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GM Tech (Cam)
GM Tech (Cam), Pontiac Technician
Category: Pontiac
Satisfied Customers: 2373
Experience:  GM Grand Master Technician 2007. 14 years experience.
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On my car theres a PO442 showing on my Grand Prix GTP 3.8

Customer Question

On my car theres a PO442 showing on my Grand Prix GTP 3.8 Supercharged car. What could that be the I/M System Monitors All read green none are flashing or red. What could the problem be? Says small EVAP leak detected where could that be coming from andf how much does that cost to fix Or could I do it myself im not certified but I can do basics?
Submitted: 1 year ago.
Category: Pontiac
Expert:  Gary replied 1 year ago.

Hi Tom,

This is very common on many cars.

First thing to check is the gas cap.

The seal can harden with age and use, and it might not seal well enough at the filler neck.

Or it could have a weeping pressure vacuum valve.

You can apply a smear of rubber grease to the seal and see how well it makes contact to the filler neck.

Then if the cap is the cause, replace the cap first.

The evap purge solenoid is usually the next cause.

Can you try as I have suggested above with your gas cap?

Gary

Customer: replied 1 year ago.

Yes i will try that then I will jump out the evap purge solenoid if I undo the connector and put jumper wires postive to one side and negative to the other side I should hear the solenoid open and close right? Instead of changing it I can check it that way?

Expert:  Gary replied 1 year ago.

I would listen to the solenoid while the engine is running.

It should be ticking like an injector.

Then I would measure it's resistance.

Typically about 20 ohms.

It may be a 5 volt circuit, so until we get a circuit, I would not put 12 volts across it.

Gary

Customer: replied 1 year ago.

Ok thank you very much

Customer: replied 1 year ago.

Where would I get 5 volts from could I use a 9 volt battary? Or should I just measure Ohms?

Expert:  Gary replied 1 year ago.

Can you measure ohms first and come to back to me?

Gary

Customer: replied 1 year ago.

Yes thanks alot??

Expert:  Gary replied 1 year ago.

Hi again,

It should be switched 12 volt from the PCM, so you could test the solenoid with 12 volts.

What resistance does the solenoid measure?

Gary

Customer: replied 1 year ago.

Thanks

Expert:  Gary replied 1 year ago.

Another trick you can try is to take the solenoid away from the engine, cap the fittings, and run the engine. If the code doesn't reoccur, then start introducing each part of the system. This can work if the code comes up quickly.

Gary

Customer: replied 1 year ago.

I checked the purge valve soleniod and read through the connect for power 11.96 volts and 21 OHMS through the soleniod. Just cant tell if its opening and closing with the engine noise and the supercharger noise cant hear nothing opening or closing through the purge valve. How would I see if it is the once thats done I can move on to the next thing if its good or bad?

Expert:  Gary replied 1 year ago.

With the hose off the solenoid, you should hear a vacum leak through the solenoid with the engine running.

Gary

Customer: replied 1 year ago.

Ok thank will try..

Expert:  Gary replied 1 year ago.

Hi Tom,

Have you had any luck yet?

Gary

Customer: replied 12 months ago.

Yes I checked the purge valve soleniod and its working what next? My ODB2 Is telling me I have a Small EVAP Leak? Code PO442

Expert:  Gary replied 12 months ago.

Hi Tom,

Did you try as I mentioned on 2nd December?

Does the code still set then?

Gary

Customer: replied 11 months ago.

Yes I tired that aslo and still saying po442

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