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Diagnostic code po503 i have replaced speed sensor and two oxygen sensors
1999 Cadillac DeVille

Diagnostic code PO503 I have replaced speed sensor and two oxygen sensors

(1999 Cadillac DeVille)
PO503 Could you give me an estimate to replace the wiring harness. Could be a short circuit maybe. Thanks.
1 answer & 2 comments
Popular Answer
on December 04, 2010
The P0503 code is for the speed sensor, so I'm not sure why the O2 sensors were replaced. Not sure about the wiring harness cost, but I would pay a qualified tech to diagnose this issue to determine what is wrong. I wouldn't replace the wiring harness before having it looked at, otherwise you risk wasting more cash.
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on December 06, 2010
I have taken it to a GM authorized dealer who kept it two days and still could not tell me why the light keeps coming on to the tune of $700. for this one trip. Thanks for your help.
I took my car to another GM dealer in Nashville and they wanted to replace the transmission in my car. The transmission does not seem to be a problem. Do you have any other suggestions



































General Diagnosis
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on December 04, 2010
The P0503 code is for the speed sensor, so I'm not sure why the O2 sensors were replaced. Not sure about the wiring harness cost, but I would pay a qualified tech to diagnose this issue to determine what is wrong. I wouldn't replace the wiring harness before having it looked at, otherwise you risk wasting more cash.
Sign in to reply
on December 06, 2010
I have taken it to a GM authorized dealer who kept it two days and still could not tell me why the light keeps coming on to the tune of $700. for this one trip. Thanks for your help.
I took my car to another GM dealer in Nashville and they wanted to replace the transmission in my car. The transmission does not seem to be a problem. Do you have any other suggestions



































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