The following article describes cleaning of Evaporative Emissions system (simply referred to as "EVAP") components, specifically the charcoal/carbon vapor canister, vent solenoid and hoses, in effort to solve a P0442 (small EVAP leak) OBDII ('95+) diagnostic code.
This is a very common issue on aging panthers, as dirt and debris accumulates in the vent outlet line and solenoid prohibiting correct operation.

Problems with the EVAP system venting can also cause difficulty with fuel fillups (repeated shut-offs before filled)

On 1998+ models, the EVAP canister, and canister vent solenoid and line can be found directly under the trunk (large black box) with solenoid vent outlet line leading into passenger frame rail opening
On -1997 models, the canister and solenoid are behind the RH front bumper, with fuel tank vent hose leading back to fuel filler.

This problem is more prevelant with the 1998+ design because of it's location.

The following article was authored by 442freak, and was originally posted in This Thread
Well I've been getting a check engine light with a code P0442. Small leak evap. I, like everyone replaced the gas cap and reset it. Didn't come on for a while, then it did again. Apparently the pcm tells the evap system to do a test depending on how much fuel in the tank, temperature, and other parameters. If it senses a leak, it puts a pending code, does the test again. Then a cel if nothing changes.

Took the vapor canister off, the solenoid, the vent solenoid, and lines. Checked them all and cleaned everything with contact cleaner and compressed air.

The canister solenoid had dirt and debris when I pulled it out. From reading on this subject, most of you just replace it. Upon further inspection of it I noticed the plastic side where the hose slips in is serviceable. With a small flathead screwdriver I took it apart carefully. Was I glad I did. There is a screen with a rubber membrane in there and it was filthy. Debris was keeping the membrane opened and I'm sure this was causing the error code because when the solenoid turned off air was still getting in there because the membrane was stuck in open because of the debris.

Cleaned it all up, and tested it.. wanted to add incase anyone ever runs into this problem..

----Courtesy 442freak

An example of a very dirty vent solenoid causing a P0442 code courtesy Tim835

Edited by dRock96Marquis (01/05/12 02:17 AM)
-Panther info & FAQs-

Former owner of a Grand Marquis with a few mods, Grand Marquis "LSE S/C"