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rashawn, ASE Certified Technician
Category: Car
Satisfied Customers: 393
Experience:  20 years in the industry A.S.E. master certified
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P0440 code in 02 cavalier...evap problem...acdelco company

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P0440 code in '02 cavalier...evap problem...acdelco company not sure if i need vent soleniod near fuel tank or intake manifold. i had transmission replaced last year, along w/ o2 sensor. light is still on...engine light on causes emissions test site to reject my car. i need to buy the correct part. thank you!

please help i'm a student teacher and need to get to the school. thanks!

EVAP LEAK DETECTED! without a smoke machine sometimes finding a leak can be difficult. First you must visually inspect your evap lines and hoses. Im sure you have done this. to visually see if they are all connected.and have no cracks or dryrot. As long as you do not leave the gas cap off often. which im sure you dont because you are aware of this. chances are very high that the problem resides with your fuel tank pressure sensor. very common problem with GM. the FTP sensor is built on top of the fuel pump unit. The only real way to verify is by monitoring voltages at the pcm. the PCM uses this sensor to see how fast the pressure or voltage drops after the purge valve (near the engine) shuts off and the vent valve (in back) closes. what happens is the FTP voltage begins to fluctuate and the PCM cant make heads or tails. OR someone installed a fuel pump and the o-ring is not seated properly.
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Customer: replied 7 years ago.
so it may not be a vent soleniode after all? i recall seeing something about pcm readings on the diagnostic chart....if i brought in the chart to the parts dealer will they be able to tell what i need? thanks for your help and i'll pay ya in a second
On a GM it is more times than not the FTP sensor. goes haywire. Hardly ever purge or never Vent. The only troublesome thing is when the o ring around the fuel pump has a leak. but mostly on the cavs its the FTP. EVAP is difficult to diagnose even with the smoke machine.