Volkswagen Repair: Engine light on, plastic casing, speed sensors

Question
I have a '98 Jetta GLX, automatic, 6-cylinder.  The engine light came on about a week ago.  It is not flashing and I doubt it's the gas cap (it could have something to do with the cars emissions).

Last night my brake light came on (while driving) and also my ABS light came on while driving and stayed on.  I just had a new ABS system installed less than a year ago.

The car is driving fine and the last time it was in the shop, the mechanics said my brakes were fine.

The car is going into the shop in a few days, I just want some suggestions.  I'm thinking there is something going on with the diagnostic system.  (When I got home, I turned off the car and turned it on again and both the ABS and Brake lights went off. The engine light remained on.)

Thanks.

Answer
Well I am thinking that the engine light and ABS/Brake lights are 2 different problems.  Both can be read using a VAG-COM tool.  Since not all of us have them at our disposal I'll go over a few quickies.  

Engine Light - as you have already found out the gas cap can cause it, and also anything from a bad O2 sensor to engine over-speed.  A flashing engine light is bad and VW doesn't reccomend driving with a flashing engine light.  If the car is running good I'd say just drive it until you can get it in for a diagnostic test. Unfortunatly the light can only be cleared with the proper tool.

Brake/ABS Light - Fluid level?  Did it only do it once?  If it happens again you should inspect the wires that run from the inside of the fender to the wheel speed sensors. I had one that rubbed away the outer plastic casing and began shorting out, made the lights come on as you describe, and the lights would only go out when the car was shut off and restarted.  The ABS ECU also stores codes and can be checked at the same time as the engine light.

Heres a trick, if you take your car to VW and get a "summer maint. package" they will do an oil change, filter, lube, and pull the codes for yah for like $60.  If you take the car in and say you just want the codes pulled then its like $100 just for them to hook it up.

Good Luck
Ryan