P1128 Check Engine Light

[rcg412]

Have a '01 911 Carrera 2 (49K Miles). Check engine light came on Friday, got it checked and reset at Autozone, ODB Code: P1128. About 5 days later, it came on again... taking it to the dealer tomorrow.

Car runs perfectly, although idle wavers very slightly at rest. Any thoughts? Thinking MAF?

I have the Autosource extended warranty, so hoping it is all covered. Thanks, Ross (Newbie)

[trauh]

If you do a search for P1128 you'll find lots of information. I had the same problem and after a long process finally resolved it by tightening the throttle air intake bolts.

[rcg412]

Just got the car back from the dealer - air filter manifold was not tightly shut... Ross

[Eric]

Have a '01 911 Carrera 2 (49K Miles).  Check engine light came on Friday, got it checked and reset at Autozone, ODB Code: P1128.  About 5 days later, it came on again... taking it to the dealer tomorrow.

Car runs perfectly, although idle wavers very slightly at rest.  Any thoughts?  Thinking MAF? 

I have the Autosource extended warranty, so hoping it is all covered.  Thanks, Ross (Newbie)

<{POST_SNAPBACK}>

A good chance it's the fuel cap. Just tighten it, or it may need replacing.

Eric

[tt2001]

Just got the car back from the dealer - air filter manifold was not tightly shut...  Ross

<{POST_SNAPBACK}>

Hi trauh, I have the simillar problem and want to know where is the throttle air intake bolts locate?

Thanks,

Tt

[trauh]

My mechanic did the work so I can't guide you specifically. But I am sure that Loren or another member can...

[rcg412]

Have a '01 911 Carrera 2 (49K Miles).  Check engine light came on Friday, got it checked and reset at Autozone, ODB Code: P1128.  About 5 days later, it came on again... taking it to the dealer tomorrow.

Car runs perfectly, although idle wavers very slightly at rest.   Any thoughts?  Thinking MAF? 

I have the Autosource extended warranty, so hoping it is all covered.  Thanks, Ross (Newbie)

<{POST_SNAPBACK}>

A good chance it's the fuel cap. Just tighten it, or it may need replacing.

Eric

<{POST_SNAPBACK}>

Eric - The light came on again.... after about 700 miles, we filled up and ~15 miles away CEL came back on. Car rides perfectly, very confusing... Going to dealer on Friday, they said it was fine to drive.

[Loren]

Gas cap o-ring?

[tt2001]

Tight the throttle air intake bolt work for me, the CEL light not back on so far. Thank you for your hint Trauh. :drive:

[trauh]

You are welcome. And I hope it stays off!

[gcp]

Today I also zeroed the CEL light with an AutoZone OBDII. The code reading was P1128 which, according to AutoZone computers, means "Upstream Heated O2 Sensors Swapped"....whatever that means :soapbox:

I had the CEL light come on a week ago, after I purchased my 2K Carrera, and was told by a specialist that the O2 sensor on the cat input was bad so he replaced it at the tune of $385, only for the light to come back on after a couple of hundred miles worth of driving. I am new to this car so I can't offer any advice, just my own symptoms to add to your list.

BTW, I am glad to be part of your group and look forward to contributing if/when I get more knowledgeable on 996s.

Thanks,

[Loren]

Today I also zeroed the CEL light with an AutoZone OBDII. The code reading was P1128 which, according to AutoZone computers, means "Upstream Heated O2 Sensors Swapped"....whatever that means  :soapbox:

I had the CEL light come on a week ago, after I purchased my 2K Carrera, and was told by a specialist that the O2 sensor on the cat input was bad so he replaced it at the tune of $385, only for the light to come back on after a couple of hundred miles worth of driving. I am new to this car so I can't offer any advice, just my own symptoms to add to your list.

BTW, I am glad to be part of your group and look forward to contributing if/when I get more knowledgeable on 996s.

Thanks,

What year and how many miles please?

