Code P0440

[munsterlander]

Hello.

 

I have a 1999 GMC Sierra SLE Ext Cab 4X4 with a 5.3L engine, 4spd auto, and apporx 106K miles. Put 10K miles on truck this year with no issues. Clean truck from southern Colorado and now 2 years in New York. Very little Rot/Rust which is impressive for Upstate New York.

 

Parked truck approx 1 month ago with no SES light or other issues at all, but when started approx 1 week later I was greeted immediately with the dreaded Service Engine Soon light. Scanned PCM with code reader and had P0440 EVAP code. Replaced gas cap (per AutoZone) but did not fix. Went through a tank of gas (many start up cycles) but SES light still on. Checked Purge solenoid and seems to work fine with 12V applied. In fact valve holds tight and wont let air pass through. Replaced vent solenoid as with 12V applied it would not engage. Removed charcoal canister and seems fine and will also hold air pressure without leaks. Checked all lines as best possible and see no cracks or leaks. Checked fuses and all OK. Fuel consumptions seems average for this time of year (cold) and I dont smell fumes near gas tank either. Note I removed positive from battery to reset computer after each change and/or test but still have issue. Ligh on solid immediately after start up and stays on.

 

Did not test with smoke/pressure tester as $$ is limited.

 

Please, any assistance is appreciated.

 

Thank You!

[grose67]

I had this same code after I flooded the crankcase with antifreeze. I took the tube off the top of the canister that runs to the solenoid as well as the rubber hose that leads to the side of the canister. I carefully blew some air through the canister. WHen I buttoned it back up, I was able to clear the code and so so far it has stayed off.