2003 QX4 - Perpetual OBDII "Gas Cap" Readings

[tjjarc]

I am the proud owner of a 2003 QX4 and been having an issue lately. The Service Engine Soon light tripped about a month ago and the OBDII reading suggested a "loose gas cap (ie, small pressure loss). After reseating the cap and clearing the code, the light stayed off for a week and then reappeared. I got it checked and received the same error code. Once again, I cleaned the gas cap and confirmed a tight connection and reset the SES light. A few weeks later, the light is on again.

Other than the light, the car is running great.

Could this possibly be a sensor issue? Should I try another gas cap? Anybody have any ideas?

Thanks.

[Q45tech]

During an emission test the cap is removed and is placed on a machine to verify it's performance.

[driftingmy240sx]

i would bet on a cracked evap canister or poorly seating vent control valve. that is if the code is an "evap small leak" code.

[MaximA32]

If it's a gross evap leak, I would check to make sure that there isn't rust built up around the filler neck.

[Alt.240.130]

You dont fill it up while the car is running do you?