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986 Boxster error codes p1123 p1125

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I am experiencing CEL codes P1123 and P1125 on my 1999 986 2.5. 54k miles Third owner.  What is this telling me?  O2 sensors or MAF???

When I run a test on the O2 sensors they pass? Any assistance will be greatly appreciated.

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P1123 Oxygen Sensing Adaptation Area 1 (Cylinders 1 . 3) - Lean Threshold
P1125 Oxygen Sensing Adaptation Area 1 (Cylinders 4 • 6) - Lean Threshold


This is telling you your fuel mixture is too rich. So rich the DMEcan not compensate for it.


Possible causes:

- Fuel pressure too high.
- Fuel injector leaking.
- EVAP canister purge valve open.


The most common cause we have seen here is the canister purge valve is open.


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Do you have a picture of location of the evap canister control valve?


The Bentley Boxster manual states that it's located on the left side of the motor under the exhaust manifold?


101 projects for the Boxster by Wayne Dempsy does not address this issue.





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The PET and 986 WSM do cover completely the evap canister control valve.  You should get a set.  More comprehensive and covers your car bumper to bumper.... 


PM me.    A little just to get you started....


357 Oxygen Sensing Adaptation, Upper Load Range,
Bank 1 - Below Limit
Diagnosis conditions
• Oxygen sensing system active
• Time elapsed after engine start-up: 250 to 350 seconds (USA)
• Time elapsed after engine start-up: 302 to 402 seconds (RoW)
• Engine temperature greater than 60 °C
• Mass air flow greater than 180 kg/h
Possible fault cause
♦ Incorrect signal from MAF sensor
♦ Fuel pressure too high
♦ Fuel injector leaking
♦ EVAP canister purge valve open

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Thanks for the help on p1123 and p1125 CEL codes.


The evap canister purge valve was the culprit. 

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