OBD code P0440

If this is on your S Blazer the problem is probably the vent solenoid tucked up under the spare tire. That or the line running to it. They get dusty inside and the "seal" doesn't. I have replaced a LOT of them. The hardest part is usually getting the spare out of the way (you can change it with the spare in there but it is MUCH MUCH easier with it down).

That code is a PIA to test without a smoke machine and a code scanner. You have to cycle the system and see if it leaks.

To check the cap is easy. Look at the seal it has that seats against the fill pipe. If it's cracked through or missing then it could be the cap. That can be tested by erasing the code, making SURE that the conditions for running the EVAP test are there and placing a sandwich bag over the cap and putting it back on. The bag will seal the pipe and then you run the drive cycle that would set the code. If you still get the code it isn't the cap.

is what the part looks like. You don't HAVE to replace the hose though. usually you can trim the end and it will fit on tight enough to hold. If in doubt a clamp will hold it just fine.

Thanks, that's totally useful. I greased the gas cap, see if that helps. The spare, well, the cable hoist rig doesn't work. So, the spare is up there with some big nylon tie straps. I'd have to cut the straps, and then go through the routine of put the tire back up under there. It can be done. In any case, thank you very much.

Yeah the spare winch can be a real POS... I have replaced them a couple times.

I have also cheated and used a ratchet strap run from the center hole up over the spare carrier and over to the frame.

Oh, bother! I hadn't even thought of a ratcheting cargo strap. and, I was just about to buy a couple of them at Harbor Freight. Thanks for the great idea.

I sprayed the gas cap and socket with white lithium grease. And, the Blazer passed an honest inspection, this morning.