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I have a 2002 911 Turbo that I acquired 60 days ago and on Monday the check engine light came on. The car passed smog when purchased and now has 50k miles. I was near a Dealer and they read the code but since it was closing time they did not really go over the print out they gave me. The Service person at the Dealer noticed that the inside of the exhaust tips were white, both of them, indicating lean combustion.

I have a 13 page listing and there are 5 Faults. However, these Faults occurred at Operating Hour 1450 and the car is now at Hour 1650 (given in the POSIP (?) section of the listing).

The Faults are: P0300 Misfire detection [P0306 cylinder 6; P0304 cylinder 4; P0305 cylinder 5] and P0040 Oxygen sensors in front of cat. conv. switched.

So are these are old Faults which happened 200 hours ago (~6,000 miles ago) and are no longer a problem?

The first four Faults listed above give the "last state:" Operating Hours as 0.1 larger than in the "1st state".

The Fault P0040 has the same 1st state Operating Hour of 1450 but only blanks for the last state entries. Is this still a problem?

The output reads:

P0040 Oxygen sensors in front of cat.

conv. switched

intermittent

not present

Lamp off

1st state: last state:

Signal implausible Signal implausible

Frequency: 1

Clear Counter 10

Fault time: 0 s

Check Engine on: Driving Cycle 001

Check Engine off: Driving Cycle 003

Lambda value is 0.01 and 0.00 for bank 1 and 2.

ECTS: 83 in 1st state

Operat. hours counter: 1455.0

OBD II code P0040

Under the Freeze Frame information: O2 sensing is control active, both banks.

Load: 9.4 %

ECTS: 82 deg C

Oxygen sensing: 22.6 %

O2 sensing adaption: -1.6 % (negative % ok ?)

O2 sensing, bank 2: -20.4 %

O2 sen. adap., bank2 -3.2 %

RPM: 3080

Speed: 75 km/h

Fault entered by: On-board diagnosis

My wild guess is that if it is running lean then there could be a problem with the fuel supply: fuel pump, fuel filter and/or ?

Should that have thrown a Fault?

From the renntech Forum there was: motor cuts out after gas fill-up: there was a check valve on the vapor recovery line that was getting stuck open because a carbon canister on the fuel recovery system started to disintegrate (the carbon particles sat in the seats of the check valve and would not let it seat (close) properly) - reasonably easy fix.

Currently, my choices are:

1) take it back to the Dealer and let them try at it,

2) take it to an independent shop which does have cheaper labor rates and a history of racing Porsches in the 1990's, or

3) start replacing things at home.

UPDATE (May 14): I did Option 2, took it to an independent shop.

The spring connecting the dual-mass flywheel is allowing too much flex. This affects the timing and the confused computer sets the timing to zero (and this leads to a misfire?). Will post again after flywheel is replaced.

UPDATE (May 23): Replacing the Dual-Mass flywheel cured the problem. Check Engine light only came on when driving as the spring in the flywheel only affected the timing when under the load of moving on the road. Installed a single mass flywheel and had to also replace the O2 sensor before the cat on the right side in order to get the computer to reset for the light weight flywheel.

The exhaust tips are no longer the white color, they are now black and so it may have been running lean due to the timing confusion.

(The engine operating hours are at 1450 and we do not know why the POSIP (Porsche Side Impact Protection) has 200 more operating hours.)

Edited by BillTurbo
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  • Admin

P0040 Oxygen sensor ahead of catalytic converter – signal implausible (only Turbo)

Possible fault cause

- Oxygen sensors ahead of catalytic converter exchanged

- Line polarity reversal in wiring harness

- Simultaneous occurrence of leaking fuel injector on the one bank and leaking intake distributor on the other bank

Diagnosis detects oxygen sensor - regulators running contrary to the adaptation limitation.

- For example: The regulator for bank 1 detects an excessively rich mixture and wants to make it leaner. At the same time, the regulator on bank 2 detects an excessively lean mixture and wants to make it richer. If the oxygen sensors or their signal wires have been exchanged, the detected bank 1 continues to make the mixture richer and bank 2 continues to make the mixture leaner. Only when both oxygen sensors remain on the opposing stops for a certain period of time will this fault be recorded.

1. Check if the oxygen sensors were exchanged due to incorrect installation of or tampering with the wiring harness.

2. Disconnect oxygen sensor plug connection ahead of catalytic converter, bank 1

- Visual inspection

- Remove control module connector B

Check following wiring for continuity:

- Oxygen sensor connector ahead of catalytic converter pin 1 and DME control module connector B pin 15

- Oxygen sensor connector ahead of catalytic converter pin 5 and DME control module connector B pin 9

- Oxygen sensor connector ahead of catalytic converter pin 2 and DME control module connector B pin 2

- Oxygen sensor connector ahead of catalytic converter pin 6 and DME control module connector B pin 5

All should be <2 ohms.

3. Disconnect oxygen sensor plug connection ahead of catalytic converter, bank 2

- Visual inspection

Check following wiring for continuity:

- Oxygen sensor connector ahead of catalytic converter pin 1 and DME control module connector B pin 16

- Oxygen sensor connector ahead of catalytic converter pin 5 and DME control module connector B pin 10

- Oxygen sensor connector ahead of catalytic converter pin 2 and DME control module connector B pin 6

- Oxygen sensor connector ahead of catalytic converter pin 6 and DME control module connector B pin 24

All should be <2 ohms.

