E60 540i not starting when engine hot

[ouroesa 0]

Hi guys/gals,

I've read through a lot of posts on this forum and others but have not seen a solution to my issue. 

The vehicle starts fine when cold and runs fine. It is only when I drove it for 30mins+ when it doesn't start for about half an hour after which it starts fine. The dash lights, radio and fans comes on as normal but when pushing the start button, I get one short and fairly quiet beep - that's it. Jump starting does not work in this case.

It is not a battery issue - I have checked. Everything else works fine.

Any assistance would be greatly appreciated, thanking you in advance.

[Olaf 3321]

Welcome.  When you say you’ve checked the battery, what did you do to check it?  

If your battery is marginal, having fans/lights/radio on when you’re trying to start it only exacerbates the problem, as these items rob current from the starter circuit (Kirchoff’s Law prevails).   

Still, the battery may be a red herring.  Suggest you get it scanned by a BMW specialist, they can look at the stored codes and diagnose, and or fully load-test your battery and charging system (if that’s not been done already).

I could guess at things like cam position sensor or crank position sensor, but that’d be foolish and encourage you to load the parts cannon!  

Hope that helps.

[ouroesa 0]

Olaf, thank you for the response.

I leave the vehicle on charge most of the time and the charger has a function to check battery health. Also had the AA once look at it who said it was fine. Logic also tells me the battery shouldn't be an issue as it starts fine when it cooled down. I have an el cheapo code reader, will plug it in and try to start the car with it plugged in - hopefully it will throw some error codes as there seems to be no fault codes stored. Will the car start fine when cooled down a bit if it was the crank sensor?

My first inclination was the starter motor busy dying. Seems like I'll have to take it to the dealer - seems like the car has been there more than at home.

[Young Thrash Driver 1020]

You will need to have it scanned by someone competent. Even if you got a professional scanner (to avoid the bogus returns that the cheap readers can generate), the results can still lead you down the garden path. Case in point, Tauranga Auto Electric told me that when they began troubleshooting a fault I had, they were getting a seat back locking fault code- a convertible specific code, and the vehicle was a sedan.

[ouroesa 0]

I have decided to take it to EuroService - dropping it off tomorrow. Will revert back with a solution as soon as I have one.