P0443 Evaporative Emission Control System Purge Control Valve Circuit

Description and meaning of DTC p0443

This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles. Although generic, the specific repair steps may vary depending on make/model. The Evaporative Emissions System (EVAP) allows fumes from the gas tank to enterthe engine to be burned, rather than vented into the atmosphere as an emission. The purge valve solenoid is supplied switched battery voltage. The ECM controlsthe valve by operating the ground circuit, opening the purge valve at specifictimes allowing these gasses to enter the engine. The ECM monitors the groundcircuit 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 isactivated, 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. Note: This DTC is similar to P0444 and P0445.

p0443 diagnostic trouble code 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 possibleto have a lean condition or a rough running engine if the purge valve is stuckopen. Usually though, these symptoms are accompanied by other EVAP codes. Anothersymptom 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 atall or stuck closed.

DTC p0443 - possible 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 thesolenoid as an assembly. Or it could be comprised of a separate solenoid withvacuum 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 openon control circuit Connector worn, broken or shorted due to water intrusion Driver circuit inside powertrain control module (PCM) is bad

How to fix OBD-II diagnostic trouble code p0443

1. Using a scan tool, command the purge solenoid to activate. Listen or feelfor a clicking coming from the purge solenoid. It should click once, or on somemodels it may click repeatedly. 2. If it doesn't click with scan tool activation, unplug the connector andexaming the solenoid and connector for damage, water, etc. Then check for batteryvoltage on the feed wire with the key on. If you have battery voltage, thenground 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 problemwith the control circuit. If it doesn't click when you manually ground it, replacethe purge solenoid. 3. To check for a problem on the control circuit (if the solenoid tests okayand you have voltage to the solenoid) plug the solenoid back in and remove thecontrol circuit (ground) wire from the ECM connector (If you're unsure how todo this, do not attempt). With the ground wire removed from the ECM, turn thekey on and then manually ground the Purge valve control wire. The solenoid shouldclick. If it does, then you know there is no problem with the control wire tothe solenoid and there is a problem with the ECM purge solenoid driver circuitin the ECM. You'll need a new ECM. However if it doesn't click, then there mustbe an open in the wiring between the ECM and and the solenoid. You must findit and repair it. Other EVAP DTCs: P0440 - P0441 - P0442 - P0444 - P0445 - P0446 - P0447 - P0448 - P0449 - P0452 - P0453 - P0455 - P0456

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