem and it would need further investigation from a specialist before going any further at this stage. They also tell me that the RADIATOR coolant temp sensor has been replaced as they can still see the shiny appearance it has ..... I think the other garage replaced the WRONG temp sensor as fault P011600 reports ENGINE coolant temp sensor on their own diagnostic report so I think I've already shelled out for a part that was ok and the offending part untouched !!!
I actually know an auto-electrician so I asked him to go and have a look at the car for me which he has done and turns out he thinks it is an ECU failure and is making enquiries into my options, ie repair as opposed to replacement as I don't think they are cheap!!
**From what I have read on various threads, I'm thinking that even though the first garage didn't report anything about ECU problems/issues, is it possible that the coolant leak could have caused the ECU failure ......if indeed the ECU is faulty? Secondly, a few months back the 'ACC Front assist not available' warning started coming up to which I read that people said they had cleared dirt/leaf off the front sensor and this sorted it, but also others said they didn't sort and the issue come and goes but they just put up with it......I cleaned my sensor etc but I always keep my car clean so thought unlikely and hey-ho the warning still kept cropping up but more and more regular up to this point. More recently, the 'Stop/start' function not available started to appear too as well as the ACC. I am wondering whether these issues are now connected to the ECU problem AND whether when the ACC fault began a few months back, this was the beginning of the problem? But do ECU's just fail without any warning signs? Or are these two faults unrelated to the ECU?

I would be grateful for any input on this as I've never encountered this before on my mk2 or mk4 and starting to really dislike the way new cars are being made now with practically everything being powered by electrics 🙁. Especially when you get a fault report with codes which should tell you which parts need replacing/repairing but oh no its not as simple as that.....

Thanks in advance

[Carbon VW]

Hello ! I notice the car is 2014. Have you had the battery checked? Is the battery the original or has it been replaced. I had similar problem with overheating etc with similar codes which was rectified with new thermostat housing/WP. Why do you think the coolant leak affected the ECU possibly ? The ECU is by the fuse box in the passenger side and should be fairly clear from the coolant lines. Is there remnants of coolant (staining) on the ECU housing? Powdery white/pink staining

[CanaryRossi46]

Hi Carbon vw thanks for your comments/reply

I acquired car in March 2017 and I havent changed battery so believe its still original....both garages said its in good enough condition. I have heard some say battery can cause issues if not good as so many things depend on it nowadays but mine is ok.

Regarding the coolant leak causing ECU failure, I haven't checked myself if there is any staining on ecu but maybe I should its just that ive also read articles about people damaging it by dropping a spanner on it accidentally aswell as coolant leaking onto wiring so I wondered if this has happened in my case or if it is a separate issue?

If you had your water pump and thermostat housing replaced which sorted your overheating problem, may I ask you how much you were stung for that work please and was it recent? Also, were those 2 parts combined together as when I put my registration no into a local parts supplier, you could buy them as one unit but im sure the garage said for my engine it would be separate items? Is/was yours exactly the same engine as mine, ie 2L, TSI, DSG, PPack?

[Carbon VW]

Hi Carbon vw thanks for your comments/reply

I acquired car in March 2017 and I havent changed battery so believe its still original....both garages said its in good enough condition. I have heard some say battery can cause issues if not good as so many things depend on it nowadays but mine is ok.

Regarding the coolant leak causing ECU failure, I haven't checked myself if there is any staining on ecu but maybe I should its just that ive also read articles about people damaging it by dropping a spanner on it accidentally aswell as coolant leaking onto wiring so I wondered if this has happened in my case or if it is a separate issue?

If you had your water pump and thermostat housing replaced which sorted your overheating problem, may I ask you how much you were stung for that work please and was it recent? Also, were those 2 parts combined together as when I put my registration no into a local parts supplier, you could buy them as one unit but im sure the garage said for my engine it would be separate items? Is/was yours exactly the same engine as mine, ie 2L, TSI, DSG, PPack?

Hi. Mine is the CHHB engine code of the EA888 unit (non PP) whereas yours been a PP is the CHHA engine code, but yes other than that i think engines are exactly the same. The thermostat housing and waterpump are the one same unit made of plastic!(they come in 2 different parts but are removed and replaced as a single unit if that makes sense?). Its a pig of a job as the intake manifold needs to be removed for access to replace the part. I got mine done in main dealer (Ireland) and the cost was 1200euro but I got goodwill so it cost 650euro in the end. My car is 2013 and it was replaced in 2018(?) ish.
Whats your next plan of attack?

[CanaryRossi46]

Hi thx for reply

Well depending on what my auto electrician mate comes back first with ie my options ref a repair/replacement ecu, i may end up taking it to main dealer which i really wanted to avoid but upon hearing your gesture of goodwill story about water pump/thermostat with them basically reducing your bill by half, that sounds more encouraging. How did you get them to agree? I'm guessing that they accepted it was a known fault maybe......if so I havent checked but has there been any recalls on these engines for this?? What was mileage on yours out of interest? Also were there any other stipulations that they required, ie full main dealer service history, etc for the goodwill to come into play? As obviously the std 3yr manufacturer warranty would have expired...

[Carbon VW]

My warranty was out by a good year of not 2. I bought the car new from that dealer and had it serviced there for the warranty period of 3 years. The goodwill came as I’ve been buying new cars off them for the last 15years and I told them it would be the last if they didn’t offer goodwill. I’d say goodwill in your instance is a very slim chance. As you say it is a very well known fault, was even a recall in some countries. My mileage was around 75,000km when it happened. Good luck anyway and let us know how you get on. I assume your not driving the car in it’s current sad state ?

[CanaryRossi46]

Ok I can kiss goodbye to any goodwill then.......I bought mine from a non-main dealer approx 150 miles away and altho i havent had it serviced by my local vw dealer, i entrust this in the hands of a master tech (former vw mechanic) who has looked after all my gti's for over 20yrs. Hopefully my auto electrician mate will come good as apparently if its just the software thats failed i think it can be reprogrammed?? To top it off, once the water pump/thermostat gets sorted, it also has 2 small oil leaks, one from timing chain cover along with what looks like a bad seal around sump 😫 despite having gti's for over 20 years (had mk2,mk4 and now this) i thought this was the best especially DSG but im really having serious doubts over VW build quality which is what they've prided themselves on......