Engine light on! Help me out!

**Vinson clark** · 06-04-2012

Hello everyone my name is vince, i own a 2006 Pontiac grand prix with 98200 miles on it. I should have joined this forum back in 2006 when i bought the car i just found this forum and it has tons of helpful information. This morning when i started the car the check engine light came on i drove it to work (50 miles one way) after i got off of work i had the code read. These are the probable causes 1. purge or vent solenoid failure 2. plugged evap canister condition 3. failed evap pressure sensor. Its also saying ECM has detected pressure in the EVAP system during a non purge condition. Where do i start anyone have any suggestions? I need to drive the car to work tomorrow as well will this hurt anything? The car seems to run fine like it always has i commute 100 mile round trip though and dont need the car to let me down. Thanks in advance for any help.

**bmx6454** · 06-05-2012

you haven't noticed any decrease in mpg?

**Vinson clark** · 06-05-2012

Yes now that you mention that my gas mileage has went down some

**bmx6454** · 06-05-2012

i would definitly start with checking the evap canister first then. not sure exactly how to test this, im sure someone else on here does.. but this wont hurt the car, just make it run rich.

**BillBoost37** · 06-05-2012

Vince..did they happen to give you the actual code number? We can often suggest more direct advice when we have the code. If not..it sounds like this might be an evap leak or purge failure code?

**Vinson clark** · 06-05-2012

Code number P0496 sorry about that man

**BillBoost37** · 06-05-2012

Found this quickly on it.

Code P0496 is defined as "Evaporative Emission (EVAP) System Flow During Non-Purge"

If the Evap purge valve does not seal properly, fuel vapors could enter the [COLOR=green !important][COLOR=green !important]engine[/COLOR] at an undesired timing causing drivability concerns. The [COLOR=green !important][COLOR=green !important]control [COLOR=green !important]module[/COLOR][/COLOR][/COLOR] tests for this by commanding the EVAP purge valve OFF closed and vent valve ON closed, sealing the system, and monitoring the FTP for an increase in vacuum. If the control module detects that Evap system vacuum increases above a calibrated value, DTC P0496 will be set.

Read more: What does the engine code P0496 mean - JustAnswer What does the engine code P0496 mean - JustAnswer[/COLOR]

**Vinson clark** · 06-05-2012

Where is the evap can on a 2006 pontiac? I'm assuming the purge valve is located on the evap can?

**99XC600** · 06-05-2012

Originally Posted by Vinson clark

Where is the evap can on a 2006 pontiac? I'm assuming the purge valve is located on the evap can?

Driver side, behind the rear wheel and in front of the filler neck.

Very easy to get at. Basically held in by a single bolt and a mounting flange to the body of the car. Don't forget to wear your safety glasses, when removing. I will virtually guarantee, that you will get stuff in your eyes as your looking up trying to remove it. Ask me how I know

**Vinson clark** · 06-05-2012

Thanks man, I've got a purge valve ordered I'm going to pick it up in the morning and install it. I will report back if this solves the issue. Can you get to it without having to jack the car up?

**99XC600** · 06-05-2012

Originally Posted by Vinson clark

Thanks man, I've got a purge valve ordered I'm going to pick it up in the morning and install it. I will report back if this solves the issue. Can you get to it without having to jack the car up?

All depends how fat you are... LOL

**Vinson clark** · 06-05-2012

I cawled under the car and looked at it when I got off work. Where exacly is the purge valve on the thing? When I looked up at it I noticed some wires running into it with a plug that looks like you can just unhook is this what I'm looking for or will I have to pull the whole evap can out? It's not very big just a small little can.

Another question after I drive my car for a while and get it up to operating temp and then turn it off and try to crank it back up it will turn over about 3 or 4 times but will not start, then when I try it again it will turn over about 3 times and then start. Would a purge valve in the evap be causing this? It only does it after the car has been running for a while.

I just had the fuel pump replaced about a month ago if that matters.

**Fivefingerdeathpunch** · 06-05-2012

Clean your MAF sensor and throttle body.

That should help alot with the crank/stalling at start up.

**Vinson clark** · 06-05-2012

Sorry for my lack of knowledge but what is a MAF sensor? And whats the best thing to use to clean these things with?

**Fivefingerdeathpunch** · 06-05-2012

Tb - tube - maf sensor- tube - air box.

Thats pretty much how it goes on your car, you cant miss it, its the only connector in the intake tubing, take that out along with the the tubing and get some maf cleaner from napa or where ever and spray it down. Then unbolt the throttle body and clean that, I am willing to bet its all black and nasty.

**GTP in RTP** · 06-05-2012

change your gas cap

**99XC600** · 06-06-2012

Also, check your fuses in the PDC that is located in the engine compartment. Especially #21. I chased a MAF sensor issue for a couple of weeks until I realized that I knocked the fuse out of the terminal when changing the battery.

Cleaning the MAF is pretty straight forward, Just remove the MAF from the engine and use the correct cleaner. They make a MAF cleaner specifically for this purpose. Don't use brake cleaner or throttle body cleaner on the MAF or you will ruin it.

The throttle body get's caked up with carbon deposits as a result of the EGR system pumping exhaust into the Intake on cold mornings. Since the Grand Prix has a drive by wire system, it needs to know where absolute zero is with the throttle plate closed. Once the throttle plate gets gunked up with carbon deposits it throws off the reading to the computer.

Cleaning of the throttle body is easy as well. Once you have the MAF removed. Removal of the throttle body is just a matter of removing the electrical connector and then removing the 4 fasteners that hold it to the intake. Do this while the engine is cold. The throttle body has coolant passages within it. You don't want't to get burned when you remove it. Once removed, purchase some throttle body cleaner and use a soft toothbrush to clean it up. I found it was easier to spray some of the cleaner into a small container and dip the tooth brush into it versus spraying the throttle body. Take your time, it will cleanup.

**Vinson clark** · 06-06-2012

Replaced my evap can today. Also cleaned my maf sensor and throttle body, replaced my air filter while I was at it. Hopefully all is well now I will report back if another problem shows up. The throttle body was really black. Hopefully this solved my starting issue.

**Vinson clark** · 06-10-2012

Engine light came back on this morning I'm assuming its the same code. It will be tomorrow morning before I can have it read again. I replaced the evap can by the filler neck its a small plastic black cylinder object, I'm assuming this is the evap can anyway. Where to start now anyone have any ideas? Car seems to be running fine my instant economy is about 28-32mpg doing 70mph so there is no real loss in fuel mileage.