Hello all-
I've been having a problem with the check engine light on my xB. Keeps coming back...P0440, P0441, P0442, & P0446. Does anyone have access to a service manual that you could e-mail or fax me a copy of these codes & their possible causes? Or, is there a spot online I can find the info?

Thanks!!

 

the engine light only means that your engine is warming up, nothing is wrong with the vehicle. it will go on everytime you start the car. it shoul turn off after a minutew or two, longer in the winter

 

I don't see a P0440.

P0441 is "Incorrect Purge Flow in the evaporative emission control system." Probably a leak in the cap or vent system.

P0442 is "Leak Detected (small leak) in the evaporative emission control system."

P0446 is "Vent Control Circuit in the evaporative emissions control system."

All three of these relate to leaks in your fuel venting system.

things to check (same for all three codes):

Cracked, disconnected or blocked vacuum hose.
Fuel cap incorrectly installed, cracked, or otherwise damaged.
Open or short in vapor pressure sensor circuit.
Bad vapor pressure sensor.
Open or short in VSV circuit for EVAP.
Bad VSV for EVAP.
Open or short in VSV circuit for CCV.
Bad VSV for CCV.
Damaged fuel tank.
Damaged charcoal canister.
Cracked fuel tank overfill check valve.
ECM.

Sounds like you need to take your car to the dealer for a diagnostic session unless you have messed with the plumbing.

George

 

yes he is right theres not one :?

 

Make sure your gas cap is on TIGHT.

 

Ok...I have had it in to two different dealers, they have replaced the:
1st time: charcoal canister
2nd time: various evap hoses
3rd time: fuel filler cap
4th time: P0440, they insisted a loose gas cap is the only possible cause, and charged me a diagnostic fee.

I KNOW the cap is tight...there must be something else going on. Two different dealers have told me it was a p0440 code...odd that its not listed in the shop manual.

 

If your car has a history of setting the CEL they should not have charged you a diagnostic fee. You have an ongoing problem with the emissions system and it is up to them to resolve it. Just because their "replace parts until the codes go away" strategy hasn't worked so far is no reason to charge you.

It might be a good idea to check into your state's "lemon law". Usually the dealer only gets a certain number of tries to fix a problem (and the CEL _is_ a problem in itself, since you cannot pass a smog check with the light illuminated) and then the customer has certain legal recourses. They can't just blow you off by saying that the gas cap is loose every time. If you take your car in, armed with the lemon law knowledge, it might prompt them to work more diligently in resolving the problem.

All of these codes relate to a self-test of the fuel vent system. Essentially, the ECM closes a valve (VSV for CCV) that normally vents the tank to the charcoal canister and then opens a valve (VSV for EVAP) that applies vacuum from the manifold through a line to the gas tank, reducing the pressure in the tank. The VSV for EVAP valve then closes, and the ECM monitors the fuel tank pressure with a sensor. If the pressure increases too rapidly this is interpreted as a leak and a code is set. The ECM then opens the VSV for CCV valve to allow the vent system to operate normally.

The P0441 code is set if the VSV for EVAP valve fails to either close or open properly.

The P0442 code is set if both valves work properly, but a pressure increase during the test indicates a leak in the EVAP system.

The P0446 code is set if the VSV for CCV valve fails to either close or open properly.

All of these processes interact, so multiple codes are likely. For example, a leak in the system could prevent a pressure drop from being sensed at the tank, causing the P0441 code to be set even if the VSV for EVAP valve is OK.

There are 34 pages of diagnostics related to these codes, so tracking this problem down is more than a notion. However, the Toyota procedure is logical and will likely resolve the issue if the technician takes the time to carry it through from beginning to end. Ask the service writer for his most patient technician!

George