22mr2

This one drove me nuts for a few days, so I figured Id at least post the results to save someone else the aggrevation that it caused me. When it first showed up, I applied vacuum to the egr valve to see if it was moving and holding. A nice solid clunk when vacuum was applied, another when it was taken away. Also did this with the truck running and it stalled as soon as the egr valve had vacuum. Did resistance checks on the egr temp sensor(only on california trucks) and they checked out fine. Checked the egr solenoid valve, tested fine and so did the modulator valve. Triple checked vacuum routing and it all checked out. Blew carb spray through the vacuum ports in the throttle body to make sure they werent plugged. They werent, but one of the steel lines that are in that huge mess of steel vaccuum tubes was plugged solid. If you happen to run into this code and all the basics check out ok, start pulling off vacuum lines one at a time and make sure you can blow through them easily and if you find one thats plugged, just bypass it with a piece of vacuum hose. Pull the efi fuse for about 30 minutes, code will be gone, but it will take a few drive cycles for the ecm to throw the light back on if the problem still exists.
I had no driveability issues with this code, no idle problems, only poor fuel economy(15mpg)I also was unable to fix this right away, which led to 2 more codes(25 lean mixture) and (27 O2 sensor signal). My guess is the ecm sees the extra air from the egr making it lean and just keeps adding fuel, which fouled out both o2 sensors. 2 new sensors later and were up to 21 mpg and no more light. Hope this helps someone out! Sorry for the lack of pics!!

22mr2

oops forgot to say the truck. 94 pickup with a 22re california emissions.

zlathim

Good post 22mr2. It will probably be of great use to someone who searches for threads related to this code. Well done.