JimiDiddle

Have an issue that is stumping me...99 Jeep XJ. Constantly getting CEL and a P0443 code upon startup after cool down. I have replaced the purge valve/solenoid and verified that it kicks on and is clicking after temp reaches 150 degrees. I checked keyed on voltage at 12 and the PCM ground switch side at 5 volts. I understand this code to be related to improper voltage values at startup when the PCM looks at the purge valve solenoid loop. Interesting enough the code itself doesn't show up as an trouble code but I can see it in freeze frame data? Anyone run into this issue. Absolutely no drivability issues at all. Bugs me because I can't pass emissions with this CEL on.

JimiDiddle

Been reading a lot about possible PCM issues with 99 XJ regarding this code. Hoping to hear from some others who've experienced this before I plop down the $$ for a replacement one...

Sandyman

Found this that might help you.

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 Solutions 1. 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.

JimiDiddle

Thanks for this info. Weird part is the purge solenoid is working. I can feel it clicking away once Jeep gets to temp. I replaced to valve anyways just to be certain but still no luck. I know the ECM is commanding the ground loop because of the clicking. I have proper voltage but still no luck on the start up after sitting for a while. It always throw the code after being off for 10 min or more. I am stumped and it is getting irritating. I just read something about electrical "noise" from the ignition switch causing the ECM issue throwing the P0443 code. ?????