Question about 1997 Nissan Maxima
P0443 - Evaporation Emission Control System Purge Control Valve Circuit
Hi. This code is referring to a malfunctioning Valve circuit, or defective purge solenoid.
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(emission control device). The purge valve solenoid is supplied voltage by the battery, and regulated by a switch. The ECM controls the valve by operating the ground circuit, opening the purge valve at specific times, thus, 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 registered as a low current, close to zero. If the ECM doesn't see these expected voltages, or senses an open circuit, this code is issued.
Symptoms could be just a malfunction indicator lamp (MIL) illumination. There may be no driving issues 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, the symptoms are accompanied by other EVAP codes. Another symptom may be excessive pressure in the gas tank in the form of a over pressured sound when the cap is removed, indicating a purge valve that isn't working at all or stuck closed.
1. Bad Solenoid(mechanical failure, or shorted circuit)
2. Shorted control circuit, or bad harness connection
3. Water Damaged connection
4. Bad ECM/PCM
1. It is possible to use a diagnostics scan CPU to command the purge valve to operate, manually. 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, unplug the connector, and examine the solenoid and connector for damage(water). 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. If it dose click, this will confirm that the solenoid is functional, and the ECM/PCM will be the culprit(Damaged control circuit).
Posted on May 01, 2011
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Posted on Jan 02, 2017
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