Help P0440

[ysteve]

Hi guys, i keep having this p0440. I change the gas cap but it still coming back every 3-4 days. I check vacuum lines but never find a leak. Maybe there is some spots wich you gonna recomend to check? Or its not because of leak? Any questions go to "No cat".
Thank you

[richtazz]

With a P0440 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:

Remove and reinstall the gas cap, clear the code, and drive for a day and see if the codes come back.
Inspect the EVAP system for cuts/holes in tubes/hoses
Inspect for damaged or disconnected hoses around the Evap purge solenoid
Check and/or replace the sensor
Check and/or replace the purge valve
Have a professional use a smoke machine to detect leaks

Since you've tried many of the tests, I think a professional smoke machine test is your next step.

[BostonKev]

is the sensor located up under the drivers rear fender or on closer to the tank?

[BNaylor]

Originally Posted by BostonKev

is the sensor located up under the drivers rear fender or on closer to the tank?

The sensor (pressure) used to monitor vacuum decay in the evaporative emissions system is located at the top of the fuel pump assembly located right on top of the gas tank.

The P0440 DTC indicates it is a large or gross leak.

Sorry ysteve it took a while for me to get to your PM.

[BostonKev]

thank you for the info.
Not to butt in on the thread but I had the same code and after I would reset it it would come on roughly a day later. I removed and inspected all the all the rubber hoses going to the canister up under the rear quarter also on the hose that heads to the top of the tank. I placed a little bit of silicon on the end of the hoses thinking it would help make it air tight and it only comes on every week or so now which makes me believe the actual issue might be the canister itself. Does that make any sense? BTW, the gas cap has already been replaced.

[BNaylor]

Originally Posted by BostonKev

thank you for the info.
Not to butt in on the thread but I had the same code and after I would reset it it would come on roughly a day later. I removed and inspected all the all the rubber hoses going to the canister up under the rear quarter also on the hose that heads to the top of the tank. I placed a little bit of silicon on the end of the hoses thinking it would help make it air tight and it only comes on every week or so now which makes me believe the actual issue might be the canister itself. Does that make any sense? BTW, the gas cap has already been replaced.

I would recommend checking the vacuum lines from the charcoal cannister to the purge solenoid located engine side. It looks like you have the other bases covered. According to the GM service manual a faulty or damaged charcoal cannister can trigger a P0440, therefore it makes sense to me. That applies to a 3800 or 3400 equipped Impala.

[BostonKev]

can I trouble you to tell me where I can find the purge solenoid? It's a pain to track these things w/o a lift. Thank you

[BNaylor]

Originally Posted by BostonKev

can I trouble you to tell me where I can find the purge solenoid? It's a pain to track these things w/o a lift. Thank you

Which engine do you have?

[BostonKev]

3.8 police

[BNaylor]

Originally Posted by BostonKev

3.8 police

Passenger (right) side of engine in front of the UIM/plenum. Circled in red in the pic.

[BostonKev]

thank you

[LeapFrog777]

I'm curious did this p0440 problem ever get resolved? If so how was the correction made. Thanks.

[ogre73]

I'm curious, where would the solenoid be on the 3.4L? I have had this code for over a year now, and have another inspection coming due soon. I would rather fix it then try to trick the inspectors again.

[BNaylor]

Originally Posted by ogre73

I'm curious, where would the solenoid be on the 3.4L? I have had this code for over a year now, and have another inspection coming due soon. I would rather fix it then try to trick the inspectors again.

If you are referring to the purge solenoid, it is located to the right of the throttle body bewteen the IAC and EGR valve. See pic below.

[ogre73]

Thanks! I will check it and see if that gets rid of my problem. Haynes isn't descriptive enough to tell me where it was, so again, thank you.