Question about P0455 code, why isn't it in my shop manual.

NickD

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First time the CEL came on, was south of town at the airport, also a Chevy dealer across the street, but at 2:00PM Friday, all their cars were gone and they were closed. Found out later they moved all their cars to our mall north of town trying to sell them.

I drove north to our Buick dealer, wanted 30 bucks to scan it, but business was so slow, they sent their mechanics home, but I agreed to pay that, much cheaper than buying a scanner. Advanced Auto was another couple of blocks north, stopped there, heard they gave free scans, they do. Used an Actron, a yellow thing with about 4-5 buttons on, KOEO, read a P0455 code, kid asked me if he should reset it, said yes. Evaporative system leak also was on the screen. Wrote that down and double checked it. As my gauge was close to E, filled up with ethanol free on my 04 Cavalier sports couple, first time the CEL ever came on.

When I got home, dug out my shop manual, looked everywhere in the some odd 3,000 pages, found a P0453 code and a hundred more, but no P0455. Did a net search on P0455 with over 4,000 hits. Sure a lot of people giving advice on the web that don't know nothing.

Buick dealer told me those CEL are popping on all the time, as long as the car is running fine, don't worry about it, a couple of weeks ago, it popped on, on my 92 DeVille, told me EGR valve problems, has the self diagnostics, pulled the EGR valve out, it was carbon stuck in the closed position, that would cause major engine problems. Probably why I call it a HAL light instead, a heart attack lamp. Did a lot of chasing around yesterday in the Cavalier, CEL never came back on, yep, my gas cap is on tight with a good seal.

Some 400 pages in the shop manual, all here headed by some error code, except the evaporative system, not a code anywhere in that section, only has two electrical devices, a Fuel Tank Pressure sensor with a plus or minus 1"/Hg range and a vent valve, solenoid operated. That low vacuum explained to me why I never heard a strong in rush of air when I remove the gas gap like in the DeVille, DeVille darn near sucks me in when I remove the cap. With the FPT sensor, could be a bad sensor or a leak, but have to remove the tank to check that sensor.

Can only wonder if the GM TECH II scanner would also show that P0455 code, but won't know unless the CEL comes on again, but then, why isn't it in the manual?

Wife and I did go to the mall yesterday, was greeted by a salesman, said with our GM card, we could get 9,000 bucks off anything in the lot, over 200 cars there. We couldn't find anything we even came close to liking, wife said the best car there is our Cavalier, I agreed. Besides us, only one other couple was there looking, no wonder why GM went bankrupt, they don't ask neither what their dealers nor customers want. Their CEO lies like hell when he says they produce vehicles that the people want. He sent me a letter last Thursday with an additional $1,000.00 off, if that is true, we could get a new Aveo for 4,000 bucks. Told my wife, maybe we should try to buy it and see if we can sell it for $5,000.00. But she said, she didn't want that ugly thing sitting in our driveway.
 

oldtimer53

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P0455 is evaporative emissions gross leak detected. It can be caused by a loose fuel cap or any number of improperly sealing components. There is a on demand self test, but most scan only devices can't initiate it.
The normal test is done during the drive cycle, but won't happen unless the tank is between 1/4 and 3/4.
I'm more of a FFFFord guy so I can't help with the specifics of the tests, but inspect the charcoal canister where various check valves and solenoids grommet seal to it.
 

Gus

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Unless you can see damage to a component, and the gas cap and fill pipe is ok, more often than not the problem is a vent solenoid.....

However, the only way to know for sure is with a smoke test, and sealing the system with a Tech II.....

"Buick dealer told me those CEL are popping on all the time, as long as the car is running fine, don't worry about it, ".....if he told you that, he's an idiot!

If you could get $9K off a car, then you're an idiot! Hard to believe they had nothing better looking than your crappy '04 Cavalier! ;D
 

NickD

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Wife told me to get that 9 grand off in writing, would have done that anyway, but did talk it off, Ididn't too much of that service managers comment either, went 57K miles without a CEL problem, something is wrong.

Finally found the evaporative codes in the manual, the hard way, only the codes were listed, a bunch of them, no description, but by thumbing through some 40 pages, found all the codes, four of them that deal with the evaporative system.