4. After reading out the oxygen sensor values, search for a leaking fuel injector on the bank with the lean threshold and search for false air on the bank with the rich threshold.

Since you only have misfires on bank 2 (cyl 4, 5, 6) it would be interesting to see the O2 sensor readings compares between bank 1 and bank 2.

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Bill: Glad to see you came over to RennTech to solicit some info from Loren. I saw your question posed on another forum...most all of his diagnosis comes from documentary sources from Porsche and the PIWIS or PST2 readouts. His information doesn't deal with "feels like" sorts of responses...but come from authoritative sources.....not shadetree replies.

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  • 3 months later...

Wow. I have this exact CEL problem/codes. The CEL usually flashes for a few seconds around 3000 rpm (steady throttle) then stops. I tried to find the source some months ago; no one fully figured it out. I had an 02 sensor replaced (ahead of catalytic), but the CEL soon returned. I then decided to ignore it since it runs fine. Bill, has the CEL come back since the flywheel replacement? Is there a way to fix the problem without replacing the flywheel? Any help is greatly appreciated.

Steve

I have a 2002 911 Turbo that I acquired 60 days ago and on Monday the check engine light came on. The car passed smog when purchased and now has 50k miles. I was near a Dealer and they read the code but since it was closing time they did not really go over the print out they gave me. The Service person at the Dealer noticed that the inside of the exhaust tips were white, both of them, indicating lean combustion.

I have a 13 page listing and there are 5 Faults. However, these Faults occurred at Operating Hour 1450 and the car is now at Hour 1650 (given in the POSIP (?) section of the listing).

The Faults are: P0300 Misfire detection [P0306 cylinder 6; P0304 cylinder 4; P0305 cylinder 5] and P0040 Oxygen sensors in front of cat. conv. switched.

So are these are old Faults which happened 200 hours ago (~6,000 miles ago) and are no longer a problem?

The first four Faults listed above give the "last state:" Operating Hours as 0.1 larger than in the "1st state".

The Fault P0040 has the same 1st state Operating Hour of 1450 but only blanks for the last state entries. Is this still a problem?

The output reads:

P0040 Oxygen sensors in front of cat.

conv. switched

intermittent

not present

Lamp off

1st state: last state:

Signal implausible Signal implausible

Frequency: 1

Clear Counter 10

Fault time: 0 s

Check Engine on: Driving Cycle 001

Check Engine off: Driving Cycle 003

Lambda value is 0.01 and 0.00 for bank 1 and 2.

ECTS: 83 in 1st state

Operat. hours counter: 1455.0

OBD II code P0040

Under the Freeze Frame information: O2 sensing is control active, both banks.

Load: 9.4 %

ECTS: 82 deg C

Oxygen sensing: 22.6 %

O2 sensing adaption: -1.6 % (negative % ok ?)

O2 sensing, bank 2: -20.4 %

O2 sen. adap., bank2 -3.2 %

RPM: 3080

Speed: 75 km/h

Fault entered by: On-board diagnosis

My wild guess is that if it is running lean then there could be a problem with the fuel supply: fuel pump, fuel filter and/or ?

Should that have thrown a Fault?

From the renntech Forum there was: motor cuts out after gas fill-up: there was a check valve on the vapor recovery line that was getting stuck open because a carbon canister on the fuel recovery system started to disintegrate (the carbon particles sat in the seats of the check valve and would not let it seat (close) properly) - reasonably easy fix.

Currently, my choices are:

1) take it back to the Dealer and let them try at it,

2) take it to an independent shop which does have cheaper labor rates and a history of racing Porsches in the 1990's, or

3) start replacing things at home.

UPDATE (May 14): I did Option 2, took it to an independent shop.

The spring connecting the dual-mass flywheel is allowing too much flex. This affects the timing and the confused computer sets the timing to zero (and this leads to a misfire?). Will post again after flywheel is replaced.

UPDATE (May 23): Replacing the Dual-Mass flywheel cured the problem. Check Engine light only came on when driving as the spring in the flywheel only affected the timing when under the load of moving on the road. Installed a single mass flywheel and had to also replace the O2 sensor before the cat on the right side in order to get the computer to reset for the light weight flywheel.

The exhaust tips are no longer the white color, they are now black and so it may have been running lean due to the timing confusion.

(The engine operating hours are at 1450 and we do not know why the POSIP (Porsche Side Impact Protection) has 200 more operating hours.)

Edited by riley6
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  • 2 months later...
Loren,

Any advice?

Steve

Follow the troubleshooting tree I posted above - IF your faults are exactly the same.

Loren,

Your troubleshooting tree does not involve replacement of flywheel, So i am assuming its okay to use stock flywheel when upgrading clutch. The flywheel shouldn't cause these issues?

I have the same exact faults , it occurred when we put in a clutch and upgraded the injectors.

Thanks , i will have my mechanic check the 02 sensors and injectors again.

Edited by v996tt
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  • 2 years later...

Up date Dec 5, 2011 The check engine light did not come back on since replacing the dual mass flywheel with the single mass flywheel.

The motor did break recently -- the Sprocket wheel that drives the right camshafts broke at its key way (and all the valves are bent on the right side).

The single mass flywheel did give a lot of chatter and in hindsight the chatter increased in the weeks before motor broke.

Does anyone have reasons to suspect that the lack of vibration damping with the single mass flywheel caused the Sprocket wheel failure?

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