Code help on Chevy Blazer

[Blakers]

Guys, I have posted this question on two Blazer forums and no one replies. I don't think they are too mechanical over there.



Anyway, this is in regards to my wife's Blazer. She getting these codes:





Code help! P0446 & P0452

These codes keep popping up on our Blazer. One says Evap Emission Control System Vent curcirt. The second says Pressure Sensor Low.



What's weird too, is it sets each code twice.



Anyone know what these are caused by and what needs fixed?



Thanks,

Blake

 

[jmeehan]

I don't remember exactly how the system works, but your codes sound like they relate to the charcoal canister and it's system.



I'd check the canister and associated hoses for leaks. There is also a valve of some sort that lets the engine draw the fumes out of the canister at some point. This may be part of the problem, if it either doesn't open or is stuck open.



I'm hoping someone else will chime in here that knows the system better.

 

[Blakers]

Thanks. Do you know where the canister is on those. I looked under the hood and could not find one.



BTW, I forgot to say, but it's a 98 S-series Blazer.



Blake

 

[jmeehan]

Sorry but I don't know where the canister is. On some jeeps it was behind the left tail light, so it may be anywhere on you Blazer. If we still had my wifes I'd go look for it, but we traded it last fall for an '02 1500 RamOo.

 

[Philip]

Check the fuel cap and see if it is tight. On some GM's if the cap is loose it will throw codes at you.

 

[Hummin Cummins]

I've been through this same thing with my wifes. Service engine light comes on. Went to dealer and they pulled the same codes. Tested the system for leaks and found none. They reset the codes and I drove home, light came on 5 minutes away. Took it back, retested, and still no leaks. It's been like this for a two years now, hope it doesnt screw up the emissions test. We replaced the gas cap, no help there either.

Chris

P. S. Hers is a 98

 

[Blakers]

Thanks for the suggestions. I'm gonna hunt for that evap canister and see if there is anything wrong there. I've looked at the fuel cap and have not noticed any obvious problem, but I guess there could be a weak spring in the valve in it, or something similar.



It seems like the codes started when she filled it once without shutting it off. The alternator quit on her and her battery was dying and she needed gas, so I told her not to shut it off. Unfortunately the stupid daytime driving lights sucked the battery down and it quit before she got home. And this was in the day time - without the suicidal lights it would have run all day!



Blake

 

[Hummin Cummins]

Does your service engine light stay on constantly or only at certaitn times does it come on? I noticed with my wife's that only at certain fuel levels, the service engine light comes on. Also she quit packing it full, she quits when the pump shuts off the first time, this seemed to help, which makes me think its a pressure problem in the tank.

 

[Blakers]

Once it comes on, it stays on. I can clear it with my code reader, but it's back on in a day.