Po503
 

Car does not idle very good. Autozone scanned it and PO503 came up as well as PO153. I'm guessing I need a couple new O2 sensors but I'm not sure what the PO503 is all about. Sorry but search still doesn't work. Thanks for any help.

DTC P0503 Vehicle Speed Sensor (VSS) Circuit Intermittent

P0153 -- slow response bank 2 sensor 1

Most likely a lazy O2 sensor... if you still have your rear post cat O2 sensors you can try those... they're the same as fronts on F-Bodies

the 503 I'm not sure on... when did the SES start? after any mods ? (especially around the tailshaft of the transmission?)

The SES came on after mods. I did the H/C swap and the SES light came on with several codes. I then had the car dynotuned and had the downstream O2 codes deleted since I'm running ORY. I also had the EGR deleted. Shortly after having the car dynotuned the SES light came on and PO503 and PO153 is what came up on the scanner. Is bank 2 sensor 1 on the driver side or passenger side? When I had the PCM scanned at autozone the scanner said something about idle for PO503. The car does not idle very good. I usually have to put my foot on the pedal a little to keep it running. I don't think the idle problem is related to the cam.

the P0153 code will put you into open loop operation which can explain the poor idle

P0503 i got off http://www.obdii.com/codes.asp (sticky on top)

503 is the VSS which I believe is at the tailshaft of the trans

Bank 1 = Driver Side
Bank 2 = Passengar Side
Sensor 1 = pre cat
Sensor 2 = post cat