With my 2000 Octavia TDI, I expereinced that the engine fails to start, especially when it's warm - driven more tham 2 - 3 km after a cold start. At a few occations, the engine has also dropped dead when driving - a complete power loss.

Using the VAGcom, I got error at the temp.sensor: "17664 - Engine Coolant Temp Sensor (G62): Open or Short to Plus

P1256 - 35-10 - - - Intermittent"

Well, today I replaced the sensor, and surprisingly the same thing happened again. At that time I had my laptop with me, and tried to use it to see if there's another faultcode. However, I could not establish contact with the car. After some time, the car started again, but no faultcode was logged.

The loss of contact with the car, makes me suspect that there is a serious problem with the onboard controllers, causing this erratic behaviour. Anyone else that experienced something similar, or maybe someone has a hint?

Could be the 109 relay, this can cause stalling problems and I think starting problems too. it cojntrols the glow plugs and power to the ECU IIRC.

I seem to remember there was a thread about hot starting problemstoo, try a search.

I'd agree with trundlenut on that. Relay 109 is the X relay, when it fails it causes the engine to stop.

Thanks for feedback.

I've replaced the relay 109, and have driven (and started) with no problems. Seems like this was the cause of the problems.

I'll post a follow-up if the problems should re-occur.

-Rolf

Hot start issues can also be caused by a stuck EGR/anti-shudder(?) valve too, so if problems continue it might be worth checking that out too.