I saw a YouTube video about Subaru evap canisters and the guy said the dealer told him the canister’s maximum weight is 2.5 pounds and needs replacing when it exceeds the maximum weight. My check engine light for P1440 comes on a couple times a year and goes out by itself. It’s been doing this for four years. The car is a 1998 Forester with 271,000 miles on it and the light has been in for a week.

 

Can anyone verify this about the weight? I weighed mine this morning and it was 3 pounds 3 ounces.

It's not your problem. The computer can't detect the weight of the canister. P1440 is a system leak. You need to test the system with a smoke machine. Being in Alaska, and being a Forester- you probably have rust pin holes in your fuel filler neck. 

 

GD

If there were pinholes in the filler neck wouldn’t we loose vacuum in the fuel tank. When I remove the gas cap there is plenty of vacuum.

 

We don’t get much vehicle corrosion here in interior Alaska since they use very little salt on the roads. Also we have a fine dry power snow instead of heavy wet snow.

 

The hoses to the canister and purge valve appear to be solid.

Well it's important to check for leaks and also to verify operation of the purge solenoid, etc. Ensure the purge solenoid is electrically good and that it opens and closes correctly. 

 

GD

So I can plug in those green plugs under the dash on the drivers side to see if it closes the valve?

I am not sure if that will cycle the purge solenoid or not. It may. If not just remove it and bench test it. 

 

GD

Yep, it does cycle the purge valve open and closed. I blew through it and it definitely closes. But that doesn’t necessarily mean that it doesn’t need replacing?

 

Even though the computer doesn’t weigh the canister, is it supposed to be replaced when it exceeds a certain weight?

<p>I have never fixed an EVAP code by replacing the canister, regradless of condition. Is the canister likely to be less functional than a new one? - absolutely. Is it going to fix your 1440 code? Almost certainly not. </p>

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<p>I would be looking at the fuel tank pressure sensor and circuit as well given the EVAP solenoid seems to be working. This is not a data item that is available through generic OBD-II live data. It will require either a Subaru Select Monitor or direct measurement of sensor input to the ECU. </p>

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<p>GD</p>

Edited November 20, 20178 yr by GeneralDisorder

No. The only reason they ever need to be replaced is of they get flooded with liquid fuel from overfilling the tank. Typically a flooded canister will weight 4.5lbs or more.