P0440, p0441, p0446
- Thread starter Aelfwine
- Start date
Register to hide this ad
BlackWorksInc
New member
I would see if you can find information in the FSM for testing the Purge & Vent solenoids. It probably wouldn't hurt to check the gas cap, though the P0446 (and lack of a P0455) makes me think its unlikely this is the cause.
The DTCs are as follows:
P0440- Evaporative Emission Control System Malfunction (A generic DTC indicating that there is an issue in the EVAP system)
P0441- Evaporative Emission Control System Incorrect Purge Flow
P0446- Evaporative Emission Control System Vent Control Circuit Malfunction
EatonKyleH
New member
In short this is probably one you will want to take to have diagnosed unless you have a scan tool with appropriate bi-directional controls, a smoke machine and some pretty good EVAP system knowledge.
It is fairly common for a failed Charcoal Canister to cause these 3 codes to set at once but there are several other things such as the fuel cap, evap lines, the filler neck, and so on that could also cause each. Enough variables come into play that I would not recommend replacing anything (other than possibly the filler cap as a try) without proper diagnosis.
Below is some simplified testing I pulled from archives at work that show the same complaint.
Customer Concern:
Engine runs, but the Malfunction Indicator Light (MIL) is on with codes P0440, P0441 and P0446.
Average Reported Mileage:
115511
Tests/Procedures:
1. Verify that the Vacuum Switching Valve (VSV) for the pressure sensor (located on the canister) operates correctly. This is a normally closed (N.C.) valve. When energized, it should open. When de-energized, an internal spring should close the valve.
2. Verify that the canister closed valve (located on the air filter housing) closes and does not stick closed when operated. This is a normally open (N.O.) valve. When it is grounded, it closes, and it should never stick closed.
3. If both solenoids operate correctly and are not sticking, inspect for a restriction in the Evaporative Emission (EVAP) lines that could affect how the canister vents after a leak test is performed.
4. Verify that the fuel cap is a factory part. If the fuel cap leaks or does not hold the correct amount of vacuum when the system checks for a leak, all the codes will set.
Tech Tips:
If possible, use a scan tool to turn these two solenoids on and off. This is a good way to test the operation of the internal drivers of the Engine Control Module (ECM) and the wiring harness. Refer to Toyota TSB #EG005-01 and #EG013-03 for additional information on the EVAP system operation.
Best of luck to you and hope this helps you make a good decision on what to do.
TheDurk
Elite Member
Relevant chapters attached. Access the whole thing here:
1996 to 2002 Toyota 4Runner OEM Repair and Wiring Manuals
TakeitApart
New member
In my experience, most likely the evap. vent valve is stuck and not working. You'll get the P0440 (generic malfunction code), the P0441 (because the pressure sensor doesn't see a change when the purge valve activates, due to the vent valve being stuck and likely little to no pressure in the evap. canister.) and finally the P0446, because of the stuck vent valve.
I use the toyota techstream to active test the vent valve, then I unplug the valve's connector and slide a 194 bulb into the terminals of the harness plug, active test the vent valve on, then look for the light to light up, telling me that the command is working and that the circuit is getting power and ground. From there, I'll active test the purge valve and check that it bleeds pressure when active, and holds it when off.
EDIT: I'm not sure about the 4runner, but most other models have a serviceable vent valve, meaning you can buy just the valve. beware though; the screws that hold it probably won't come out!
I use the toyota techstream to active test the vent valve, then I unplug the valve's connector and slide a 194 bulb into the terminals of the harness plug, active test the vent valve on, then look for the light to light up, telling me that the command is working and that the circuit is getting power and ground. From there, I'll active test the purge valve and check that it bleeds pressure when active, and holds it when off.
EDIT: I'm not sure about the 4runner, but most other models have a serviceable vent valve, meaning you can buy just the valve. beware though; the screws that hold it probably won't come out!
EatonKyleH
New member
Just to add to the above.
The vent valve on the 3rd gen 4Runner is only available with the charcoal canister (you get both when buying the canister and as it is attached)
Last I checked it was not available separately from the canister on this model.
The vent valve on the 3rd gen 4Runner is only available with the charcoal canister (you get both when buying the canister and as it is attached)
Last I checked it was not available separately from the canister on this model.
Aelfwine
New member
So the codes came back today after 200km. I smell gasoline from the gas cap area after I just drove. Took a look at the gas cap and found something strange. Looks like somebody JB welded a crack or something. Here is a pic.
Also my vsc/track off lights are on. I think I've read somewhere that they have something in common... I might be wrong though.
Let me know what you think.
Also my vsc/track off lights are on. I think I've read somewhere that they have something in common... I might be wrong though.
Let me know what you think.
EatonKyleH
New member
Could indeed be your issue. Hard to say without any testing but highly possible being that you can smell fuel badly. And yes the vsc/trac lights come on when a code is stored.
Last edited:
