P0443: EVAP System Purge Control Valve “A” Circuit Malfunction

What is P0443?

P0443 is a diagnostic trouble code (DTC) defined as “Evaporative Emission Control System Purge Control Valve “A” Circuit Malfunction.”

It’s a generic engine code triggered when the engine control module (ECM) detects a malfunction with the purge control valve or its control circuit.

Your vehicle’s EVAP system works like a closed container for gasoline vapors from your fuel system, preventing them from escaping into the atmosphere. Fuel vapor is stored in the charcoal canister, and the purge valve (opened and closed by a solenoid) controls when the vapor is released. 

The engine control module controls the purge valve by switching the electrical connection to ground on or off. When the valve opens, fuel vapors stored in the charcoal canister flow into the intake manifold, where they’re burned during combustion.

To make sure the system works correctly, the ECM also monitors the ground wire. It should show: 

• A high voltage when the valve is off
• A voltage drop close to zero when the valve is on.

If the ECM doesn’t see these regular voltage changes or detects a loose connection, it sets code P0443 and turns on the check engine light.

NOTE: P0443 is a generic code defined by the Society of Automotive Engineers (SAE), but the specifics differ across automakers. For instance, on the 2011 F-150 XL 3.7L V6 (a Ford model), it means the ECM sees the purge valve circuit signal outside its normal range.

What Symptoms Accompany a P0443 Code?

Some common signs that indicate a P0443 fault code include:

1. An illuminated check engine light: This is the vehicle’s way of alerting you that the ECM has detected an issue with the EVAP system.

2. Difficulty starting or engine stalling: If the purge valve isn’t working correctly, it can upset the air-fuel mixture, making the engine start poorly or stall.

3. Strong fuel odor: A broken purge valve can let fuel vapors escape from the EVAP system and cause a gasoline smell around the gas tank or engine bay.

4. Reduced fuel efficiency: A faulty purge valve can affect how the fuel vapor is recycled into the engine. Instead of being burned, some vapors may stay trapped, leading to reduced fuel economy and lower miles per gallon.

5. Increased emissions: A fault in the EVAP system can cause higher emission readings during an emissions test.

What Triggers the P0443 Code?

A P0443 diagnostic trouble code can show up due to the following reasons:

• A malfunctioning purge valve 
• Issues in the purge valve circuit, such as loose electrical connections or damaged wiring, that disrupt the signal
• A faulty ECM (in rare cases)

Is it Safe to Drive with a Code P0443?

Car experts generally advise against driving with a P0443 code. 

A faulty purge valve can increase vehicle emissions and waste fuel. This problem may also lead to performance issues such as rough idling or even engine stalling.

Ignoring this issue can put extra strain on the EVAP system, leading to expensive repairs down the line. Additionally, your vehicle will likely fail its next emissions or smog test.

How to Diagnose and Fix the P0443 Error Code

You shouldn’t attempt to fix a P0443 error code yourself unless you have automotive experience. The repair involves handling electrical parts and mistakes can create bigger issues or risks. 

That’s why it’s best to let a qualified technician handle the diagnosis and necessary repairs.

Here’s how they’ll go about troubleshooting the problem:

1. Connect an OBD-II scanner to verify that the stored code is P0443. They’ll check if any other related EVAP system codes (such as P0446 and P0449) are present, as they may point to other potential issues.

2. Check for any damaged wire that could lead to an open circuit in the purge solenoid wiring system. They’ll also check the electrical connector to make sure it’s free from corrosion or bent terminals. They’ll repair or replace the damaged wiring or connector if needed.

3. Verify that the connector is receiving proper voltage and ground, using a multimeter. If the circuit is functioning but the purge solenoid is faulty, the technician will replace the defective purge valve.

4. Using a test light, check the vehicle’s fuses. If any are blown, they will replace the damaged fuse.

5. Ensure that the gas cap seals properly, as it is one of the most common causes behind an active check engine light. They’ll inspect the gas cap gasket for tears or cracks. If the fuel cap is damaged, they will replace it to ensure a proper seal.

6. Use a gauge or scan tool to measure the pressure readings and determine if the gas tank pressure sensor is working correctly. If it is faulty the mechanic will replace the sensor.

7. Check all the hoses and lines in the EVAP system and look for signs of wear.

8. Run a smoke test to check the EVAP system for leaks and repair these.

9. Confirm that the ECM is sending the correct commands to the purge valve. They’ll reprogram or replace the ECM if it is faulty (only in rare cases).

10. Clear the code from the system once the necessary repairs are complete. The mechanic will also perform a test drive to ensure the error code is resolved.

How Much Does it Cost to Fix the Error Code P0443?

Repairing a P0443 code can cost anywhere from $160 to $1,650, depending on which EVAP system components need replacement.

Here are the estimated expenses (including parts and labor):

• Diagnosis fee: $50 to $170
• EVAP hose or line repair: $50 to $100
• Gas cap replacement: $110 to $130
• Purge valve replacement: $180 to $320
• Fuel tank pressure sensor replacement: $265 to $380
• ECM replacement: $800 to $1,500

How to Avoid Triggering the P0443 Code

Here are some maintenance tips for vehicle owners to prevent a P0443 fault code:

• Avoid aggressive driving to prevent physical damage to the EVAP system components.

• Timely repairs and maintenance of the purge control valve, charcoal canister, hoses, and connections can keep your EVAP system healthy. Consult the owner’s manual for exact service intervals.

• When replacing components, use high-quality parts from trusted brands.

• Avoid overfilling the fuel tank to prevent gasoline from entering the EVAP system and damaging components like the charcoal canister.

• Tighten the fuel cap securely after every refueling to prevent vacuum leaks in the EVAP system.

• Keep the area around the fuel tank clean to prevent debris and moisture build-up, which can lead to corrosion on the valve and electrical connectors.