P0443 still haunting me today. =D | Ford Explorer Forums - Serious Explorations

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P0443 still haunting me today. =D


New Member
August 22, 2012
Reaction score
City, State
South Carolina
Year, Model & Trim Level
1997 Ford Explorer
Ive tried cleaning the vent valve and canister, I replaced the purge valve soleniod with a new one from MotoCraft. I changed the wiring connector to the solenoid, and for a few miles the light went away on its own, Now its back, Im out of ideas. To the experts, PLEASE HELP! LOL. Thanks guys.

P0443 EVAP Purge circiut malfunction or something like that. :roll:

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P0443 - Evaporative Emission Control System Purge Control Valve Circuit

OBD-II Trouble Code Technical DescriptionEvaporative Emission Control System Purge Control Valve Circuit

What does that mean?The Evaporative Emissions System (EVAP) allows fumes from the gas tank to enter the engine to be burned, rather than vented into the atmosphere as an emission. The purge valve solenoid is supplied switched battery voltage. The ECM controls the valve by operating the ground circuit, opening the purge valve at specific times allowing these gasses to enter the engine. The ECM monitors the ground circuit as well, watching for faults. When the purge solenoid isn't activated, the ECM should see a high voltage on the ground circuit. When the solenoid is activated, the ECM should see the ground voltage pulled low, close to zero. If the ECM doesn't see these expected voltages, or senses an open in the circuit, this code is set.

Potential Symptoms. P0443 trouble code symptoms could be just an malfunction indicator lamp (MIL) illumination. There may be no drivability problems at all. But, it's also possible to have a lean condition or a rough running engine if the purge valve is stuck open. Usually though, these symptoms are accompanied by other EVAP codes. Another symptom may be excessive pressure in the gas tank in the form of a "whooshing" sound when the cap is removed, indicating a purge valve that isn't working at all or stuck closed.

Causes. To cause a P0443, there has to be a problem with the purge control CIRCUIT, not necessarily the valve. Usually they are a unit housing the valve and the solenoid as an assembly. Or it could be comprised of a separate solenoid with vacuum lines to a purge valve. That said, it could be any of the following:

Bad purge solenoid (internal short or open)
Wiring harness chafing or rubbing another component causing short or open on control circuit
Connector worn, broken or shorted due to water intrusion
Driver circuit inside powertrain control module (PCM) is bad
Possible Solutions1. Using a scan tool, command the purge solenoid to activate. Listen or feel for a clicking coming from the purge solenoid. It should click once, or on some models it may click repeatedly.

2. If it doesn't click with scan tool activation, unplug the connector and examing the solenoid and connector for damage, water, etc. Then check for battery voltage on the feed wire with the key on. If you have battery voltage, then ground the control side manually using a jumper wire and see if the valve clicks. If it does, then you know the solenoid is working properly but there is a problem with the control circuit. If it doesn't click when you manually ground it, replace the purge solenoid.

3. To check for a problem on the control circuit (if the solenoid tests okay and you have voltage to the solenoid) plug the solenoid back in and remove the control circuit (ground) wire from the ECM connector (If you're unsure how to do this, do not attempt). With the ground wire removed from the ECM, turn the key on and then manually ground the Purge valve control wire. The solenoid should click. If it does, then you know there is no problem with the control wire to the solenoid and there is a problem with the ECM purge solenoid driver circuit in the ECM. You'll need a new ECM. However if it doesn't click, then there must be an open in the wiring between the ECM and and the solenoid. You must find it and repair it.

Had this same problem with my '96 5.0 AWD...replaced every solenoid and sensor in the evap system. Eventually replaced my carbon canisters above the spare tire and the problem went away. I think the canisters were clogged because they were much heavier than the replacement ones.

That one evaded me for quite a while also...turned to be mice chewed the wires off of the connector at the canister.

I am facing this nightmare right now and so far;

*New purge valve ( bought 2, neither one clicks, even when connected directly to 12v
*tested circuit and have 12 v to purge valve solenoid and pulsing ground once up to temp
* pulled canister and checked vent valve which does click and works fine
Still throwing P0443
Pulling my hair out, previous owner gave up after he replaced the PCM, no symptoms other than the Check engine light

Same problem in my moms MDX. Replaced every damn sensor, checked for leaks, spent tons of money just for a stupidass EVAP issue that doesn't even effect the 255k mile 2002 vehicle apart from failing inspection because the damn light is on. It's been on for 6 years and somehow I manage to squeeze through inspection by resetting the battery every time beforehand. So believe me I feel your pain.

I just bought a charcoal canister ($400 from Acura) for 60 bucks online and am going to replace that next.