Mechanics

ENGINE LIGHT OBD CODES 0171/0174/0300

2001 Cadillac Deville

2001 Cadillac DeVille V8-4.6L VIN Y @ 85K miles. Replaced Ho2 sensors, cleaned MAF and replaced air filter. Sensors showed normal wear. Cleared codes and engine runs rough at idle but smooths out at higher RPM. Codes returned. Checked all vacuum lines and EGR all are fine. Do have loud air intake sound near intake manifold? But all looks well.

Ideas and recommendations?
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Rowlandrt
February 23, 2007.




Which 02s were replaced? And was the pcm reset after that, are the codes current?

Tiny
CHEVYII
Feb 23, 2007.
Hmm, let me think about this, the p0171 is bank one lean and you have a random misfire code, im wondering if you have a new part that is bad

Tiny
CHEVYII
Feb 23, 2007.
Replaced the following; Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1
. Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 2
. Heated Oxygen Sensor (HO2S) Replacement Bank 2 Sensor 1

PCM reset and codes are current.

Tiny
Rowlandrt
Feb 23, 2007.
Used after market sensors from Oxygensensors. Com. I had same thought that one of the sensors may be bad? But local mechanic seems to think there may be a air leak in throttle body?

Tiny
Rowlandrt
Feb 23, 2007.
Yeah there is something wrong here, if the ho2s are all known good which at the moment we have no idea, have you checked the fuel pressure yet spec is 41-47 psi

Tiny
CHEVYII
Feb 23, 2007.
Fuel PSI and electrical check fine. MAF seems to be OK but don't want to go there yet.
AD

Tiny
Rowlandrt
Feb 23, 2007.
Meant to use both 0171 & 0174 codes in subject! Just noticed I used 0171 twice.

Tiny
Rowlandrt
Feb 23, 2007.
The throttle body leak really isnt a problem with the caddys, if everything else checks I would fall back to the 02 bank one sensor one, go to gm and get one, when I was at the dealer I would see 02's that were aftermarket bad and reading wrong, you sound like you know what your doing, and youve done some good diagnosis

again my opinion without actually seeing the car suspect b1s1 random misfire lean bank one? Makes sense
if you had a tech 2 scanner you could watch them and see for sure

thanks jim

Tiny
CHEVYII
Feb 23, 2007.
Same difference fuel trim lean bank 2, ho2s related, and I use this loosely most of the time

Tiny
CHEVYII
Feb 23, 2007.
Any way gms procedure for this condition, is check fuel pressure spec, check wiring to h02s, chck for split or laking vaccum hoses, replace h02s related

Tiny
CHEVYII
Feb 23, 2007.

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