Needle Lift Sensor Problem (or Not)

[jonrev]

Hi, Wonder if anyone can help. Bought this Alhambra 1998 TDI a few weeks ago. Was told it had just had fuel filter changed to rectify a fault and that there was air in the system still as it hesitated occasionally when the tank got low on fuel. Sure enough on the drive home I felt it hold back sharply a couple of times and the glo-plug light started to flash. Filled the tank and cancelled the fault light (vag com) no more problems for the last 250 miles. Yesterday with the tank nearing half full the glo-plug light on the dash started to flash and the car started to hesitate again.

Vag com reports '00542 Needle lift sensor- implausible signal- intermittent'. So is it likely the needle lift sensor is faulty or is there some fuel related problem which is causing the sensor to show up as faulty? Could air in the system be causing all this bearing in mind that it only occurred when the tank was half fullish. Or has anyone any other suggestions. Any help would be gratefully received.

Thanks

[seatkid]

Probably the O ring on the T-piece in the fuel filter top is missing/damaged/not seating. Common cause for air getting into supply pipe causing misfire/hesitation under load. Remove the mickey mouse clip to lift the t-piece and check.

[jonrev]

Thank you that's excellent. Was hoping it would be something 'silly' rather than expensive. Been used to less complicated cars. Just sold my trusty and simple old Transit to get this Seat as I needed a tow-car for our recently acquired caravan. Guess simple cars just aren't available any more so it's a case of plugging in a computer, reading off the fault codes and buying expensive spares to swap out only to find it was something daft needing tightening all along. About the only bit of technology I really couldn't imagine being without now is this PC and it's connection to the net. Sites like this and the helpful guys who offer their knowledge really are invaluable. Thank you all.

PS I'll let you know what I find as soon as I get the chance.