P0441 and P0455 OBD Codes

So this morning I got these two codes for the first time ever:

P0441 - EVAPORATIVE EMISSION CONTROL SYSTEM INCORRECT PURGE FLOW

and

P0455 - EVAPORATIVE EMISSION CONTROL SYSTEM LEAK DETECTED (GROSS LEAK)

Any idea what these codes mean and how to troubleshoot/repair?

Thanks.

Rick

 

Most often it's a leak somewhere in the EVAP system.

Check your gas cap first, make sure the seal on it is good and it's on tight

 

Will do, thanks!

 

Gas cap is tight. Codes keep coming on and off…. Any help would be appreciated.

 

Hello -

You have a leak in your Evaporative Emissions Control System. aka your EVAP system

This system, in simple terms, draws the fuel vapors that exist in your gas tank into the engine via the engine's vacuum (sucking of air). This is EPA required equipment in all 50 states to reduce what is called fugitive emissions.

Key points:
In order for fuel vapors, which would otherwise eventually leak to atmosphere, to be pulled all the way from the gas tank into the engine, all the EVAP system hoses and pieces must be totally sealed and "bubble tight" which is an expression for 100% leak free. You cannot suck your margarita from a straw with a big split in it and the idea here is the same.

As mentioned above, the gas cap must be tight and sealed. There should be a actual gasket on the underside that isn't cracked or torn or missing. It should also be free of grit and grime. Just because it can screw tight does not mean it is leak-free. Because gas caps get unscrewed and screwed back on again so many times, this is often a primary cause of these codes. RECHECK YOUR GAS CAP. Because they are so cheap, I am OK with just arbitrarily replacing it.

There are multiple other EVAP system leak sources that you must inspect for.

Where the gasoline fill tube stabs into the gas tank, that fill tube is sealed with a big rubber grommet. Depending on your winter conditions, that grommet could be failed. Or your fill tube corroded. The top of the fuel tank, where it houses the fuel pump and fuel level sending unit and vapor pressure sensor could be leaking. Quite common.

There is a charcoal canister filter inline between the tank and the engine that is intended to absorb actual liquid fuel and prevent that liquid from slugging into your engine instead of just vapors. It is in a plastic housing and that could be cracked.

Any of the EVAP system hoses could have a hole or split in them or be leaking at a hose clamp.

Last but not least, right near the engine, there is an EVAP purge control valve that is computer controlled and continuously adjusts the amount of vacuum in the gas tank based upon the gas tank vapor pressure sensor (see above).

All of these are leak sources which must be carefully inspected.
--------------------

If this is not your proverbial cup of tea in terms of troubleshooting, simply take your Taco to any shop near home. Describe to them the two codes you discovered and ask them to perform a visual inspection followed by a "smoke test".

You can expect to pay a 1 hr minimum diagnostic charge, which is standard. It will take them <5 minutes to get your Taco in a stall and verify your codes. Then another 20-30 minutes probing around with the hood up and with a good light. If the visual inspection has not yet revealed your vacuum leak, they will rack your truck on a lift and use a machine that generates super small amounts of positive pressure (like ounces per square inch, not pounds per square inch) while also filling your EVAP system up with a harmless but visible smoke to identify the leak.

Any competent shop will have diagnosed dozens of these if not hundreds before on Tacos, ForeRunners, Camrys, Corollas, Tundras, etc.... At most, you can expect to py 1.5 -2 hrs of total shop labor and then factor in replacement parts plus labor time to replace them. The only really expensive piece is the charcoal canister if that has failed. Likewise, if the leak is from the top of your gas tank, expect to pay an additional 2-2.5 hrs of labor to drop the tank and fix the issue(s) there and re-install it. It is not difficult, just tedious.

Should you decide to opt for taking it to a shop, bring your truck as near as possible to empty on fuel as possible. It makes the work there a lot easier.

HTH
Andy

 

Wow! Thank you very much Andy. I will take a look at everything you mentioned and if I can’t figure it out look for shops around me. The stealership is out of the question.

BTW, what issues, damage will this cause if I don’t care to much to fix it right away or make it a priority?

I mean, emissions? I don’t leave in The People’s Republic of Kalifornia or anywhere where I need to pass emissions/State inspection…

Could I just roll with it throwing the code(s) out every now and then??

 

Here is my feedback:

1) You will eventually experience, if not already, diminished drivability and poor fuel economy. With any vacuum leak (too much air) as detected by the O2 sensors, the engine computer is going to start adding fuel for no good reason. Rough idle, hard starting, and more will be your symptoms and you will eventually also throw O2 sensor codes.

The worst thing about an unmetered vacuum leak is the added fuel by the engine computer. This extra, unburnt fuel, can and will foul your catalytic converters which are NOT cheap to replace when they plug up.

2) You should get it fixed. Sooner, rather than later. One, it is not expensive all things considered. Two, I never ever never never ever recommend driving around with a Check Engine Light (CEL) lit or even flickering because it makes one disregard a CEL when it *really* matters like a low oil level or high coolant temp which can destroy an engine in minutes.

Do the right thing. It is like a tee tiny cavity, easily fixed where you enjoy the hot dental tech and the nitrous oxide, versus what is going to deteriorate into a PITA proverbial root canal with Nurse Ratchet and that f**king smell when they drill out your entire tooth and it actually hurts.

My two cents

 

Just note the EVAP monitor is not a continuous monitor, the leak monitor runs 5-8 hrs after the truck is turned off and can last up to 30 min.

Check the seal on the gas cap and make sure it's good and not cracked or dry rotted, I'm assuming it's an OE cap and not and aftermarket locking one?

You can also check the purge valve on the left side of the engine to make sure it's not stuck open, unplug the hose and electrical connector from the valve and make sure no vacuum is present at the port with the engine running.

If that's all good and you can find no issues with any of the hoses with a visual inspection you will need to smoke test the system to find where it's leaking just not the vent line must be plugged at the charcoal canister/leak detection pump during this test or you will have a false positive.

 

Not gona hurt anything running awhile (aside from not knowing if any other codes pop up) providing you have no raw fuel leaks but it would be a good idea to get it fixed , hopefully you can find it yourself or find a shop that knows how the Toyota EVAP system works and can diagnose it properly.

 

This seems very common. Having the same issue with the same codes. Got it checked today with the smoke test and Toyota is telling me I need an entire gas tank replacement because the hose comes attached to the gas tank and that’s what needs replaced. Even though they didn’t drop the tank or show me pictures of exactly what was wrong. Nonetheless quoted me at $1600….they also said the purge valve is open. Idk what to do honestly. I’m not paying that much for a whole gas tank replacement.

 

^you^ need to head to an independent shop with this information in hand. Do NOT disclose this information to them except to perhaps say you had someone else look at it and you think the EVAP system leak it is coming from the top of the fuel tank. This is VERY COMMON especially if you live where it snows.

The gas tank RARELY NEEDS to be replaced. It takes <1 hour to lower the gas tank and inspect it and the vacuum hoses and fittings on top of it.

 

Finally had the time and the weather cooperated to troubleshoot the codes. So the f*****g squirrels got me some more. They chew through what seems to be like a return or vent hose??

Can anybody help me in getting the OEM part number?

That is the only issue.


This is where the hose connects, right next to the filler neck



Any help would be appreciated.

Thanks.

 

Is this guy over here, the one in the middle with the square clip:


Here are pics I took with my borescope, this is the other half of the hose, it goes into the back of the tanks. Sorry, they’re pics of the screen of the borescope, not great: