996 CEL Codes ....

[stutzchris]

Okay. Been driving My2001 a bit now and CEL came on second time ... Reset when I changed aging battery a month and a half ago. I am suspecting after market exhaust has a bit to do with it. Cleared a while back and just came back after hammering a bit.

Durametrics Codes:

P1128

PORSCHE 360-oxygen sensor adaptation idle range bank 1

P1130

PORSCHE 361-oxygen sensor adaptation idle range bank 2

P0139

PORSCHE 17-Sensor aged behind can conv. cylinder (1-3)

So ... oh great and wonderous knowers of all things Porsche ... give me some input and cures for these, Please! DIY's or Shop ...

Thanks in advance ...

[Ahsai]

Can you describe a bit about the aftermarket exhaust part? Any exhaust leak? Also check intake leak like at air filler tube, AOS, intake manifold, etc.?

What are the TRA and FRA values on both banks? What are the O2 sensor readings pe-cat and post-cat on both banks look like?

Also, what's the MAF reading at idle fully warmed up with a/c off.

Edited February 18, 2014 by Ahsai

[Ahsai]

FYI http://www.renntech.org/forums/topic/32802-error-codes-p1128-and-p1130/

[stutzchris]

Thanks Ahsai. I will order a MAF today ... Start there ...

[Silver_TT]

The P0139 indicates you might need a new post-cat o2 sensor

[Ahsai]

Thanks Ahsai. I will order a MAF today ... Start there ...

Actually if you read what Loren said in that link, MAF is only one of the possibilities. The other ones are air leak, low fuel pressure, etc hence my questions to you. I do hope that the MAF will solve it for you though but without any diagnostic you will be taking a chance.

Edited February 19, 2014 by Ahsai

[stutzchris]

I will get readings and post them in the next day or so .... Thanks ....

Than aftermarket exhaust has no visible branding. It is a Cat back chrome system.

Edited February 19, 2014 by stutzchris

[stutzchris]

Okay Here are the numbers/values

Oil Temp 82C & Engine Temp 88.5C

Idle 780 ish

MAF=1.40 (values change as revs increase)

Bank 1

RKAT=4.22

FRA =0.99%

Bank 2

RKAT=4.50

FRA =0.99%

Edited February 19, 2014 by stutzchris

[Ahsai]

Okay Here are the numbers/values

Oil Temp 82C & Engine Temp 88.5C

Idle 780 ish

MAF=1.40

Bank 1

RKAT=4.22

FRA =0.99%

Bank 2

RKAT=4.50

FRA =0.99%

Looks like air leak at intake since it adds more fuel when idling (RKAT) but does not add/subtract much when at load (FRA) where vacuum leak has little effect. MAF reading looks fine.

Can you read the MAF reading in kg/hr instead of voltage? It should be ~17kg/hr @idle and ~50-80kg/hr @3000 rpm.

Do you feel any leak where your cat back system is connected to the cats? Can you remove your oil filler cap with ease but with some suction?

Also agree with Silver you may need a post-cat sensor on bank1 (P0139).

Edited February 19, 2014 by Ahsai

[Ahsai]

Explanation of the fuel trim numbers FYI http://www.callasrennsport.com/porsche-986-996-987-997-fuel-trim-information/

[stutzchris]

I did some exploring around the the Air intake piping and found the post MAF clamp was very loose. I tightened that down. The clamp at the throttle body was fine. I have driven twice since clearing the codes and no CEL yet. I ordered an 02 Sensor to replace the aging post cat sensor Will monitor and update.

[Ahsai]

Good progress and thanks for the update.

[george996]

i agree with ahsai, looks like a leak. check your oil filler cap as well. Also, idle should be about 700 rpm and the fact that you are at 780 rpm is another indication of a leak. MAF should be about 1.25 volts with about 17 kg/hr at 700 rpm. Make sure you are reading the mas flow measured by the MAF sensor and not the total mass flow which is calculated.

did you change the cats? if so make sure the o2 sensors are not switched (upstream vs. downstream).

Edited February 28, 2014 by george996

[stutzchris]

Replaced both down stream O2 Sensors ... Those codes are gone ... MAF is reading properly at 1.25 and 17kg/hr the other codes have not returned since replacing o2 Sensors ...

[Ahsai]

Replaced both down stream O2 Sensors ... Those codes are gone ... MAF is reading properly at 1.25 and 17kg/hr the other codes have not returned since replacing o2 Sensors ...

