CEL Code 455 and 496 - Chevy Cobalt Forum / Cobalt Reviews / Cobalt SS / Cobalt Parts
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post #1 of 3 (permalink) Old 04-12-2010, 05:25 PM
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CEL Code 455 and 496

Since last feb. when I got gas siphoned out of my tank my CEL has been coming on and usually staying on. The codes has been the following:

PO455: EVAP System Leak
PO496: EVAP High Purge Flow

My MPG has gone down some. I went from mid 30's to upper 20's.

Any ideas as to what the problem is??? I've put on about 5000 - 7000 miles since then... And at times after getting gas the car runs ruff after starting. But this is only a 1 out of 20 things that happens.

I have installed a new fuel filter and AC Delco spark plugs at 70,000 miles before this all happened.

Also, yes I get the Check gas cap msg, but I have since then bought a new locking gas cap ans still get this msg.

Last edited by jim2029; 04-12-2010 at 05:27 PM. Reason: more info
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post #2 of 3 (permalink) Old 04-12-2010, 05:38 PM
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PO455: EVAP System Leak = BAD gas cap.... replace it.

PO496: EVAP High Purge Flow

The highlighted part in this pic is the purge solenoid valve.

The highlighed in this pic is the evap canister and the can's vent valve.

The only routing of the evap system i can come up with is this crazy pic from SI.

Hope it helps

Here is this thread for reference too >>> https://www.yourcobalt.com/forums/eng...res-valve.html

Last edited by XFE; 04-12-2010 at 05:45 PM.
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post #3 of 3 (permalink) Old 04-12-2010, 05:46 PM
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I got the 455 before replacing the gas cap. Bad cap??? Or are the locking caps junk?
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cel , engine , evap , gas , ruff

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