Got a 97 SE, and I pulled four different CEL codes today, which I think indicate two separate problems. The first two were 0903 (EVAP canister vent control valve) and 0705 (EVAP system leak – AKA EVAP control system). I took apart the entire EVAP system to try and understand it. Am I correct that the EVAP vent valve is the powered valve attached to the black charcoal box just behind the rear bumper? The valve appears to be a simple piston type valve whose outlet hose goes to a round canister that vents to the outside (near the bumper). The round canister is simply an empty can with a foam filter on top. I take it this vent valve is completely separate from the white purge control valve that is separated from the black box by tubing?

If this is correct, is there any way to clean this vent valve? It doesn’t look like it can be taken apart…I sprayed some WD40 into the inlet and outlet, so maybe that helped.

Also, think its possible that a malfunction with the vent valve could trigger the 0705 error?


The second group of codes were 0210 (Fuel injection system lean – left bank) and 0303 (Upstream oxygen sensor left bank – AKA heating oxygen sensor).

If my O2 sensor is bad, could this trigger a reduction in the fuel delivery to the left bank of cylinders, which would give me the lean condition error? Or vice versa?

Thanks for any help you can give me.

-James