Bad Cat? Or bad call?

[twcjcarrera]

Hello to all, I am making my first post but have been reading now for a while. About three months ago I purchased a 1999 porsche 911 C2 and it ran well. Literally two days after I purchased it I got the CEL light so I ran it to a local shop where they work on Porsche and they changed the O2 sensor in bank 1 before the cat. The next day after leaving the shop the light goes off and this time the P1123 code went off so I went back to the shop and they cleared it stating it might have had some extra fuel it needed to burn since it was running rich.

The light keeps triggering after a few days and it doesnt vary from P1123 and the car has 48,900 miles on it. I have cleaned the MAF sensor as decribed on a DIY post and the only thing I have noticed while driving it this whole time is there seems to be some slight hesitation on the low speeds like if your driving in 5th gear while only going 10-17 miles an hour.

The shop stated it is a bad or clogged cat and wants to charge 1900 for parts and labor. I wanted to get some feedback from the group as we tend to have a lot of experience amongst the group.

Thanks!

JC :renntech:

[Loren]

Ask them to print out the waveform for the before cat and after cat O2 sensors - for each bank of the engine.

I do not think you have a bad cat with that fault code.

P1123 Oxygen Sensing Adaptation Area 1 (Cylinders 1 - 3) - Lean Threshold

This means your mixture on cylinders 1, 2 and 3 is too rich and the DME can make the mixture lean enough (to meet emissions).

Possible causes are:

- Fuel pressure too high.

- Fuel injector leaking.

- EVAP canister purge valve open.

In most cases that I have seen this is a bad or stuck purge valve.

If you do not feel comfortable working on the car yourself then I suggest finding another Porsche shop and ask them for their diagnosis.

[twcjcarrera]

Ask them to print out the waveform for the before cat and after cat O2 sensors - for each bank of the engine.

I do not think you have a bad cat with that fault code.

P1123 Oxygen Sensing Adaptation Area 1 (Cylinders 1 - 3) - Lean Threshold

This means your mixture on cylinders 1, 2 and 3 is too rich and the DME can make the mixture lean enough (to meet emissions).

Possible causes are:

- Fuel pressure too high.

- Fuel injector leaking.

- EVAP canister purge valve open.

In most cases that I have seen this is a bad or stuck purge valve.

If you do not feel comfortable working on the car yourself then I suggest finding another Porsche shop and ask them for their diagnosis.

Thanks for the quick response! Couple of questions,

1. Fuel injectors leaking i assume would be visible to the human eye if I start looking around the fuel rail?

2. Is there a DIY pictoral view of the EVAP canister purge valve?

3. Would something like durametric catch the fuel pressure?

Thanks for the support.

[Loren]

This is just one of many threads on P1123...

http://www.renntech.org/forums/index.php?showtopic=3834