Check Engine Light Question
Thread Starter
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Joined: Jun 2003
Posts: 51
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From: Derry, NH
Check Engine Light Question
I have a 99 C4 with 50k miles. Ever since 36k my check engine light comes on weekly! The error code is PO1128. Anyone know how what this means? The dealer does not!!!
Thanks,
Scott
Thanks,
Scott
Drifting
Joined: May 2001
Posts: 2,042
Likes: 3
From: Roseville, CA USA
There is not a fault code P01128 but there is P1128.
P1128 is: Oxygen Sensing Adaptation Area 2 (Cylinders 1 - 3) - Rich Threshold
Usually means: Fuel/air mixture has reached its rich threshold.
Potentially caused by: Intake air leak; fuel pressure too low; fuel pump volume too low; fouled fuel injectors.
Or... potentially a bad oxygen sensor.
P1128 is: Oxygen Sensing Adaptation Area 2 (Cylinders 1 - 3) - Rich Threshold
Usually means: Fuel/air mixture has reached its rich threshold.
Potentially caused by: Intake air leak; fuel pressure too low; fuel pump volume too low; fouled fuel injectors.
Or... potentially a bad oxygen sensor.
Burning Brakes
Joined: May 2001
Posts: 1,163
Likes: 0
From: Washington, DC
Scott,
I think the code spells out what the dealer should be checking for. As for the possibility of an inlet air leak, one typical problem is a cracked oil separator. The oil separator is a plastic cansister that sits on driver side, rear of the engine. It is connected to some vaccum lines from the oil breather in the heads. This cansister can crack or the vaccum lines will split. Either one will cause an inlet vaccum leak and throw a CEL. Have them check for this but if it isn't the problem, they'll have to do step by step elimination of the other potential causes.
Karl
I think the code spells out what the dealer should be checking for. As for the possibility of an inlet air leak, one typical problem is a cracked oil separator. The oil separator is a plastic cansister that sits on driver side, rear of the engine. It is connected to some vaccum lines from the oil breather in the heads. This cansister can crack or the vaccum lines will split. Either one will cause an inlet vaccum leak and throw a CEL. Have them check for this but if it isn't the problem, they'll have to do step by step elimination of the other potential causes.
Karl
Drifting
Joined: May 2001
Posts: 2,042
Likes: 3
From: Roseville, CA USA
Your dealer should be able to check for intake/exhaust leaks, as well as fuel pressure and delivery volume. These are covered in Porsche's Service Manuals and require some Porsche specific tools.
Instructor
Joined: May 2001
Posts: 200
Likes: 0
From: McLean, VA
As long as we're on the subject, I've got a '99 cab with 47K that recently started showing a CEL. The codes are P0410 and P1411, which are "secondary air injection system" for cylinders 1-3 (first code) and cylinders 4-6 (second code).
My mechanic has checked the secondary air pump, and that's working fine.
Has anyone else experienced this, and if so, what was the cause (and fix)?
Thanks for any help,
=Carlos=
My mechanic has checked the secondary air pump, and that's working fine.
Has anyone else experienced this, and if so, what was the cause (and fix)?
Thanks for any help,
=Carlos=
Trending Topics
Pro
Joined: Aug 2001
Posts: 697
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From: New York City, Amagansett, N.Y.
I had a '99 cab (since traded in for an '02) that after I got to about 45k miles had the check engine light come on almost whenever I bought gas but which went out after about a day. I traded the car in before the dealer followed up on the issue.
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