A while back, if I drove my 2001 996 Carrera rather spirited, two lights would illuminate on my dashboard: PSM Off and ABS. Many of you on this board recommended cleaning the MAF and replace it if cleaning didn’t help. So, I replaced the MAF and that fixed the problem. The car ran noticeably better (and I thought it ran great before that).

Now, I have a new (potentially related) problem. After I replaced the MAF, I cleared these codes:
P0507 - Idle Control at Startup
P1128 - Oxygen Sensing Adaptation, Idle Range, Bank 1

A couple of people suggested replacing the Fuel Pump Relay. I forget the reasoning, but it made sense. It’s also cheap (like $22) and easy, so I didn’t mind trying it. I had to order it though, the dealer was out. However, before it arrived, I took a weekend road trip (San Jose to LA, about six hours on the road). Half way there, the CEL illuminated. I had my OBD scanner with me, so I ran it and found these errors:
P0507 - Idle Control at Startup
P1128 - Oxygen Sensing Adaptation, Idle Range, Bank 1
P1130 - Oxygen Sensing Adaptation, Idle Range, Bank 2

I cleared those errors as I really didn’t want to look at the CEL my entire trip. That helped, but two days later and half way home, the CEL came on again. Once I got home, I scanned the car again and got these errors:
P0430 - Cat Conv. Efficiency, Bank 2
P0420 - Cat Conv. Efficiency, Bank 1
P1128 - Oxygen Sensing Adaptation, Idle Range, Bank 1
P1130 - Oxygen Sensing Adaptation, Idle Range, Bank 2

I picked up the Fuel Pump Relay and replaced it, cleared the codes, and that’s currently where I’m at. Not sure if the CEL will come back on or not as I just replaced it and drove around the block afterwards.

The car has been running and driving just fine, no strange sounds, smells, and no rough idling either. The CEL came on at normal highway speeds (75ish), not during idling, slow speeds, or even performance driving.

I’m wondering if anyone has any tips/advice what to do next if the Fuel Pump Relay doesn’t resolve the issue. Am I looking at Oxygen Sensors… or something else?

 

Have you recently done anything to contaminate the Cats? For example huge oil ingestion,AOS, High ZDDP oil, Excessively rich mixture/overfuelling, Aftermarket "Tune",problems with Fuel Pressure regulator.
Odd that both cats deteriorate simultaneously. Expensive also.Hence the questions.

 

Nope, the car is stock, other than the IMS fix performed by Flat Six Innovations well before I ever owned it. The person I bought it from only used the Joe Gibbs oil in the car that LN Engineering recommends after the IMS solution has been installed.

 

In that case it is Durametric time !
Or PIWIS.

 

0507, 1128, 1130 all point to intake air leak. Common places...intake boot to throttle body not sealing, oil filler tube cracked at some out of sight places.

 

I wonder if when you replaced the MAF, something was dislodged or is loose?

 

I don't think so, but I will double check all that and ensure everything is fitted the way it should be.