2000 grand prix service engine soon light

My girlfriend just got a 2000 grand prix with 96 k on a 3.8. The other day when i was driving it the service engine soon light came on so i checked the gas cap and reinstalled it. soon after the light went out. Now its back on. this is all over a 3 day span. any other trick to try? does auto zone still do that code reading?

Best thng to do is get it scanned. Last time I checked Autozone still does it for free as long as the SES/CEL light is on.

Just be careful of A-Z's code definition. You'd be best off to have them scan it and get the actual codes, post them here, and we'll get you the real definition. I had a guy say they told him a p0300 (random misfire) meant he needed oxygen sensors (which seems to be their answer for just about every code involving fuel mixture and/or misfires).....NOT!!!

Did you or her just put in a different type or maybe old gas in the car recently? That could be the reason it's on (happened to me & the light went out after all the "bad" gas was out).

Okay so Autozone says the code is p0452 which is " The pcm has determined that the voltage signal from the presssure sensor in the evaporative emission control system is too low for the current engine operating conditions". "probable causes" 1. fuel tank pressure sensor defective. 2. check connector and wiring 3. check hoses and fittings.

Now could this also be a bad fuel cap thats letting pressure out? any feedback is great!!!!!
Thanks Derek

DTC P0452 is typically an electrical problem related to the pressure sensor located on the top of the fuel pump pod. It could be the sensor, the electrical connector or wiring. As part of the diagnostic the PCM checks for a fuel tank pressure sensor short circuit which is the only time it should generate a P0452 DTC. DTC P0440 is the gas cap code and indicates a large leak in the evaporative emissions system.

Have you had any work done on the fuel pump assembly?

not to my knowledge, shes just had the car a little over a week. Whats the easiest way to get to the fuel pump area to check things out?

We have a thread at our Tips & Maintenance forum that covers it. Easy to remove the access cover located behind the rear passenger seat and in the trunk. See link below.

Click here (http://www.automotiveforums.com/vbulletin/showthread.php?t=739278)

The pressure sensor is the black part located on top of fuel pump assembly.

http://i5.photobucket.com/albums/y186/lizzywiz/fuelpump_top2.jpg

thanks that link helps me out alot... That is exactly what i needed! So i just get to and take the old sensor out and put the new one in (which is on order). Theres nothing i should know? tips, tricks, do's or don'ts.....Thanks again

well i replaced the Fuel Tank Pressure Sensor. Had the code cleared and it returned. It comes back as the same code.... I inspected the connector when i replaced it and it looked clean and free of defects. The error code calls to inspect wiring and hoses. I am uncertian of what hoses I should check... Please anymore ideas or thought are great as I'm in college and money is of the essence...

The next step since it doesn't cost much is to check the PCM 5 volt reference signal at the pressure sensor electrical connector which is wiring to include signals. Use a digital multimeter - DMM. The FTP sensor provides a low reference signal ouput based on pressure it senses between air pressure and vacuum in the evaporative emissions system. One parameter to set P0452 is the output of the sensor is .1 volts or less which is clearly abnormal and the abnormal condition is present for more than 5 seconds. The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. See table below.

http://i5.photobucket.com/albums/y186/lizzywiz/ftp.gif