Ok, I've been chasing down a P0455 CEL for about a month now. Yeah, I know what they are, I've been hunting down a leak in the evap system. I've found one vacuum line leak (looks like the line that feeds the solenoid, and one on the canister line, hopefully thats all.

The problem is that each time I find something, I clear the codes (cheapo walmart ODB scanner) and wait till it comes back. This may take several days because most of my trips are short, and it seems to take several long trips to set it. From what I read, its because of the timing of checking.

After the last leak, I cleared the codes, and it has been fine for about 4 days, but I hooked up the scanner on a whim, and there were the P0455 and P0442, but the CEL was not lit.

Is that from before, and I just didn't get them cleared right, or are they in there because the leak is there, but not confirmed yet?

I also have a leaky plenum too, got the kit, but haven't had time for that yet, could it cause problems too by lack of vacuum?

 

The codes you read may have been 'pending', and won't set the CEL. (i think...)

check the fat hose that goes from the canister, to the intake. Probably has dry rotted somewhere.

 

i've had the same problem for months and months.
i've replaced the gas cap and the purge solenoid.
i've cut the hard ends off most all the hoses...
sob is still on.

mine also takes about 4 or 5 days to come on. i think it gives it the benefit of the doubt before setting the light.

you can check the codes by doing the key dance - on off on off on.
you can clear all codes by disconnecting neg batt cable and turning on headlights for 30 sec. key dance will confirm codes are cleared.

if you find yours let me know.... good luck.

 

I had the same exact codes. Went searching and sure enough one of the hoses at the canister was cracked. Threw on a new hose and clamps and good as new. GL

 

Just got mine solved last week. Just like hey suggests, follow the large hose all the way back to the canisters, making sure it has no cracks at any of the joints. Mine leaked at every fitting. I dropped the canisters below the passenger side and the hose was cracked at both ends under the hose clamps. Cut off the ends and fastened back down and now my leaks are solved.