Po440


#1

1998 Subaru Impreza outback- 2.2L manual.

The car had an engine light on and the owners took it to the Subaru dealer to read the code. They think it’s a gas cap issue- the code off the comp was PO440- Small evaporation leak detected? Are there any fixes for this? and my bro mentioned that it could be the solenoid that controls the gas tank pressure. See Pic!


#2

See pic below


#3

the usual and most common source for this code is … a loose gas cap. when you fill up, tighten the cap two clicks. sounds dumb, but its true!

it is possible that the cap has failed too. or the gasket on the cap is bad.

the first thing to do is tighten the cap and erase the code. drive it for a week, if the light comes on, get a new gas cap. then drive it for another week. if you get more codes, then take it in to have them dig deeper.


#4

Don’t just buy a brand-x gas cap if you decide to replace. On some models, it is critical and brand-x simply does not work reliably.

I just had for some months a P0440, with an occasional P0442 and/or P0446, on my 2002 Sienna. It turned out to be the charcoal canister assembly; there are some pressure valves there other than the VSV’s. Another man had the same problem on the Sienna Club, but he had two Sienna’s so swapped parts until the failure moved to the other car.

Since it was very intermittent, I chose not to pay a mechanic a couple hundred dollars to tell me there was no failure. So I stuck with it until I was confident, and told them to replace canister, and no trouble shooting. it seems to be fixed okay.


#5

The DTC code P0440 DOESN’T mean that there is a leak. The dealer (or, computer) is mistaken. P0440 is: “Evaporative Emissions System”. Another code DOES have the word LEAK in it. Something is wrong with any other part of the system; but, a leak has NOT been detected.