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GM-Frank, ASE Master Certified
Category: Car
Satisfied Customers: 431
Experience:  37 Years Automotive Diagnosis & Repair. Experience with all makes and models..
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I have a 1995 Cadillac Seville STS 4.9L Northstar. I have ...

Customer Question

I have a 1995 Cadillac Seville STS 4.9L Northstar. I have PCM code of P080 which is TP Sensor/Idle learn not complete. It has been determined by a Cadillac Dealer that I have a leaky exhaust valve on cylinder 8. Is there any way to clear this code since the exhaust valve is leaky? Throttle body work has been performed and as far as I know this has all been done correctly. Any way to clear the code?
Submitted: 9 years ago.
Category: Car
Expert:  GM-Frank replied 9 years ago.


Hi Standiamn,

Let's get those codes out of there.

Your Cadillac should have the capability for you to clear the codes.

I"ll send a graphic that explain how to enter the diagnostics of your vehicle.

You may need to play with the system til you get the hang on it, but basically, you enter diagnostics by pressing the Off and Warmer button on your AC Control Center at the "SAME TIME" and hold until you see a digital segement test performed on your display of the drivers information center or cluster area. You are then into the diagnostics mode of the Cadillac. The charts I send you will explain how to scroll through and see all diagnostic trouble codes as well as the option to clear them in each module.

You may need to play a little with the Hi and Lo buttons while you are in diagnostics til you find your way around. Don't worry, you won't hurt anything by doing this. The system will come to a point where is says :"CLEAR CODES" Hold the Hi button for 3 seconds and the code is clear.

All Done, cycle the key off and you are ready to go.

Thanks and I hope this helps you Stan.

Take Care




Customer: replied 9 years ago.
I have done this procedure, but I believe because of the leaky exhaust valve, it immediately comes back when I start car. I have done tp sensor idle learn also and then used clear code procedure. As long as exhaust valve is leaky, i believe that it will continue to come back.
Am I correct.
Expert:  GM-Frank replied 9 years ago.



Let me try to help with this.

An Engine misfire In the engine, if running poorly enough, YES that code could set and not clear or Reset soon after clearing. I found that in writing for you contained below. I don't know how rough your engine is running, but it is possible the inability to clear is tied to poor or unsable Idle quality due to the leaking valve..

If the engine is still running relatively smoothly, then there could be a problem in another system but the code still appears as the P080

Keep in mind that a lot of these systems run on the same circuits and anything can cause anything basically. But the information below will be very important to take into your Cadillac Specialist.

I'd really like to know what a scan tool reading looks like on your vehicle.j I'd need to see the entire picture of all parameters.

I think you'll solve your problem with the information I found for you listed below.

If Code P080 does not change to history following the completion of the TP Sensor/Idle Learn Procedure, this may be due to incorrect or erratic signals from the following sensors:

High electrical loads may disable TP Sensor/Idle Learn. Components that may produce a high electrical load are the headlamps, the rear defogger, high HVAC blower and the cooling fans. If difficulty is encountered learning TP Sensor/Idle values (i.e. Code P080 remains current), turn "OFF" these high electrical loads. Also, it is important to accelerate the engine above 1000 rpm after turning "OFF" the above components because the PCM will think it is still under a high electrical load until it checks the system again (when engine rpm exceeds 1000 rpm). Furthermore, since the cooling fans cannot be manually controlled, engine coolant temperature must be below 105°C and A/C refrigerant temperature must be below 51°C in order to turn "OFF" the high speed cooling fans and their high electrical load.

Code P080 may also remain current if the idle is rough or unstable. Correct problems with these sensor's signals or the idle before attempting to perform the TP Sensor/Idle Learn.

Hope this is what you are looking for.

Keep me posted


GM-Frank and 5 other Car Specialists are ready to help you
Expert:  GM-Frank replied 9 years ago.


Thank You very much for the extra. It is appreciated.