Mechanics

CODE P0440 EVAP EMISSIONS

2000 Chevrolet Astro • 147,000 miles

This van has had this same code reoccur every few days for the last year (since I bought it). I was told that it was just due to a bad gas cap. I replaced the gas cap, and the battery (the battery it came with was very weak). The code stayed away for at least a couple weeks after replacing the gas cap and battery. I have ignored the code since then, until now, because I need to pass emissions testing. I have cleared the code 5 times now, and I run it for at least 2 or 3 drive cycles, and it comes back. The Freeze data showed that it tripped once while cranking (400rpm) so I erased the code and data. And the last time it happend while accelerating (1000rpm 3mph). I have heard that it could be a bad fuel pump, EVAP CANISTER PURGE SOLENOID VALVE, or even just a bad battery. I am not sure where to look first.
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Electromdc
October 14, 2011.



I would be checking all ECAP vacuum hoses first, ensure that they are free from cracks and tight on all spouts, as the care is nearly 12 years old, I would be considering replacing the charcoal canister as well, start here.

Mhpautos
Oct 14, 2011.
PO440 is a generic code for the EVAP system. There will likely also be more specific codes to help diagnose it but you will likely need a smoke machine to even get started

Wrenchtech
Oct 14, 2011.
EVAP canister is on the driver side of the gas tank, and I inspected both vacuum hoses connected to it, as well as the fat rubber hose. None of them seemed to have cracks or be loose. I purchased a new canister. Might replacing the canister fix the issue, or is that less likely? Or might the leak be in the line further forward on the vehicle (after the vacuum line converts to steel tubing)? How can I check for leaks other than visually, without a smoke machine? Or is it time to take it in, to have them use a proprietary code reader and perform smoke machine test?

Tiny
Electromdc
Oct 19, 2011.
I checked the hoses that connect directly to the EVAP canister, all were free of cracks, and securely connected. Should I just replace the EVAP canister and see if that fixes things? Or do I need to pay to have a smoke test done?

Tiny
Electromdc
Oct 19, 2011.
You're just spinning your wheels without a smoke machine. That leaks could be anywhere, including one of the solenoids.

Wrenchtech
Oct 25, 2011.