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John, ASE Master Technician
Category: Audi
Satisfied Customers: 614
Experience:  ASE Certified Master Technician, ASE Certified Service Consultant, 22 years professional experience
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I have a 2001 Audi a6 2.8. now both c(?) converts were

Customer Question

I have a 2001 Audi a6 2.8. now both c(?) converts were replaced all o2 sensors was replaced .still have codes P1110 and p thinks computer might be bad because 1 o2 sensor was shorted out .any ideasatalic
Submitted: 2 years ago via
Category: Audi
Expert:  John replied 2 years ago.


My name is***** see what we can figure out. Are you just looking for info to see if the shop is correct? Or do you want to try to fix this yourself? Please feel free to ask any questions you need to get to the answer you need. I only get paid for my time if you rate my responses positive in the end.

The codes P1110 and P1105 indicate that the rear (after catalytic converter) oxygen sensors are shorted to battery power somewhere on the heater circuit for each sensor. If there was a shorted sensor then there could be damaged (melted) wiring leading to those sensors. Or something could be wired up incorrectly.

The shop (or you) should be able to check for battery voltage on the heater wires with a multi-meter. The heater circuit should only show power when commanded by the engine computer so this should be easy to find. If the key is turned off then the computer should not be telling them to turn on. This just simplifies the issue. So now they can simply test the heater circuit wires for battery power (which should not be there with the key off) and trace it back to the source of the short. There are other possibilities that could cause this but this is where I would start.

If they installed 'universal' oxygen sensors or incorrect sensors, then a wire may be crossed somewhere so I would double check for correct wiring. If needed, I can provide the correct wiring with wire colors for those sensors.

Lets start there and see where that takes us. Please let me know what you find out and I will keep at it until we have a solution.


Expert:  John replied 2 years ago.

Hello, just following up to see what you found.

Thanks, John