Hello
 

I am having trouble with a 1994 Audi 80 Avant with the ABC engine.
The engine shut off while driving and has not started again (battery fine and a strong crank), I have read the engine with a VAG computer and it gave 518 (G69) Throttle position sensor (sporadic - short circuit to earth) and 555 G108 Oxygen (lamda) Sensor (sporadic - impulsible signal.)
I installed new original Throttle position sensor and cleared the codes. The codes are now gone even after a lot of starts an no codes to read now.

There is fuel in the fuel rail, spark from the spark plugs and 10 volts at the injectors.
I hear the fuel pump (I change it after the car died just in case) and have also jumped the fuel pump relay.

Seem to be some sensor or computer error I think but as I said no codes now from the engine.

Does anyone have any suggestions on what might be wrong and if it is possible that it is the camshaft sensor without code?
I had the same problem (no start when cranked) maybe 8 years ago but then the engine gave a code for the camshaft sensor and that did the job.

Yep could be the cam sensor. Did you change the lambda sensor when it threw up a code? 

Thanks for the reply!

Then is it possible to have a broken cam sensor but no code?
No, did not change the lamda sensor, could a bad lamda sensor cause this?

Hello David,

1994 would be very early for reliable diagnostics, so personally I wouldn’t attach  too much significance to the ‘no codes’ diagnosis. The old adage is that if you have compression, fuel and spark, then you would expect it to start, subject to a good cranking speed, and the sparks arriving at the correct point! 
Steve could well be right, and I feel you may  just have to substitute sensors on a trial basis. 
Kind regards,

Gareth. 

Thanks for the reply!

Will order a new cam sensor and report back.

If anyone has other suggestions, please let me know - Thanks!

I changed the cam sensor but still doesn't start.
Any ideas?

Check the engine ecu. It's by the glove box. These can get wet and fail.