EmmanuelSa

I am stumped. The CEL comes on but goes away when the tank is full. I replaced the gas cap and the air filter. I took it to the lexus dealership, and they told me that all of the tubes looked fine. They ran an emissions test and it all was fine too. They cleared the codes and I left. Not even one mile later the same codes came back.

I think I read somewhere that its possible for a crack in a tube to only break down when the engine exerting a certain amount of torque or something.

Are there any existing threads that can help me figure out why I keep getting these codes?

The car is a 2008 IS250

leoferus

Find a shop that will perform a smoke test on the evap system. The leak can be anywhere between the engine and the evap canister. P0441 indicates that evap canister purge flow is incorrect. So, this can indicate that the purge VSV is malfunctioning, a hose is plugged, clogged, disconnected, and/or leaking. You can have a leak at the canister as well. There are a number of things I check in a specific order when I encounter this code.

If you can recreate the problem your technician should be able to diagnose it. Find someone that knows how to diagnose evap systems properly. Ask for the shop master level, MDT, or foreman.

EmmanuelSa

Thanks! I specifically remember the code coming back on as I revved the engine getting back on the highway. I will make sure the mechanic tries to replicate that during the smoke test.

leoferus

The code setting conditions are specific but your technician must know how to diag. The "test" that they run does not always reveal problems. Someone that likes to diagnose and troubleshoot would know what to do but you need to find such a person. You will also need to tell them you can recreate the condition. Lastly, if it were me diagnosing, I'd ask you to leave the vehicle with me indefinitely. So be prepared to take a loaner, rental, or shuttle home. Us thorough techs don't do "fast food" style service.

While engine running, following conditions are successively met:

• Negative pressure not created in EVAP system when EVAP VSV turned ON (open)
• EVAP system pressure change less than 0.5 kPa (3.75 mmHg) when vent valve turned ON (closed)
• Atmospheric pressure change before and after purge flow monitor less than 0.1 kPa (0.75 mmHg)

Possible problem areas:

• EVAP VSV

• Connector/wire harness(EVAP VSV - ECM)

• Leakage from EVAP line(EVAP VSV - Intake manifold)

• ECM

Rodents can damage wiring and tubing. A good visual inspection can reveal both.

A gas cap is not a likely cause for this code.

EmmanuelSa

Thank you SO MUCH I will pass this along to the mechanic when I take it in. Hopefully the fix isnt too expensive.

EmmanuelSa

UPDATE FOR ANYONE ELSE WITH THIS PROBLEM

It was the VSV. The mechanic test drove the car on three different days to try and replicate the malfunction. The problem was intermittent. Meaning he would hear the "click" noise that the VSV was working. However, on the fourth test-drive he was finally able to observe a vacuum error with the VSV.

It was $260 for parts and labor.