Automatic gearbox wont start when it is hot
 

I have a very strange problem.AUDI A4 B7 automatic ( 2007) car starts normal when it is cold, but after 10 or 20 minutes of driving , when car is stopped it can not start again. I need to wait about half an hour to start it again. It does not crank.There is no error codes, everything seems normal. I suspect that fault is in temperature sensor, but it was replaced a week ago. Transmission simply skips P and N position. Oil in gearbox was replaced, temperature sensor was replaced.

Any help, clue ?

Had a similar problem on another car. Turned out to be a bad starter solenoid (with a missing heat shield). When the car got hot the solenoid would not work. Ended up replacing the starter and everything was fine. Not sure if that will be your issue, but worth checking out.

Thank you for a hint. I've bought a new solenoid ( 19€) and it will be replaced tomorrow. I'll let you know if this is a reason.

It was not the solenoid. It seems that electronic in automatic is the reason. When oil in TIPTRONIC gets hot, it prevents to start the car. Do not know what to do

Could be a faulty neutral safety switch as well. Not sure how expensive those are to replace. They don't look to difficult to replace from the pics I have seen. Might be time to visit a transmission repair place and get their thoughts.

Hi, did you ever solve this as mine is doing exactly the same?

I got the same symptoms on my 2003 2.0 CVT of 'Not starting when the cars hot'.
BUT there was a CEL light on the dash & it turned out to be the crankshaft sensor.
When it goes bad it stops working at about 40°C. But goes bad a bit under that.
So you might start it, get the CEL & it runs bad, then stop the engine & it wont start untill its cooled down again.

My cheapo ( corded ) OBD2 scanner told me exactly what it is.
If you haven't got a scanner, got one, even a cheap ones better than none & theres good , real cheap, windows via USB with disc for a computer versions out there too. KKL or something. Great if you have a laptop.
The Bluetooth/wifi one i had crapped out pretty quickly & depends on your download & anything free wont get you much info.