Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that a part in your car that helps control gas fumes is not opening like it should. Imagine a door that is stuck and won't open, so the air can't get through.
The EVAP system is responsible for capturing fuel vapors from the gas tank and sending them to the engine to be burned. The purge control valve is a key part of this system, and if it's stuck closed, vapors can't be purged properly.
The P04AF code indicates that the Engine Control Module (ECM) has detected that the EVAP system purge control valve 'B' is not opening as commanded. This valve is supposed to open to allow fuel vapors to be drawn into the engine for combustion. When it remains closed, it can cause an imbalance in the air-fuel mixture, affecting engine performance and emissions.
• Check Engine Light is on
• Increased emissions
• Poor fuel economy
• Faulty purge control valve
• Electrical issues such as a short or open circuit
• Blocked or kinked vapor lines
EVAP: Evaporative Emission Control System
ECM: Engine Control Module
• Use an OBD-II scanner to confirm the code.
• Inspect the purge valve and its connections for damage or blockage.
• Test the electrical circuit for continuity.
• Replace the faulty purge control valve.
• Repair or replace damaged wiring or connectors.
• Clear any blockages in the vapor lines.
• OBD-II scanner
• Multimeter
• Wrench set
$100 - $250
Moderate
• Toyota Camry
• Ford F-150
• Honda Civic
• Regularly inspect EVAP components for wear.
• Ensure proper fuel cap sealing.
• Perform routine maintenance checks.
Emissions Control
• Do not ignore the Check Engine Light.
• Get the vehicle inspected by a professional.
• Avoid overfilling the gas tank.
Check with your vehicle manufacturer for warranty coverage on emissions components.
This code has been more common in vehicles with high mileage or those frequently driven in stop-and-go traffic.
Moderate – While not immediately critical, it should be addressed to avoid increased emissions and potential damage to the EVAP system.
Driving with an emissions-related issue may not pass state inspections and could lead to fines.
• Vehicle at operating temperature
• Engine running at idle
The purge control valve is typically located near the engine or along the fuel vapor lines.
Q: Can I drive with a P04AF code?
A: While the car may still run, it's not advisable to drive for long periods as it can increase emissions and affect fuel economy.
Q: How do I know if the purge valve is stuck closed?
A: A diagnostic test with an OBD-II scanner can confirm if the valve is stuck, often accompanied by a Check Engine Light.
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Fitment Required · Vehicle-fitment part
Relevant when EVAP diagnosis points toward purge-flow or purge-control faults.
EVAP diagnosis often includes purge-flow and valve-control faults.
Confirm the failed valve and exact fitment before buying parts.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.