reject902

Hey guys, I'm having some code issues and I'm a bit confused..

Anyways, here's a short run down of what's been going on. I have a 2002 A4 1.8L Quattro @ 182k that I've been the owner of for 5 years. My car lost most of it's acceleration and thew the MIL light a month or so back. Took the car to the stealer, and they suggested new cat and crankcase hoses, as the codes wouldn't stay cleared and they could see it really lost its power. Had the cat, hoses and check valves replaced (not at the dealer, but an indy shop) and drove fine for a few days. MIL light came back on and I ran the codes with VCDS again. Same codes came back again after maybe 20 miles. These codes are the same that I pulled when I took my car to the dealer the first time.

I initially thought maybe I needed a new pre-cat o2 sensor. The only thing is, the code thrown shows as Bank 2, Sensor 1? There's so much reading I've done on here and my mind is maybe a mess right now, but isn't it that my car only has a Bank 1? Would I be looking at a bad ECU then?

Oh, and I wanted to add too that when using a generic hand OBD-II scanner there's a change in codes. I still get the cat threshold code in generic form, but I also get a "system too lean" code, which isn't present in VCDS. The hand code scanner as you can see is also missing the o2 sensor code.

And on another odd note, I pulled the saved codes I had from a scan on June 9th, and there was another odd code in VCDS that was thrown that also wasn't on my hand code scanner at the time and shouldn't apply to my car. (aka its not a disel engine)

After that clear I never saw it again..

I don't know what I'm dealing with here. Bad ECU? VCDS not working correctly? Any ideas?

And now I have another new code..

Today's code pulls were:

Any suggestions are greatly appreciated..

Thanks,

heateris

Sounds like you need a MAF and both O2 sensors.

reject902

Well I just got back from the dealer.. They replaced some crankcase hoses which were throwing the lean code and checked everything else out. They said the MAF & o2 sensors were operating to spec.

10 miles later, the check engine light is back on.

Same code as before:

16804 - Catalyst System; Bank 1: Efficiency Below Threshold
P0420 - 002 - Lower Limit Exceeded

So now that they have "ruled" out everything else, am I looking at a new sick cat? It's a Catco #4186 converter that the exhaust shop put in. Has anyone heard of any issues with these cats as far as any false sensor readings and that? I'm finding it hard to believe it could be bad. Although, manufacturing defects due occur.

heateris

You probably need a better quality cat. You could also try a spacer on the rear O2 sensor. 034 motorsports sells a decent spacer for about $20.

Pete@ECSTuning

I'm glad your phantom second exhaust bank went away?! That was curious. If we are down to a bad cat code - as you have posted. I would suggest an direct fit catalytic converter instead of a universal cat.

We have direct fit catalytic converters that have been very successful. Quite possibly the nicest thing about our direct fit catalytic converters are that you can install one DIY style. You don't need an exhaust shop to cut or weld anything.

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