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1995 gmc k1500 code 32 and high nox

Joeyblaze

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Joeyblaze Enthusiast

Joeyblaze

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I have a 1995 GMC k1500 4x4 with the 5.7L TBI engine in it. I just bought the truck and as it is about 24 years old, it only needs to pass one more emisions test before It is grandfathered and therefore immune to e-checks (I live in northern Ohio) and also before I can get plates for it. The problem is, I've failed e check 3 times. A code 32 pops up every time I test it (on my own with a reader) and when I got the emissions test, high nox is the reason it fails. This would make sense, as code 32 is an egr error, and the egr being faulty would definitely trigger high nox, however:

The egr valve has been replaced (yes, a negative one) 

The egr vacuum solenoid has been replaced 

Map sensor replaced 

Spark plugs, cap, rotor, wires. Replaced

Even went as far as to replace the oxygen sensor.  

There doesn't seem to be any vacuum leaks and every test I've done on any part of the egr system points to it all running correctly. 

 

The kicker is: the truck runs great! No loss in power. Idles great. Super clean and well kept truck. 

 

Notes : it does have a Flowmaster super 10 dual exhaust on it, but it isn't a true dual as only one pipe comes from the catalytic into the exhaust, Then two come out. 

 

Also, high nox seems to be caused by high engine Temps, however, my engine temp on my dash shows that it never gets above about 165 or 170*. Idk if this is relevant but it seemed strange. 

 

Any help is greatly appreciated. I'm really at a loss and I'm running out of time before I need to buy another temporary tag. 

Thanks again - Joe 

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