Evap p1440 and refuelling
 

Hi guys.

I've been struggling with the above code and its coming and going. Also been leaning towards thinking that tanks that are NOT full seem to help the issue.

For the past 3-4 days my torque app shows evap system ok even though the cel is lit. It takes time to clear, so ok.

Filled up this morning from 1/2 tank and BAM. Torque spit back evap/catalyst/oxy sensors not "complete" . The next cycle now shows just the evap incomplete.

So how can or how does refueling cause this? I have a new acdelco cap but unsure if it's actually doing it's job. Does the vent valve get affected during gassing up?

Can somehow the fuel level and the cap be still my issue? Was leaning toward a bad vent valve but now I'm stumped.

Thanks in advance.

While replacing the gas cap resolves the P1440 problem most of the time, it is not the only "thing" that can cause the code. Here are the possibilities from the FSM:

Incorrect fuel filler cap used
Fuel filler cap remains open or fails to close.
Foreign matter caught in fuel filler cap.
Leak is in line between intake manifold and EVAP canister purge volume control solenoid valve.
Foreign matter caught in EVAP canister vent control valve.
EVAP canister or fuel tank leaks
EVAP purge line (pipe and rubber tube) leaks
EVAP purge line rubber tube bent.
Blocked or bent rubber tube to EVAP control system pressure sensor
Loose or disconnected rubber tube
EVAP canister vent control valve and the circuit
EVAP canister purge volume control solenoid valve
Absolute pressure sensor
Fuel tank temperature sensor
O-ring of EVAP canister vent control valve is missing or damaged.
Water separator
EVAP canister is saturated with water.
Fuel level sensor and the circuit
EVAP control system pressure sensor
Refueling control valve
ORVR system leaks

I don't know why the code only happens with a full tank, but maybe the EVAP canister vent control valve or the EVAP canister purge volume control solenoid valve are causing this.

Thanks.

I will keep monitoring fuel level and the evap code issue to be certain if it causes issues but there's been other times that I thought fueling had something to do with it but was unsure. Now I will be more attentive and see for sure.

It just seems if a hose were an issue that in nearly all cases it would be bad ALL the time and not allow the code to come and go.

What a pain.

I had the same issue a few months ago and a replacement gas cap and a couple tanks with a couple bottles of this Redline fuel additive made it go away. I just passed NYC inspection.

I will check into that cleaner. Thanks very much.

I typically use chevron techron.

Its been a while since I've used a cleaner anyways and oil change is coming due and would be perfect doing it prior to oil change.