Evaporative system has only few parts, the fuel tank with a vent hose, a carbon filled canister with three ports on it, a vent valve between the clean end of the canister and the atmosphere, it purpose is to reduce fuel tank pressure, a purge valve located between the intake manifold and the canister that returns fumes back to the engine, and that fuel tank pressure sensor that monitors is positive of negative pressure in the fuel tank.

In terms of leaks, gas cap, filler, vent tube, either of the two valves, or even in the feed and return fuel lines, but those would drip raw gas.

Sounds like the PCM is bored and looking for something to do, testing the evaporative system is one of those.

Large Leak Test

P0440 is set if with the vent closed and the purge opened, PCM does this, that will vacuum the system. FTP monitors the time it takes to reach a predetermined vacuum with a predetermined time period, if not, this code is set. You have a large leak! Of course the manual does not specify neither the vacuum or time period, wants you to guess at these two very important numbers.

Small Lead Test.

P0442 is set after the above test with both valves closed to monitor the decay time of the vacuum again over a predetermined time period, if it drops too quick, this code is set. Gather if you found and repaired a large leak, would also have to find a small leak as well, but seems even with a large leak, both codes would be set.

Canister Vent Restriction Test

P0446 is set if when the PCM opens the purge valve, the tank vacuum does not decay at a predetermined rate over a given time period indicating that the fumes cannot pass through the canister. A procedure if given to blow out the canister with a 15 second liquid nitrogen blast, if that doesn't work, get a second mortgage on your home.

Purge Valve Leak test.

P1441 is set if when the PCM closes both the purge and vent valves, recall the purge goes directly into intake manifold vacuum, if the vacuum increases at this time, again a predetermined amount in a predetermined time period, this code is set. Assuming the purge valve is not completely closed, causing an increase rather than a decrease in tank vacuum.

Again that P0445 code is not listed anywhere, this has to say something about aftermarket scanners.

I only got as far as testing out the purge valve, hit the intake side with 27"/Hg, it held steady and dropped instantly when I hit the solenoid with 12 volts. I did note a rather loose canister coupling, coated that with non-hardening Permatex. Also has a test port on it, could attempt to draw a small vacuum on that port and see what happens. The canister port disappears under the vehicle chassis, 8 month old granddaughter showed up, that dropped the car routine for today

I believe if the vacuum does not hold, can hit that port with a couple of PSI and hand feel for leaks.

Treat a quarter full tank as an empty tank to prolong the fuel pump life, suppose I could also treat a three quarter full tank as an empty tank to keep that CEL off.
 

Gus

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Nick, since this is a large leak, if you tried to pull a vac with a hand pump, you couldn't pump it fast enough......another thing is, you need 12 volts to the vent solenoid, to keep it closed......you need zero volts to the purge solenoid to keep it closed(just disconnect it)....
 

NickD

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Probably a good idea they keep that vent valve opened all the time with the engine off, with the heat of the sun in a sealed system, the gas tank would blow up. CEL never came back on since Friday, was backing up on a narrow swamp road for airport maintenance and almost killed the engine. First thought was a misfire code. Another guy told me my purge valve solenoid is shorted. Only pulled 200 ma at 12 volts. Thought with OBD II, standard codes were used, about as standard as our taxing system.

Did go back to that Chevy dealer, with my GM card, would have to buy a new Suburban to get $9K off, but was looking at an Aveo, would only get $5.2K off, still seemed overpriced at that. Now if I purchased a used 2008 Suburban with 12K miles on it, they won't take the GM card on that, could get $20K off the original price. I took that to mean, with my GM card and buying that new Suburban with those rebates, I would only lose $11,000 the first year, instead of $20,000.00. Seems to be quite the bargain. Should I take it?

Think I would take that Aveo, if they threw in a Tech II scanner as part of the deal.
 

NickD

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Another week goes by, lots of driving this week CEL never came on again. I never got under the car either. Maybe that Buick service manager is right, they pop on for no reason.
 

Gus

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Maybe you left your gas cap off, and then put it on......By the way, most Service managers only know what their techs tell them....good tech wouldn't say that.....
 

NickD

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I could have a loose wire, either in the vehicle or in my brain, if I removed the gas cap while driving when the CEL came on, that loose wire is definitely in my brain. But that CEL never came back on again. Ever feel like the whole world is caving in with just too many projects going on at the same time?
 
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