The CEL on my wife's 2000 TT quattro (42K miles) recently came on. The car's performance seems to be unaffected. Advance Auto read the code as P1128. My Bentley manual lists the following items in the overview of this code.

- Exhaust system components (O2 sensors)
- Fuel injectors checking
- Fuel pressure regulator and residual pressure checking
- Fuel pump checking
- Intake system for leaks (unmetered air) checking
- Check vacuum lines for proper seal
- Secondary Air Injection (AIR) system components removing and installing

Has anyone had a similar experience with this code? Is there one particular item on the list that is a more common failure than others? Any serious advice would be greatly appreciated.

 

maybe a bad O2 sensor, I know it only has 42k on it but I'm sure they have never been replaced and with 6 years on them there the first thing I would think of.

 

o2 sensor should make the performance degrade or put the ecu into limp mode. I think most likly it will be a vaccum leak check underneath your intake head there are a couple tubes running into it which often get brittle and break you will have to remove all the plastic from the front of the engine to get to them.

 

doesn't sound like the O2 sensor diagnostic chart says air leak which would throw that code, the O2 sensor is doing its job in reporting a lean mixture in bank 1,

probable causes are injector(s) leaking, intake/exhaust leak, AIR system - hose leak