Hi Many thanks for your help, as I really need it. My VW mechanic mate has looked after this car with incredible detail, ever since I took ownership of it 4 years ago. Accordingly, he changes the fuel filter every 10,000 miles. Fair point on fuel and air lines, will get him to check. tank lift pump has merrit, but does not explain the pathology of this fault. IE the car drives fine for the school run, IE for about 45 minutes driving,, never an issue, then park up and sometimes, but not always,, the issue arrises, either within a few seconds of starting up, or about 100 yards, so always once the car is at running temp and has been left for a while. I would think that a lift pump issue would strike at any time and not be temperature related. I don't think it is the injector pump, I had one go on a previous V6 Tdi, at 80 MPH in the fast lane of the M40 only just made it to the hard shoulder. I have never heard of one functioning again, after it packe up. That one cost me £750 and my mate fitted it for £250, VW wanted £2.5k to do it. I almost wish it was this, because The car is in stunning condition, plus I know everytything that has beend done on it..

Many thanks Cyd and I tend to agree. My mechanic mate said he was going to check the wiring out, because we both believe it is down to the signal getting lost and causing it to cut out. He said he replaced it with a genuine VW part to be on the safe side and is going to get it exchanged, just in case it is also faulty, though I doubt it is. I am wondering if the wires can be replaced to be on the safe side, or do they dissapear into a massive loom, which would then be a major op?

Thanks for the info on the method of testing. That would be one for my mate to do, if it packed up on him, because all testing needs to be done at the time of break down. Once the cam has all closed down, there are never any faults registered in the log, the only reason we got the fault code the last time it broke down, was because the AA guy turned up so quickly and managed to get the code, which he gave to my mechanic mate.

One question. Why would this happen only once the engine has heated up and then cooled down a bit?

I tend to agree, more desparation than anything and Mike was going to get it on warranty, but I think it would just be a waste of time, as it is highly unlikely. I will let Mike know about the external wiring option. Could it not be the ECU ? The problem is it cuts out so rarely and randomly that it is extremely difficult to have the diagnostic system to hand, which is partly why it has been such hard work to pin it down. Thank you again.

Find someone with VCDS to help you. Take the car for a drive with someone with VCDS in the passenger seat monitoring the engine measuring blocks. When the engine cuts out you may see the reason why. At the very least you should be able to eliminate what it isn't. Fuel temperature sensors have been known to fail on these. Although they're inside the pump it is possible to change them. Also using VCDS check the fuel pump base timing. This can be done with the TDi timing tool in basic settings. The timing reading information is gathered from the needle lift sensor and the fuel temperature sensor, the values of which will be displayed on the PC screen.

Edited by Railroad. on 16/11/2016 at 09:17

There's a lot more to VCDS than just checking fault codes. The reason why your engine is cutting out may not even generate a fault code. The ECM will only generate a code if something falls outside of its programmed parameters. VCDS is very comprehensive. You can do live data monitoring in both digit and graph form.