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sts-v
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Discussion Starter #1
Just got a CEL - P2138 on my 2007 STSV. Apparently the code is related to the "Throttle/Pedal Position Sensor/Switch "D"/"E" Voltage Correlation".

I had been noticing some lag in accel. pedal response and then reduced engine power message display. I also noticed it happens during heavy wash but now it’s in “limp mode” continually.
I looked around the internet/threads and I found this mentioned by Chris “ RippyPartsDept”

The throttle body has a sensor built into it and the accel. pedal also has a sensor built into it
the two sensors are checked against each other by a module (probably the ecm) to make sure that the commanded throttle position (by the pedal sensor) matches the monitored throttle position (by the TPS). So that would mean that the two sensors are not matching up (for whatever reason)
it could be that either the APP or the TPS is faulty and that's why they're not matching up
and that would require you to change out either the pedal or the throttle body.
BUT
I also saw a bulletin that mentions this code intermittently setting off the reduced engine power message due to a problem with the connection between instrument panel harness and the body harness
Condition
o Some customers may comment on an intermittent malfunction indicator lamp (MIL) being Illuminated with a message or an indicator that displays Reduced Engine Power.
o The technician may observe on a scan tool DTC P2138 – Accelerator Pedal Position (APP) Sensor 1-2 Correlation set as Current or in History.
Cause
o This condition may be caused by water intrusion into the instrument panel (IP) to body harness connector, which carries the APP sensor signals to the ECM/PCM. This water intrusion results in a voltage difference between APP Sensor 1 and APP Sensor 2 that exceeds a predetermined value for more than a calibrated period of time, setting P2138.
Next line of action should probably be to inspect that IP to body harness connector for any corrosion and repair it if you do find any.

Now can anyone tell me where this connector which relates to APP sensor / TPS is? Pictures would be highly appreciated.
Thanks
 

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sts-v
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60 Posts
Discussion Starter #3
Thanks Timmy for your response. Now do I need to lift the supercharger to reach to that connector?
If I managed to get the connector apart and let it dry and put some dielectric grease in it would it help to some extent? Or its failed Throttle body needs to be replaced and how difficult to take it apart since its behind the supercharger.
 

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sts-v
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Discussion Starter #5
Thanks Tim. Is there any other connector/connection I should also check before start replacing parts?
 
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