emissions warning light

[lee_tracy]

Hi all, i have 2001 polo gti, the trouble i am having sometimes is the emissions warning light comes on for a few secnds whilst driving, it then goes out and the car drives fine. The light may not come again for a few months, then bang on she pops. I have had the throttle body reset at the local vw dealer, the car has gone through the mot last week, so i know it cant be anything too serious. It just pops on and off randomly...The car drives perfect at all time???? any ideas

[towcestervag]

get a diag test done to see if any faults logged
it could be just something simple or a remap

[lee_tracy]

Been down that road already, the vw dealer said that unless the light was on when it was hooked up to the machine, then no error code would appear as the ecu would have done a self test and reset??? So reluctant to give them cash if no diagnosis can be sought???, this problem is completely random and the car can run fine for months and months???

[idealsam]

Probably unlikely to be the same cause but I had a similar problem. Had a new lambda sensor put in but it was still happening. It was a little worse than your case as the car would start misfiring and eventually get so bad it could hardly get up hills. In the end I re-replaced the HT leads and it started running fine.