Can someone explain to me what this does and why? It looks like it recirculates fuel vapor back into the intake, but I'm not sure why. Is it hooked up basically to a vent on the tank?

 

It limits fuel system vapors from escaping into the atmosphere. Fuel tank vapors are allowed to move from the fuel tank, due to pressure in the tank through the vapor pipe, into the EVAP canister, Carbon in the canister absorbs and stores the fuel vapors. Excess pressure is vented through the vent line and the EVAP vent solenoid to the atmosphere. The EVAP canister stores the fuel vapors until the engine is able to use the vapors. At an appropriate time, the PCM will command the EVAP vent purge valve open, allowing engine vacuum to be applied to the EVAP canister. With the EVAP vent valve open, fresh air will be drawn through the valve and vent line to the line to the EVAP canister. Fresh air is drawn through the canister, pullling fuel vapors from the carbon. The air/fuel vapor mixture continues through the EVAP purge pipe and EVAP purge valve into the intake manifold to be consumed during normal combustion. The EVAP system requires the PCM be able to detect a leak as small as 1 mm (0.040 inch) in the EVAP system. The PCM uses several test to determine if the EVAP system is sealed. Such as Weak vacuum test DTC P0440, vacuum decay test P0442, canister vent restriction test P0446 and purge valve leak test P1441.

Hope this helps!

 

I have been getting a P1441 code as well. Looking at what is posted above it sounds to me that there is a leak in the EVAP system some where. Is there any one here that has any experience in diagnosing this or any ideas on what to look for?

Tom

 

Anyone?

 

I was getting that code when the line from the gas tank to the evap canister was blocked. Actually it was not blocked but melted closed when my rollcage was installed. Once that was found and replaced the code was no longer thrown.

Keith

 

I've been told anything from a loose gas cap to fueling the car while the engine is off and the key turned on can cause a code.

 

That would cause the code to be thrown also. The basic problem is that pressure is not building up in the evap soleniod.

Keith

 

Ok, here is an update on my situation. I have also been getting a LH fuel level sensor code (P1432) and a CAGS code P0803) and an ASR torque (P1571) along with the EVAP code (P1441). When I first bought my car one of the first things I did was to install a Mid America skip shif eliminator. Well after getting the CAGS code I removed the eliminator and plugged the harness back into the tranny. After the first drive I still got all four codes. When I started it up the second time I had NO check engine light! I checked for codes and all I had was the P1432 code all other codes are gone. After 6 or so restarts none of the other three have come back. When I got home last night I looked at the skip shift eliminator the end of the harness was MELTED and the resistor that is inside was burned and gone. Some how that must have been creating havoc for the computers and setting codes.

Tom