All right! May take some driving cycles to be 100% sure though to let the O2 sensor tests run and complete. I like your odds though based on your previous codes.

[george996]

Replaced both down stream O2 Sensors ... Those codes are gone ... MAF is reading properly at 1.25 and 17kg/hr the other codes have not returned since replacing o2 Sensors ...

did you get any faults for the duration after you tightened the clamps but before you replaced the down stream sensors?

[stutzchris]

Since tightening the clamp these two codes have not returned.

P1128

PORSCHE 360-oxygen sensor adaptation idle range bank 1

P1130

PORSCHE 361-oxygen sensor adaptation idle range bank 2

I was getting a CEL every 150 to 175 km for the O2 Sensors after that ... I replaces both sensors since i was removing the rear bumper to gain easy access to the downstream sensors. My logic is if one is going then the other can't be far behind. I assume they have not been replaced before. Unfortunately, the spring type warm up we had has left us now and I have not taken the car out since changing the sensors over. I will update when I have driven it a few hundred km.

[Loren]

Since tightening the clamp these two codes have not returned.

P1128

PORSCHE 360-oxygen sensor adaptation idle range bank 1

P1130

PORSCHE 361-oxygen sensor adaptation idle range bank 2

I was getting a CEL every 150 to 175 km for the O2 Sensors after that ... I replaces both sensors since i was removing the rear bumper to gain easy access to the downstream sensors. My logic is if one is going then the other can't be far behind. I assume they have not been replaced before. Unfortunately, the spring type warm up we had has left us now and I have not taken the car out since changing the sensors over. I will update when I have driven it a few hundred km.

Sounds like you have an intake air leak.

Best do some testing with a smoke machine.

[stutzchris]

Thanks Loren ... I was directed to that and found the source of the leak. The post MAF clamp was loose. I tightened it down. Those codes related to the leak are gone. I was answering george996's question.

[george996]

stutzchris, so P0139 returned after tightening the clamps?

I was wondering if P1128 & 30 faultes ever returned since, according to the 7.2 DME technical manual , an aging problem of the down stream o2 sensor (i.e. voltage remians below or above 0.6 volts for 80 seconds) will change the mixture either more rich or lean. I thought perhaps that P0139 was the root cause for all your CEL's. However it sounds like you had two problems. On the otherhand, when your CEL went on all three codes were present simultaneously and an air leak would not casue P0139. So perhaps P0139 was the root.

Good information. thanks for the feedback.

[stutzchris]

I have been able to put some k's in this week. After 800 km of driving the CEL returned with the P1130 code. This is the only code. I pulled the MAF and cleaned it very well. It seems odd the code bounces back and forth from 1 bank to the other. The O2 sensor code is gone. Now I have a new set of Pre Cat O2 sensors as well. Should I replace those as well? Could the pre cat sensors be aging and causing this?

I understand the P1128 & P1130 codes are "air leaks" but would they not be consistent to one bank or the other or both?

The car runs fine ... Did 400 km trip the fuel consumption was amazing even running 130 kph average.

[Loren]

Not likely an O2 sensor unless you have other codes.

I understand the P1128 & P1130 codes are "air leaks" but would they not be consistent to one bank or the other or both?

That would depend on where the air leak is.

[stutzchris]

Okay ... guess the smoke test it is ... is the a progression of where to start smoke test?

[DBJoe996]

FYI - I went through several iterations of cleaning the MAF sensor and many miles. The CEL just kept coming back. I finally just replaced it. I figured it was 15 years old (my 99 C2 w/129,000+ miles) and needed replacement. I was right.

Edited April 9, 2014 by DBJoe996

[Ahsai]

Ah, bummer.

What are your current RKAT and FRA vaules on BOTH banks? That will tell us if they are trully asymmetrical or just that one bank is a little worse than the other so it trips the code for that bank.

O2 sensors have their own codes so most likely they are fine. You can select precat O2 voltage and post cat O2 voltage (and no other actual values) and plot them both in durametric when idling and at speed. At idle the precat voltage should swing between 0.2v to 0.8v about once a second while the postcat should be steady at ~0.6-0.7v most of the time. When you snap the throttle, the postcat will go high instantly and drop back to 0v once you release the throttle, then slowly builds itself up to ~0.7v again. At speed, same as above except the precat will swing faster.