ss4chad

iTrader: (26)

So my wife's car has the P0455 code for emissions. I have changed the gas cap, the EVAP Solenoid and the EVAP Canister. But the code remains. It even says that the code is 'Permanent" when you hook up a scanner.

What am I missing? What component has failed and/or is continually failing that gives the code and will not go away? Need help here, inspection is coming due soon and it wont pass.

How can I test the system to see what is wrong instead of just throwing parts at it?

Chad

jmilz28

iTrader: (13)

Silly Q but, did you clear the code after the last repair? If not, clear it, you may have gotten it. If so, you've still got electrical to troubleshoot as well as tank and lines. May be worth an hour at a reputable shop to troubleshoot and decide what to do from there...

ss4chad

iTrader: (26)

Yes I reset it with the OBDII scan tool. It still says it has a 'Permanent" fault (P0455) that wont go away. After about a hundred miles, the engine light comes on again.

Chad

Ls1Ryan2002

Have you checked for any gas leaks at all? Only thing I can think of would be clearing the code and unplugging the battery for 30 mins to see if the car will completely reset itself. It seems you have covered any and all reasons as to why it would leak. Only thing I could think of is the tank leaking or something along those lines. I'd try the clear code and 30 min battery disconnect and see if it goes away.

08-4door

iTrader: (5)

My 2016 Silverado just starting throwing the same code after I switched to e85

ss4chad

iTrader: (26)

Unhooked the battery as well each time I changed a component.

Funny thing 08-4door, I started running the e-85 in the car as well to take advantage of the cheaper price per gallon. I've been running GAS in it now for about 3 weeks straight to see if that has anything to do with it.

I will check for gas leaks to see if a hose has deteriorated or something else, wish I could pressurize the tank and lines somehow, might be a better way to find a leak.

Chad

Ls1Ryan2002

Odd that it's still throwing that code even after what you've replaced/tried. I'm curious to see what could be causing this.

blk90coupe

iTrader: (1)

Smoke test your evap system to check for leaks. Probably a leaky vent hose.

ss4chad

iTrader: (26)

Ok, how would I do that? What tools would I need? I'm creative and could fab up something, what would that something be? Give me some ideas.

Thanks!

Chad

blk90coupe

iTrader: (1)

Need a smoke machine

00pooterSS

iTrader: (40)

Don't worry about the "permanent" part. That just means it's failed consecutively on two trips, otherwise it would be labeled "pending".

When I have to diag a 455 on a GM I usually find these things, listed in order of most common first (also we have had to go to dealer only evap parts with GM cars, the aftermarket parts fail quickly)

1. Purge Valve intermittently not sealing or stuck open (valve at engine)

2. Stuck open Vent Valve (valve in rear of car near tank or on canister)

3. Stuck Fuel Tank Pressure Sensor. It's on the fuel pump, on top, and looks exactly like a map sensor, sometimes they get stuck and the system then thinks it has a large leak since it doesn't see a pressure change during testing.

4. Gas cap bad/loose/missing


A smoke machine is a big help with evap but only if you have a leak. To test your evap valves grab a rubber hose, I most commonly use 5/16" for the purge valve and 5/8" for the vent valve..

With the key OFF disconnect one of the hoses at the Purge valve (valve at the engine) and connect rubber hose to the nipple, suck on the hose and seal it with your tongue, see if it holds vacuum, try to blow through it also, it should not leak AT ALL. If it leaks any even the slightest bit it's bad. I have to try them multiple times sometimes as a lot of them stick open intermittently. So go turn the key on and crank the engine then turn it off and repeat the suck/blow test.

Next try the Vent Valve (valve by the tank) with the key OFF the valve should be open, with the key ON the valve closes and seals. Do the same thing as above but with the key ON and check for leaks.

I really never find leaks on GM stuff, unless it's pretty old and someone has been doing half *** work on it.


USE ONLY DEALER PARTS!! we have lots of failures with aftermarket evap stuff for GM and we have lots of bad gas caps come through that are aftermarket on all makes of cars.

5w20

iTrader: (21)

Pics of turbo notch

ss4chad

iTrader: (26)

That's awesome man, thanks!

Chad

ss4chad

iTrader: (26)

I haven't replaced the Fuel Tank Pressure Sensor. All others have new parts.

Chad

00pooterSS

iTrader: (40)

One thing i've learned in 19 years being a tech, being new DOES NOT guarantee the part is good. You'll still need to check. I've replaced those very valves with aftermarket parts to have them fail less than a week later. Some bad right out of the box. If they aren't dealer parts, return them and put dealer parts on. Not for all repairs, just the evap valves and fuel cap in this case, had many of the aftermarket brands fail very quick, even the OEM stuff isn't that great, but it's the best option you/we have.

Also, if you check them again the way I posted you can confirm your electrical connections are good etc.

You'll need to get into the datastream and monitor the fuel tank pressure to confirm it's the pressure sensor. If you want to just try it go for it, but it's usually sold with the pump and those are roughly $300.

ss4chad

iTrader: (26)

I agree 100%, new parts are sometimes bad from the factory, had that situation on cars and airplanes many times.

As soon as I get the truck back on the road I am going to do the things you suggested. Thanks for the help!

Speaking of truck issues, can I run new braided ss hose straight from the tank to my FPR. Install a fuel filter in their somewhere of course but, can I just rip out the three lines going to the motor (supply-return-evap) and replace the supply and return with SS braided line? I will tune out the evap. Is there anything I should be concerned about anywhere in that plan? Some special box or sensor that records fuel density or pressure or fuel supply temp, fuel return specific gravity or gas pedal pressure as it relates to EGT? I'm being facetious of course.

Thanks again for the Impala help!

Chad

00pooterSS

iTrader: (40)

No problem man, as for the SS lines in the truck, you can do whatever you want as long as you have enough money lol.

I would say go for the SS lines but talk to your tuner about removing the evap, I was going to do the same once and he said leave the evap, removing it sometimes causes issues. He builds high power cars and has a hell of a reputation so I didn't ask what the problems were, I just said okay and left it.

ss4chad

iTrader: (26)

One of the reasons I am deleting the EVAP is because I will be installing a Vic Jr with a Gold Blade ETB. I have no place for the EVAP plug in the intake, don't have one for the MAF sensor either but I'm drilling one for it.

Chad