The issue is I was having some misfire errors and I had a valve gasket leak. The mechanic and i decided to replace the ignition coils and the sparks plugs while doing the gasket. What we did not know is that the harness for the engine was beyond brittle and during the process suffered some damage, and since then we have found damage to the harness elsewhere. The majority of the damge is broken doown insulation and some broken strands of wire. The harness is still intact.

With all that put together, the engine is now having alot of issues, all issues being very random. Does anyone have any past experince or opinion on dealing with a fragile engine harness. Can a harness be tested with a diagnostic?

 

I had to replace part of my harness for the same reason. The bit that led to the ICM was brittle and cracking, and as a result the car wouldn't start and the ICM was throwing error codes. I had the damaged part of the harness replaced and cleared the codes and everything was fine.

For a more direct answer to your question, no, the harness itself will not throw codes or a CEL, but the piece of the car that it is having trouble talking to will. This could be helpful in diagnosing where your issues are coming from.

Also, for more specific advice, it would be beneficial to know the model year and motor.

 

The model is 2001 A4 1.8t Quattro AWM

 

I'm not sure if it would help, but I've got an extra harness from a 1.8T AEB.

 

IIRC, it's a different harness. AWM has VVT, AEB does not.

I have had to replace entire harnesses before due to corrosion or rodent damage, but not on an 01. That's unusual.