1995 k1500 code 32

Joeyblaze · January 7, 2019

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

Edited January 8, 2019 by Joeyblaze

riverbanks · January 8, 2019

Got to think of a test for that,is the command being sent and full ground

Doug_Scott · January 8, 2019

There are two sides to this issue isn't there? You have throw all the mechanical parts at it, it would seem to me that you may be overlooking something in the electrical side.

This is going to sound stupid, but, when they test do they actually connect a scan tool, or do they simply use a sniffer and look for a light on the dash? Reason I ask is that about 15nyears ago I installed a centrifugal supercharger on a 2000 ML320 Mercedes. This kit was from Mosselman, and would set a check engine light if you ran under boost too long for the evap syztem. At the time we had emission testing on rollers. There was an at idle test and then a simulated.ighway test. I knew it would fail the highway portion. When it came time to test it, it passed with flying colours. Seems AWD vehicles had the idle test, and a test at 2000 rpm in park. The inspection stations only had one set of rollers. And since it couldn't use the rollers, no ECM connection, just an inspection to see if the CEL light was on during the test. I had pulled the bulb out as a "Hail Mary", ,just in case, effort and it paid off. They didn't even bring it into the shop. They backed the truck up to the shop door, ran the sniffer out the door into the exhaust, and used the tach in the dash to do the highway test. It passed the sniffer test easily, he only needed to rest his foot on the gas pedal to get to 2000 rpm. After I got the truck back to my buddies place I stuck the bulb back in and found it had set the CEL on the way to the shop. Merging into traffic on the 401 set the light. I finally resolved the CEL issue by putting two big vacuum cans on it. That truck missed the grandfather limit by a year. Then the government just killed the entire program last year, saying it served its purpose and got the worst cars off the road.

Joeyblaze · January 8, 2019

1 hour ago, Doug_Scott said:

There are two sides to this issue isn't there? You have throw all the mechanical parts at it, it would seem to me that you may be overlooking something in the electrical side.

This is going to sound stupid, but, when they test do they actually connect a scan tool, or do they simply use a sniffer and look for a light on the dash? Reason I ask is that about 15nyears ago I installed a centrifugal supercharger on a 2000 ML320 Mercedes. This kit was from Mosselman, and would set a check engine light if you ran under boost too long for the evap syztem. At the time we had emission testing on rollers. There was an at idle test and then a simulated.ighway test. I knew it would fail the highway portion. When it came time to test it, it passed with flying colours. Seems AWD vehicles had the idle test, and a test at 2000 rpm in park. The inspection stations only had one set of rollers. And since it couldn't use the rollers, no ECM connection, just an inspection to see if the CEL light was on during the test. I had pulled the bulb out as a "Hail Mary", ,just in case, effort and it paid off. They didn't even bring it into the shop. They backed the truck up to the shop door, ran the sniffer out the door into the exhaust, and used the tach in the dash to do the highway test. It passed the sniffer test easily, he only needed to rest his foot on the gas pedal to get to 2000 rpm. After I got the truck back to my buddies place I stuck the bulb back in and found it had set the CEL on the way to the shop. Merging into traffic on the 401 set the light. I finally resolved the CEL issue by putting two big vacuum cans on it. That truck missed the grandfather limit by a year. Then the government just killed the entire program last year, saying it served its purpose and got the worst cars off the road.

Since it's obd1, they can't connect a scantool. They use the sniffer and visually inspect it. If I shut the truck off before I take it to the e check, the engine light will turn off. However, when the test actually happens, the sniffer reads high nox. Then back at home, I can check for codes and it shows a code 32.

riverbanks · January 8, 2019

Still researching,so if command is sent,it could possibly be cut off by perameters not staying steady,1,steady throttle with less than 2% change?,so back to vacuum guage, check for steady needle

JD110 · January 20, 2019

Code 32 is a egr solenoid code. Torque converter clutch is also on that circuit. It is on the same driver from the ecm, if your tcc solenoid is shorting out it will prevent your egr solenoid from working.

DirtyDan23 · January 11, 2023

On 1/7/2019 at 6:54 PM, Joeyblaze said:

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

I know this post is old and this is a Hail Mary shot but I just bought a Chevy version of your truck and it’s throwing the same 32 code. I was wondering if you resolved your issues or what happen? Thanks Dan