Engine Fault Light - Not Registered

[TriGGER]

I've taken my car into the garage today for an MOT and a service. Also recently I've had my engine management light come up on my car.

Whats worrying me now is that there is no record of the engine management light on my car from VW?

Has anyone else experienced this?

[iforland]

Having worked on software used in the automotive industry it's standard practice for intermittent faults to be cleared from the memory of car electronics after a number of power cycles (starts of the car) if the fault doesn't re-occur. That's probably whats happening here.

[TriGGER]

But why would you design such a fault into the system when you could really be neglecting the start of b fault which could be picked up prior to further slow undetectable damage?

[iforland]

The problem is that sometimes a condition occurs that causes a fault to be triggered incorrectly, it maybe as simple as losing power mid-way through a test sequence or damp in a connector, you have got to remember that a car is quite a harsh environment for electronics. If the fault really does exist or is an true intermittent fault it will either be constantly failed or will re-occur before the first occurrence has been reset. If you read almost any forum for modern cars you will find examples of people "fixing" faults simply resetting the flag, that's not fixing anything, it's simply turning off the light.

I now work in the aerospace industry on electronic controls and an identical process is followed.