Fault code P0443 – a step-by-step guide to diagnosing and fixing it

DTC P0443 indicates that the engine control module (ECM) has detected a problem with the evaporative emission control (EVAP) system purge valve or its control circuit. The ECM controls the valve, regulating the flow of gases by opening and closing it at specific times. If it detects an open in the devices circuit or recognises that the voltage isnt as it should be when the control solenoid is activated or deactivated, it will set the code.

• An internal short or open in the solenoid circuit or a corroded connector, causing a poor connection to the valve. This could occur due to internal or external damage. A loose or cracked connector will expose the electrical contacts to moisture, fluids, and dirt, leading to corrosion. If the wiring harness is coming into contact with other components, this could also be the cause.
• A damaged signal or power cable. This can be caused by mechanical wear or thermal damage, for example.
• A jammed valve. The components can get stuck due to a build-up of contaminants, such as an accumulation of dust from the charcoal canister.
• A problem with the ECM. This can trigger a false error, although this is quite rare.

• Activation of the check engine light
• Jerking while driving
• A rough idle
• Reduced fuel efficiency
• A whooshing or hissing sound when the car fuel capis removed due to high pressure
• Lean engine conditions
• A loss of power or decreased acceleration

• Connect an OBD2 scanner to the vehicle via the data link connector port and scan for other DTCs. This will help you to identify the root cause of the malfunction. Other EVAP DTCs may appear, including P0440, P0444, P0447, P0458, P0459. P0440 is a general code, covering most EVAP system failures.
• It may be possible to activate the purge valve via the ECM using the scan tool. It should make a clicking sound when activated. If you dont hear a click, disconnect the connector and check the device and connector cable for damage. Then switch on the ignition without starting the engine. Measure the voltage in the feed wire with a multimeter and, if the wire is working, use a jumper wire to carefully ground the control yourself. If the valve starts to click, it means that the device works, and if not, replace the purge solenoid.
• Inspect the wiring to the valve thoroughly. Reconnect any loose wires and replace damaged ones. You may need to remove rust and contaminants from the contacts to restore their conductivity. Use special hydrophobic products to prevent further corrosion.
• Contaminated valve components should also be cleaned to ensure that the mechanism operates smoothly. This is done using a specialised cleaning agent or compressed air.
• Once you have finished repairing the unit, you can erase the codes from the computers memory archive using the diagnostic scan tool.