The evaporative control (EVAP) system helps prevent fuel vapors from being released into the atmosphere. Depending on the issue experienced by the EVAP system, your car’s primary computer, which is often referred to as the powertrain control module (PCM), can log different diagnostic trouble codes—one such code is a P0443.
What Does the P0443 Code Mean?
Diagnostic trouble code (DTC) P0443 stands for Evaporative Emission System Purge Control Valve “A” Circuit. The code indicates that the PCM perceives a problem with the EVAP system purge valve or its control circuit.
Note: Although code P0443 is a generic code specified by the Society of Automotive Engineers (SAE), the code’s definition may be different depending on the vehicle manufacturer.
Examples of other diagnostic trouble codes pertaining to the EVAP system include P0440-P0449, P0452-P0453, and P0455-P0456.
Like the P0443 code, the P0444 code (EVAP Purge Control Valve Circuit Open) and P0445 code (EVAP Purge Control Valve Circuit Shorted) also relate to the purge control valve.
The EVAP System and Purge Valve
As mentioned, the EVAP emissions system prevents fuel vapors from being released into the atmosphere. The heart of the system is the charcoal canister—a device that traps the fuel vapors when the engine is off.
Once the engine is running and conditions are correct, the PCM commands the purge valve open to allow the vapors to enter the engine. The vapors are then burned during the normal combustion process.
The PCM monitors the integrity of the purge valve and the valve’s control circuit. When the module detects an electrical fault with either the valve or the circuit, it will set code P0443.
What are the Symptoms of the P0443 Code?
In many cases, the only symptom that would accompany the trouble code P0443 is an illuminated check engine light. However, you may observe other telltale signs, particularly if there are other codes stored in addition to P0443.
If that is the case with your vehicle, the causes and symptoms may differ from those listed here.
Here are the two most common symptoms:
- An illuminated check engine light
- Engine performance problems, such as rough running and hesitation (if the purge valve is stuck open)
What are the Causes of the P0443 Code?
The following problems can prompt the PCM to log a P0443 code:
- A bad purge valve
- Problems with the purge valve circuit, such as loose connections and damaged wires
- A problem with the PCM (rare)
How to Diagnose the P0443 Code
Typically, either a circuit fault or problem with the purge valve will trigger code P0443. Because diagnosis can be tricky, if you’re uncertain of your automotive aptitude, you may want to leave the task to a professional.
However, if you’d like to perform the diagnosis yourself, check out the videos below to get an idea of what the troubleshooting process involves:
How to Fix the P0443 Code
By now, you probably get the idea: There is no “magic bullet” fix for code P0443. What complicates things further is the fact the diagnosis and repair of the problem can vary by vehicle.
That’s why only vehicle owners with sufficient technical knowledge should attempt DIY fixes on a vehicle with a P0443 code. Otherwise, bring the vehicle to the nearest auto repair shop and get a trained professional to repair the problem.
If you do decide to tackle fixing the code yourself, keep in mind that different types of vehicles may require their own distinct solutions. For that reason, you should always consult the appropriate repair information for your application.
Repair manuals, such as those from Chilton, are useful, but an ALLDATA subscription is even better. ALLDATA has single-vehicle subscriptions for DIYers that provide detailed factory repair information.