CEL Code P0440 - Evaporative System Malfunction, Large Leak

[Kigiin]

I have gotten this code twice before. Once right after installing aux fuel tank. Mechanic and I's theory was that charcoal canister was getting overwhelmed from aux tank. Replaced canister with a used one and code went away. The second time was about a year later, but this time it was only a pending code and never actually threw a CEL.

Now several years later, this morning on way to airport, popped up again throwing the CEL. I cleared it right before parking but think it will return again when I pick it up tonight.

Those canisters aren't cheap, especially when I am about to sink $1,500 for the 90k service next week.

Any thoughts on how to exactly diagnose this code?

 

[Kigiin]

Anyone? Even anyone that recently stayed...

 

[phippsj]

I prefer the Hampton. However, I have had this code and solved it with a new fuel filler cap. Either the o- ring has hardened up or it's not tightening properly.

 

[Kigiin]

Well the cap came with the aux tank and still appears to tighten snugly. I cleared the code yesterday morning and it hasn't returned so not sure what to think.

 

[cpcc]

happens if both tanks are topped off, on hard turns. Not a big deal. Reset it and your good to go. Just avoid these situations and youll be fine

 

[lrowe_csp]

I have been getting it intermittently on my 1999, but it is appearing about every couple of tanks of fuel now. I changed the gas cap (OEM Toy) but that has not helped. Does this code only refer back to a leak in the evaporative system? The canister is expensive, as you mention, so I don't want to replace it on a hope and a prayer, but will replace if there is some reasonable certainty that this is the likely problem.

 

[Kigiin]

Well I didn't have both tanks full. Actually the aux was empty and main was half full.

I cleared it last Wed and it hasn't reappeared so hopefully it was just an oddball thing.

When I was getting it regularly years ago, replacing the canister definitely fixed it. However in retrospect, I got lucky as it could have been other things, such as the gas cap.