P0452 p0453


muzzy1maniac
09-13-2007, 02:19 PM
I'm getting both of these codes. I'm in the process of going thorough all the lines and connections now. I had a code for a small leak a while back but never did anything about it. Now that code( can't remember the #) is gone and I get the 52 & 53.

The other problem is that is seems the 4wd doesn't like shifting out. I'll be driving and get a loud humming/vibrating sound that goes away when I hit the 4hi button. I can then put it back in 2wd and I'm good for a while. There is no ryhme or reason when it comes back. Sometimes 10 miles sometimes 150.

Are these possibly related? Vaccum or electrical maybe?

old_master
09-13-2007, 08:22 PM
P0452 and P0453 are EVAP pressure too low, and too high respectively. EVAP system faults are among the most difficult to track down. You may find a poor connection at, or a faulty pressure sensor, (on top of the fuel tank), or a poor ground for the sensor. Could even be a faulty fuel tank cap, but doubtful. The purge solenoid, located on the passenger side of the intake manifold might have a poor connection, poor ground or is leaking. The canister purge vent solenoid, located on the crossmember in front of the tank on 1998, might have a poor connection or ground, or the solenoid itself might be faulty. There's a couple of things for you to check. The P0456, (EVAP system very small leak), you were getting may have been the beginning, or related to the DTC's you're getting now. Sorry for the broad list of possibilities, but welcome to the EVAP system diagnostics ;)

muzzy1maniac
09-23-2007, 06:36 PM
On a whim I droped the charcoal canister and canister purge solenoid. Put my compressor to the canister and a large puff of dirt flew out! Did the same to the solenoid - it was a dirty freakin mess in there. Blew out everything and my light has been out for the last 300 miles.

old_master
09-23-2007, 08:26 PM
LOL Good job! I don't recall ever seeing that procedure in the shop manual. Maybe you can write to GM and have them add that step!

muzzy1maniac
09-24-2007, 08:39 AM
LOL Good job! I don't recall ever seeing that procedure in the shop manual. Maybe you can write to GM and have them add that step!


It's under the I'm too cheap to keep throwing parts at this beast and way to cheap and untrusting to pay someone. It really came to me while inspecting the lines. The canister etc is probably in the worst locations possible. All the crap we drive through ends up there. The stuff I cleaned off the rails and outside of the canister would cause a CSI to get wood.

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