Engine Code po455 Still runs good

rdsrds123 · Mar 31, 2016

Hello there, I have a 2007 4 cylinder 5-speed. Just a few minutes ago the check engine light came on, and I took it to Advance Auto to find the engine code. They tell me it's po455. This includes evaporation emissions system, fuel filter, and air filter. The dude at AO said it was probably the fuel filter@145000 miles. I replaced the air filter last year.

Seen this code before? Any ideas before I start throwing parts at it?

thanks guys!

adsm08 · Mar 31, 2016

Wow, that guy's lack of a clue is embarrassing.

P0455 is a gross evap leak/no flow code. Because of the way the system determines a leak it can't really tell the difference between a huge leak or the system not allowing proper flow. The air and fuel filters shouldn't even be on the radar at this point as they are parts of altogether different systems. (For those who care the argue about the fuel filter, it is part of the liquid fuel delivery system, P0455 pertains to the evaporative vapor control system. By the time liquid fuel is in the evap system there are other issues)

There are four main things that can cause this code.

1) A bad or missing fuel cap.

2) A damaged or disconnected evap line.

3) The canister purge valve has failed or open or close.

4) The canister vent valve has done the same.

rdsrds123 · Mar 31, 2016

Thanks for getting back so quickly. I searched po455 and got about the same, but they also say the fuel filler may be bad and the tank needs to be dropped. Not so on this year? I looked at the tool that AO guy was using and it was the tool that said air or fuel filter, in addition to emissions. I too thought that wrong for the same reason.

When I check those four items you outlined, will it be obvious? Is there a way to check the switch that opens and closes the lines?

adsm08 · Mar 31, 2016

The fuel filler could be at fault. Basically what the code means is that when the system sits it isn't building any pressure from fuel evaporating (a leak) or when it tries to purge it doesn't see the pressure drop at all. A bad filler can cause that.

The two valves can be tested by jumping power and ground to them and seeing if you can blow through them.

The leak may not be visually detectable. A bad gas cap can't be see visually. A hole as small as .055 inches in one of the lines can cause this code as well. You aren't going to see that with the naked eye. Evap issues usually require special equipment to test properly, namely a scanner that can command the valves and a smoke machine so you can fill the system with something that can be seen when it leaks out.

If you are feeling really adventurous you could plug up the lines at each end, wait a few hours for some pressure to build and follow the evap lines with a lighter. You will probably find out if you get near fuel vapor.

rdsrds123 · Mar 31, 2016

Thanks again! That was rather spot on. I'm going to remove and jumpper the two valves first. If they're not good, I'll take a pilgrimage to Crazy Rays Junkyard and buy a used valve or even a gas cap...yeah, I'm cheap.

RonD · Mar 31, 2016

Fuel filter would be a stretch..............in anybodies book.

P0455 basically means the fuel tank is not able to hold pressure anymore.
Obviously if gas cap was off or wasn't sealing you get that code.
If filler/vent hose has a crack you would get that code.
Then you have the hoses at the top of the tank, fuel line and the EVAP hoses.

Why not do this, get a friend and a short piece of garden hose, or any hose really, lol.

Remove gas cap and put hose in the tank, just a little, seal around the hose, rag/towel what ever, then blow into the hose.
Have a friend listening for where the air is getting out.
Also pop the hood and listen on the passenger side of engine towards the front and at the intake, bad solenoid leaves tank hose open all the way to the intake.
If tank seems to hold pressure then gas cap is bad.

Yes, I am cheap too

You really don't want to use an air compressor for this, human lungs can generate about 2psi of pressure, which can't hurt any connection on this system, air compressor can do a little higher pressure, lol, which can blow off connectors.

Do test with key off, key on, and then key off but just after shutting engine off

enjr44 · Mar 31, 2016

I am also cheap; but, before I got carried away, I'd try a new fuel cap. Probably not that simple.

With my 02 it took the equipment Adsm08 mentioned to determine the canister was the problem.

rdsrds123 · Mar 31, 2016

It was the first thing I checked(because it was easy)--da gas cap! Oh well, false alarm...

Engine Code po455 Still runs good

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