2002 LB7 Can't Pass Smog

[Mark Meyers]

I have a 2002 K2500HD with the LB7 Duramax, there are no DTC’s set and none in memory. I however cannot pass Smog (California) because the EGR Monitor will not set. I have driven the crazy GM drive cycle several times still it will not set, I have put about 400 miles on it since last checked and it still does not set and no DTC’s. I scanned the system and found one item out side of the norms but it is not setting a DTC. It is the EGR Vacuum Sensor which GM states should be between 18 – 158 and mine is setting at 11 at idle and when rpm is increased will go up to 15 but no higher. Could this be the issue and if so what controls this pressure and how do I correct it. Any help is appreciated, my local dealer is no help and I honestly believe I know more about the truck then they do and that is both scary and disappointing.

[Kennedy]

I've never really done any troubleshooting on these, but it sounds like maybe the vacuum pump could be weak. I would start there with diagnosis making sure that the pump can produce 25"+ direct from the pump with a steady needle.

[More Power]

I have a 2002 K2500HD with the LB7 Duramax, there are no DTC’s set and none in memory. I however cannot pass Smog (California) because the EGR Monitor will not set. I have driven the crazy GM drive cycle several times still it will not set, I have put about 400 miles on it since last checked and it still does not set and no DTC’s. I scanned the system and found one item out side of the norms but it is not setting a DTC. It is the EGR Vacuum Sensor which GM states should be between 18 – 158 and mine is setting at 11 at idle and when rpm is increased will go up to 15 but no higher. Could this be the issue and if so what controls this pressure and how do I correct it. Any help is appreciated, my local dealer is no help and I honestly believe I know more about the truck then they do and that is both scary and disappointing.

Just a thought... Are there any aftermarket programming or devices installed? For a time, the aftermarket was big into defeating the EGR - then the EPA got involved. Your local dealer could update the vehicle ECM programming with the latest revision software for that model. It'll overwrite any aftermarket programming. If you haven't owned this truck since new, you might check for any "EGR delete" parts installed.