My car will start OK when cold, on the first or second attempt. It will start on the 1st attempt if the engine has been running, and the engine has only been shopped for a few minutes.

However if the engine has got hot, and then have been stopped for say 15 minutes, it can be very hard to start. Sometimes I even have to leave it for half an hour, and then it will start 1st time….

Why? What is going on?

With a bit of googling....

Some people say it may be due to the ECS wanting the engine to be turning over fast before turning the diesel ejector on when the engine is hot. But it mostly seems to be lots of parts being replaced until the right part is replaced to fix the problem, but it is a different part that solved it in each thread I found.

http://forums.tdiclub.com/showthread.php?t=116576 for example, but these seem to be a lot older then may, so the software may have been changed.

However these all see to be people having problems with hot restart, rather then when the engine has cooled a little.

  • Even VW experts will need a lot more specific information to properly diagnose this, as it can have a variety of causes. The first thing to look at is the condition of your battery. Your vehicle needs more cranking voltage when hot than is expected.
    – SteveRacer
    Commented Jun 1, 2016 at 14:23
  • @SteveRacer, the battery was replaced last year. The odd thing is that it start OK if the engine is hot, but not when it has been left for a time, unless it has cooled down a lot. Commented Jun 1, 2016 at 14:32
  • Check your temperature sensors, that's one of the many things that can cause such problems. And crank and cam timing. I suggest you google "VW diesel won't start hot" and do some research. There's way too many variables to troubleshoot this from my chair. There's some solid VW techs on here; maybe they can chime in.
    – SteveRacer
    Commented Jun 1, 2016 at 14:57
  • Is the timing (belt) correctly set? Commented Jul 23, 2016 at 21:37


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