PO44O keeps coming up

Question

I have replaced the gas cap 4 times. Engine light stays on. Code PO440 keeps showing up. What do I check next?

Answer 1

HI there,

This is really a catch all code for the evap system. The computer is running the tests and sees there is a problem but can't really determine where the problem is.

The next step to take is to have a smoke test performed to eliminate any leaks in the system, then check the purge control solenoids and the vent control valve for proper function. The leak detection pump is a common failure on these as well.