A3 2.0 TDI 2010 won’t start in hot sunny weather

[Adrian Brown]

Audi A3 2.0 TDI 170 BHP year 2010

In hot sunny weather (say +25 degrees) the car will not start. It does one of 2 things. 1/ instrument cluster lights up and then goes dead (there is power everywhere else; ie; windows, lights, radio etc etc). 2/ starts and then cuts out within 3 minutes. The car will not start afterwards. When the temperature outside cools it starts and runs perfectly. It runs all winter perfectly and passes MOT’s with no advisories. Parts replaced so far; battery; ignition switch; starter motor; genuine Audi instrument cluster; still not resolved issue. Audi UK have had car twice (they replaced cluster) and nothing comes up on their computer. Anyone had this issue? I am able to do most things but dont know what to do next. 
Many thanks; Adrian 

 

 

 

[cliffcoggin]

Adrian.

My first thought was the instrument cluster but as you have had that changed I am at a loss to think what else it could be. Did Audi have any suggestions, or did the problem not happen while the car was in their hands? Sadly the reliance on diagnostic computers has eliminated the human brain as a means of tracing car faults.

[Adrian Brown]

Audi have no idea either. Because the diagnostic did not reveal anything they are as confused as me. I have shown them videos of the fault. I thought they might have a data base centrally they could access; but no. Thanks for your time. 

[cliffcoggin]

Thinking further on the matter, perhaps speculating further would be a better description, if the problem is outside temperature dependant I would investigate how and where that temperature sensor affects the ECU. I reckon there must be an temperature input to the ECU so that it can compensate for ambient air temp variation, but the details of how that circuit operates are beyond me. I suggest an auto electrical specialist would be the best option at the moment, because I have been distinctly unimpressed by reports I have read on this forum regarding the diagnostic abilities of even Audi main dealers. As I said before, if the computer says no, Audi are stumped.

[Adrian Brown]

Great point; i will investigate this idea. Fault ONLY happens when its hot and sunny and car is always outside. I wonder if it would happen if parked in garage and then taken outside into hot sunshine ( i expect not).  The dash top is too hot to touch when outside is +25 degrees (much hotter in car). I think something under dash is affected by the heat and therefore causes issue. I note the ecu is located under the wipers at front of windscreen. Does  this supply 12volt to the cluster?  As stated if i go back in the evening when cooler; all starts as if nothing happened. Stopped calling RAC as they are unable to get it going. Thanks for reading 

[cliffcoggin]

Please do let us know the outcome. The information would be invaluable for future reference.

[audia4b5kev]

ECU    BUD   MATE  HAD SAME BOTHER   KEV

[Adrian Brown]

If i get a used ecu will this need to be programmed into my car; or can i just swap them over. 
Thanks

[audia4b5kev]

as long as you  get  every thing it is plug and play   kev

[alesandro197]

I have some problem 

Audi A3  19 TDI  2009 

Help me.

[Steve Q]

2 hours ago, alesandro197 said:

I have some problem 

Audi A3  19 TDI  2009 

Help me.

Have you done a diagnostic check to see if any fault codes flag up? 

[alesandro197]

yes but when it gives me the problem that it is hot it gives me multiple errors

[alesandro197]

Sorry for my english 

[Steve Q]

2 hours ago, alesandro197 said:

yes but when it gives me the problem that it is hot it gives me multiple errors

What are the errors? 

You're English is good don't worry🙂 if you're getting various codes could there be an issue with the battery? 

a failing battery can throw up all sorts of electrical problems. If the battery is 5-7 years old or older then it could be starting to fail. I'd recommend a battery test. 

[Audi-Inny]

I have had this exact issue. It started at the end of a hot summer last year. Possibly 100 degrees out in Las Vegas. It was 112 and stayed up there weeks before. My car stalled in the middle of doing 45-50mph on a busy three to four lane road. Dash lights went out. I pulled over into a gas station, decided to get gas and car would not start. Dash lights came on when turning key. Then after a few minutes of panicking at the gas pump (stuck there) under some shade, it started. Then drove for about 5 minutes and it happened again. Kept on cranking it. Then after maybe 5-10 minutes, I was able to start it and made it home about 5-7 miles. Thought it was my battery. So I recharged it. Battery was fine. I decided not having my AC on because I suspected alternator/battery. This was the end of August, I think? Then it happened again just recently.about a month ago. (March/April) it kept happening 5 or more times after that. That’s 5 different days. Tried jumper cables with whomever would come to my aid. Same thing if I let it cool down. It will start and run another 3-5 miles then stall. Bought a new battery and it wasn’t that. Changed the voltage regulator on the back of the alternator, still stalled. Changed the fuse box, made sure the battery cable was grounded to the chassis, swapped relays, a few of them (under steering column, checked fuses, all good. Changed coolant temp sensor and ignition key tumbler. And it still happened. I scoured the internet for insights on the matter, and the only thing left was to change the pcm/ecm/ecu. (The cars computer) I’d have to get a preowned ecm and send it along with my factory one to have them clone it for the immobiliser. This is current as we speak. It seems that my cars computer probably got too hot. The car was originally from Arizona. (another hot weather state here in the U.S.) my car is a 2011 Audi A3 8P. I even hooked up a voltage battery digital meter in my car and it read 14.1v while the car is running. And 12.6 when the car is off. It’s weird that I stumbled onto this topic. Because I read a lot but nothing exactly like yours (OP). In the winter I had no issue with headlights on, and foglights, heater. And it would be parked in the garage. The most recent stall happened early in the drive home, when I left my car out on the driveway overnight. In the sun. It stalled much earlier. But mornings, when I drove to my job, I stressed out a lot but, it wouldn’t stall. It was when I drove home around 4pm everyday, when the weather was at its peak during the day. Sorry for the long post. But I needed to let others know that this is a thing. And it’s dangerous. I would imagine getting stuck on the highway/freeway. And no one letting me pull over. Because the hazard/emergency light wouldn’t work right away. I would have to turn off the car, and turn it back on to get them to work. And you know what that means. ‘Steering wheel locked.’ So I’ll post after the remedial process is done. For now, I’m already in the process of installing a small online blower where the ecu is. And turn it on when the car reaches normal running temperature. Good Luck All. If you happen to run into this problem. WIP…

[cliffcoggin]

Thank you for the information Merlin. Please let us know the outcome.