A6 Quattro 1999: Low Catalytic Activity p0422 & p0432-
Background: 140,000 miles
1. Passed inspection here in NY, threw the first code about 50 miles later.
2. I just bought the car, last owner says the Cats were replaced about 5,000 miles back.
3. The car runs like a dream, but there are a couple of other things that aren't helping me diagnose this thing. Namely, the coolant temp sensor isn't reading on the dash (circuit broken?), and the digital screen that tells you engine efficiency and what gear your in is schizo (looks like it might be reading 18 mpg, or 10), but I can't tell the values until it's replaced.
4. I've turned the codes off (obdmeter), and they do come back about 50 miles later.
I understand that bad mileage could mean bad o2 sensors, and these should be replaced pronto. But I need the screen to work to prove low mileage. Don't drive enough to notice (NYC). Display replacement: parts or how do I do this? I need to know how to get the mechanic to diagnose this right so I don't replace cats and get the same code.
Any experience out there with this particular problem?
Could the temp sensor have something to do with it?