Hi, I have an odd problem with the car which is a Mk1 Vrs, The ECU light has come on and also with that the fuel gauge is moving up and down on its own and also the MPG on the trip computer has died, Is it worth doing a manual reset on the ECU to see if that fixes it? The car drives fine other than that. Thanks:confused:

Sounds like a problem with the tank sender, the ECU and trip computer are unable to establish how much fuel is in the tank due to the wildly varying guage.

Ok, Too be honest i did not notice the fuel gauge doing this at first, I saw the ECU light come on and then after 10 mins or so the low fuel alarm came on which was odd as there is 3 quarters of a tank of fuel, Then it wavered back up to halfway, Looks like its gonna be a pain:(

it could just be a loose connection, or water may have got onto the connectors causing the resistance to vary. Hopefully thats all it is, but tracing the fault will be fun. Lets hope its not a problem inside the tank itself.

Funny thing is the trip computer still tells me the range left in the tank althought the MPG is dead? If it was the sender would it know the range of fuel left?

The remaining range is an approximation based on the last 20 miles or so of driving possibly less. its quiet possible that although its telling you something it could also be way off. The MPG is calculated in a different way, based both on fuel remaining and the fuel flow rate, the ecu cannot make any sense of the figures its getting so has thrown a fault code.

Getting the fault code read, should reveal the exact cause of the problem. Either a dealer or someone with vag-com can read the codes from the ecu. There is a list of member with vag-com on the forum, have a look to see if anyone is near to you.

http://briskoda.net/diagnostics-vag-com/vag-com-owners-map/80992/

Edited 20 February, 200917 yr by mannyo

ECU reader says vehicle speed sensor is shot so have ordered a new one, Will let you know as speedo has now died.