[gcp]

Loren, my car is a 2000 with 39,200 miles, now. I bought it Monday week ago and the last 1,000 miles happened this past weekend , taking it home :drive:

So far it's proven a great car, it runs perfectly except for this minor CEL .

Thanks,

gcp

Edited September 26, 2005 by gcp

[Loren]

P1128 Oxygen Sensing Adaptation Area 2 (Cylinders 1 - 3) - Rich Threshold

This means that the fuel mixture on the cylinder 1-3 side is too lean - that is, the DME can not increase richness enough to compensate for the lean condition.

The most obvious cause of this is an intake leak on that side and or bad readings from the MAF. Beyond the air leak it could be a bad seal on the gas cap or oil cap, a bad MAF, a bad oil separator, etc. You need more info to fully diagnose the fault. You should find a shop with a Porsche PST2 or PIWIS tester so they can confirm whether the MAF is seeing erratic air pressures.

[gcp]

Thanks for your input Loren. The dealer is 79 miles one way from me and I will get down there eventually but in the mean time how do I go about finding, removing, cleaning and reinstalling the MAF? Any specific direction on doing this job pinned here or elsewhere?

Thanks,

gcp

[Loren]

I wouldn't start with the MAF. I would start by checking the seals on the gas cap and oil cap. And, make sure they are properly seated. They I would start looking and listening for air leaks - checking the hoses. Then I might clean the MAF with electronic contact cleaner. I wouldn't mess with a $400 part unless I am sure that is the problem and ready to replace it - IMHO of course.

[gcp]

Loren, I checked all of the above yesterday and it all seems to be in order, that's why I was thinking of tackling the MAF.

Thanks,

gcp

Edited September 27, 2005 by gcp

[trauh]

Try spraying the throttle air intake with carburetor cleaner while the engine is running to see if there is an air leak. Several of us have had P1128 CELs that were correctly by tightening that. Spraying carburetor cleaner was how I tracked it down on my vehicle. Good luck.

[gcp]

Will do, thanks trauh!

[gcp]

I now suspect that the CEL may be because of my leaking expansion tank...and I am just guessing here but lets solve the obvious first.

The mechanic said this code means MAF problems. So cleaning the part may prove worthwhile after all :thumbup:

Thanks,

gcp

Edited September 28, 2005 by gcp

[rcg412]

I now suspect that the CEL may be because of my leaking expansion tank...and I am just guessing here but lets solve the obvious first.

The mechanic said this code means MAF problems. So cleaning the part may prove worthwhile after all  :thumbup:

Thanks,

gcp

<{POST_SNAPBACK}>

Did you ever get your problem fixed? My CEL came back on... Not sure of the error code yet. Quite frustrating.

[gcp]

Nop, no real resolution to the CEL problem as of yet. But since last Sunday my light has stayed off :clapping: ...Of course I'm not holding my breath!

gcp

Edited September 29, 2005 by gcp

[rcg412]

Nop, no real resolution to the CEL problem as of yet. But since last Sunday my light has stayed off :clapping: ...Of course I'm not holding my breath!

gcp

<{POST_SNAPBACK}>

Mine seems to come on every two weeks, after ~750 miles. The fix is always something dumb, like loose vacuum hose or oil cap filler. Car rides fantastic.

[tt2001]

After a long process - changed MAF, Speak plugs, Speak boots, O2 sensors and ...etc... problem seems resolved by trauh's way -

Tightening the throttle air intake bolts. CEL not back for almost one month 1000mils. it must some please has vacuum leak. And now the car seems more smooth and has better gas mileage.

[trauh]

I spent 3 months on the trail of my P1128 before we found the air throttle intake leak. And I've put over 1,000 miles on it without recurrence, where I used to get the CEL every 100-200 miles. Since we discovered the fix, I've seen 3 or 4 others who had the same problem and fix. Seems like a design flaw that it can loosen up, but its easy to check, so I suggest giving it a try.