There seem to be lots of this happening in this forum and the things suggested vary a lot between each thread but I don't think any of the solutions obviously apply to my car.

 

Cold start is always fine, however, once hot, not only does the Start/Stop not usually work (it sometimes does) but also starting from parked sometimes also takes 2 or 3 tries. A few times, I haven't been able to start the car for like 30 seconds and it seems like luck when it eventually starts - very weird for a diesel.

 

My local VAG specialist (not main dealer) says there are no faults logged and that the battery tests fine (although it seems to turn over OK, it just doesn't start so not sure it would be the battery?). The only weird thing I have noticed is that sometimes, the start stop system doesn't stop the engine and the display says something like, "Start/stop deactivated, engine must be running" even when it is running - is there an "engine running" sensor that could be busted?

 

I've seen suggestions like swapping out the starter motor which seems like an expensive risk on a car with only 60K miles on it. I also heard about a cam shaft angle sensor being a potential problem but I would expect a fault to be logged if that is the case?

 

Anyway, I would really appreciate some advice. Disabling the start/stop each time is bothersome and since it defaults back to Normal mode every time you stop, when you switch it to Eco, it always enables start/stop anyway! Also, it would be nice for it just to work as expected :-)

This sounds identical to my 1.9 but I thought the issue had been sorted on later cars (non PD). On mine it came down to some odd coding where a few things combined caused it to not apply fuel. Those being; above a certain temperature; starter a bit worn and not able to crank above a certain speed; maybe one more but I forget.

I tried a refurbished starter, new battery and earth points, a bunch of other things. In the end I lived with it as I learnt that a crank after the initial crank would wake it up and kick it into life. Easy enough with a key start. Not so much with a button I expect.

Then I decided to get a remap. Totally unrelated. The issue was solved. Never came back. Had a chat with the tuner and he reckoned it could have been something picked up by the guy who created his base map.

My suggestion would be to try a map of that's of interest to you anyway. Clearly that is a specific solution that not everyone would want. I'm sorry I can't offer any other advice. You might get lucky or like me chucking a parts cannon at it and still not solving it.

2 hours ago, Lukos said:

There seem to be lots of this happening in this forum and the things suggested vary a lot between each thread but I don't think any of the solutions obviously apply to my car.

 

Cold start is always fine, however, once hot, not only does the Start/Stop not usually work (it sometimes does) but also starting from parked sometimes also takes 2 or 3 tries. A few times, I haven't been able to start the car for like 30 seconds and it seems like luck when it eventually starts - very weird for a diesel.

 

My local VAG specialist (not main dealer) says there are no faults logged and that the battery tests fine (although it seems to turn over OK, it just doesn't start so not sure it would be the battery?). The only weird thing I have noticed is that sometimes, the start stop system doesn't stop the engine and the display says something like, "Start/stop deactivated, engine must be running" even when it is running - is there an "engine running" sensor that could be busted?

 

I've seen suggestions like swapping out the starter motor which seems like an expensive risk on a car with only 60K miles on it. I also heard about a cam shaft angle sensor being a potential problem but I would expect a fault to be logged if that is the case?

 

Anyway, I would really appreciate some advice. Disabling the start/stop each time is bothersome and since it defaults back to Normal mode every time you stop, when you switch it to Eco, it always enables start/stop anyway! Also, it would be nice for it just to work as expected 🙂

Hello Lukos, welcome to the forum.

The 'engine must be running' message just means that the automatic idle stop function has been inhibited and the engine will remain running - there can be a number of reasons for this; low battery charge state/high electrical load, low or high cabin temperature, etc.  

A failing crankshaft position sensor (not camshaft) can apparently cause your symptoms - and may not log a DTC code. 

Hi Everyone,

 

I had the camshaft sensor replaced although I have now just noticed you said Crankshaft sensor! Whoops. Needless to say, the camshaft sensor didn't help.

 

I'm just going to check how easy it is to do it myself. Had the camshaft sensor done as part of a service so it was already in the garage but it looks fairly easy to replace the crankshaft sensor.

 

Thanks

Also, with regards to the "Engine must be running" message, I see a different message, "System load too high" if it was maybe running the radiator fan or regenerating the DPF, and at the time, I didn't have the air con running so I suspect there must be something more specific that would cause this message.

58 minutes ago, Lukos said:

Also, with regards to the "Engine must be running" message, I see a different message, "System load too high" if it was maybe running the radiator fan or regenerating the DPF, and at the time, I didn't have the air con running so I suspect there must be something more specific that would cause this message.

System "Load too High" is just the way VAG flag an indication that battery voltage (SOC) might be lower than normal - this can be caused by frequent short trips, a failing battery, or a faulty charging system.