P0457 Evaporative Emission Control System Leak Detected (Fuel Cap Loose/Off)

IBratmanI

IBratmanI

Subaru Ambassador- AdidaSubarus
I keep getting this code, and now it's every time I get gas. I tighten the gas cap as tight as I can, and still get it. And on top of that, when ever I get gas, it has a hard time starting after. I sometimes have to hold it to the floor to get it to fire up. Is this all because my gas cap isn't getting tight enough? This is the only time it does any of this, the rest of the time I don't get any codes, and it always starts fine. Any ideas?? Do I need a new gas cap??

 
did that code say the size of the leak, very small, small, large???? theres no way an evap problem could stop the car from statring, all it does is recirculate fumes from the tank to be reburned to be more efficient. check for any rust on the lip of the filler neck, look at the gasket on the cap, is cracked or worn funny. the easiest fix is simply swapping out the cap, also the cheapest. If that doesn't fix the issue a smoke test is in order to locate the leak, closing the vent valve and sealing the system, through the evap port under the hood, big green cap a smoke is sent through the system hopefully locating a leak.

 
It says nothing about the size of the leak, it just says my gas cap is loose. The cap seems to be fine, nothing obvious

 
I don't know if this pertains, and I don't remember the particular code, but I had something like that when I first got mt WRX. Behind the alternator there is a blue colored (on my car) plastic T that has 3 vacuum hoses connected. One of them was disconnected on my car. This may not be your problem, but it will take you about 5 minutes to check it out.

Just a shot in the dark. Hope it helps.

 
Thanks John, I do plan on looking further into any hoses under the hood as well. Hopefully it's something simple!!!

 
PO457 can be a pisser to suss out

loose fuel cap -- or a dirty one that doesn't seal well to filler neck, whcih can also be dirty. a bit o PB Blaster on filler thrreads and sealing surfaces can work wnders

rust perforation in filler neck - this will fool ECU and it'll give u the PO457. not as easy to suss out, and a lot harder to fix. subies are notorious for rusting filler necks, it's a medium-big PITA to replace the part.

evap canister plugged/leaking -- this should give u a diff code, but not always. chec to see if hoses to evap cansiter are good and well connected

 
I forgot to update, but it didn't work. I still get the code every time I fill up. If I shut the CEL off as soon as it goes on, it does not come on again until I fuel up. I can't find anything else.

 
if fillup is triggering the code, look for issues with tank venting. pressure from filling tank has gotta get out someplace...air venting out of tank is sposed to go thru charcoal canister to filter gas fumes out of atmosphere. if vent tubing is bad or canister is plugged or canister tubing/connex are bad, this could trigger the dread PO457

 
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