Limp Mode recovery?

[LloydL]

1998 Jetta TDI

following a limp mode shutdown to idle-only mode after 120km of high speed driving, with MIL showing fault code 00777 (Accelerator Position Sensor) and blinking glow plug indicator, and a tow home, the code was cleared and the accelerator pedal is now functional, at least for the very short distances and times that I have comfortably driven to check for recurrence of any fault codes. none have reappeared. have others had any similar experiences, and what reliability should I expect for driving any substantial distances?

[6eggs]

So the problem was fixed when you cleared the code? Make sure all the grounds are good and the battery is good.

[little racer]

Had similar problem code came back three times. In the end it was a damaged cable on accelerator position sensor plug.

[LloydL]

6eggs - I don't believe that clearing the codes had any affect on the problem. anyway, the MIL returned today (65535 only) on a 3 minute drive. the battery is good, and thanks for the suggestion to check the grounds.

little racer - was each occurrence of the three error codes accompanied by a limp mode shutdown (or some other vehicle problem)?

thanks to each of you for the replies.

[Seatman]

I had this sort of problem on my seat cordoba on a 2000 plate 1.9tdi. It actually turned out to be the ecu had got damp and it was shorting out where the big plug goes on. I had to open it up, clean some slight crud off the contacts and give it a good dry. I have since sealed it with silicone and wrapped it in a bag and am pleased to report I've never had the problem again. I don't know how relevent or helpful this would be to you but thought I would post it just in case. I'd bought a new throttle position sensor to.

[LloydL]

to (possibly) address the 65535 fault code, I pulled and opened the ECM. consistent with many other posts on the topic, the section of vacuum hose MAY have been the ECM problem - it was bowed, slightly pulled back from a fully attached position on the metal nipple on the side of the ECM, and about 1cm on that end of the hose was much softer than the remainder of the hose. I replaced the hose with a 3mm ID (soft, rather than firm) silicone hose from McMaster-Carr. the car's been driven 40 miles thus far with no recurrence of a fault code - a repair (knock on wood) costing pennies rather than an $1800 replacement of the ECM as suggested by the VW garage.

as for the accelerator pedal position sensor, that may still remain a problem under circumstances of longer range, steady high speed driving. a replacement part was ordered from World Impex.