Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's a problem with a part of the car that helps control pollution. It's like a door that lets air in and out of a balloon, but the door is stuck open or not working right.
The P0499 code indicates that the powertrain control module (PCM) has detected a high voltage condition in the circuit that controls the EVAP system vent valve.
The EVAP (Evaporative Emission Control) system is designed to prevent fuel vapors from escaping into the atmosphere. The vent valve is a component of this system that allows fresh air to enter the charcoal canister. When the PCM detects a high voltage in the vent valve control circuit, it triggers the P0499 code.
• Check Engine Light is on
• Increased emissions
• Possible fuel odor
• Faulty EVAP vent valve
• Wiring issues, such as damaged wires or poor connections
• Faulty PCM (Powertrain Control Module)
EVAP: Evaporative Emission Control System
PCM: Powertrain Control Module
• Use an OBD-II scanner to confirm the code.
• Inspect the EVAP vent valve and its wiring for damage.
• Test the voltage and ground signals at the vent valve connector.
• Replace the EVAP vent valve if faulty.
• Repair or replace damaged wiring or connectors.
• Reprogram or replace the PCM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$100 - $400
Moderate
• Chevrolet Silverado
• Ford F-150
• Toyota Camry
• Regularly inspect EVAP system components.
• Ensure proper connections and wiring integrity.
• Perform routine vehicle maintenance.
Sensor Issue
• Address the issue promptly to avoid increased emissions.
• Consult a professional mechanic if unsure about repairs.
Check with the vehicle manufacturer for specific warranty coverage on emissions-related components.
The P0499 code has been observed in various models, often related to wiring or vent valve issues.
Moderate – While not immediately dangerous, it should be addressed to prevent emissions issues.
Ignoring emissions-related issues can lead to failed emissions tests and potential fines.
• Vehicle at operating temperature
• EVAP system readiness monitors set
The EVAP vent valve is typically located near the fuel tank or charcoal canister.
Q: Can I drive with a P0499 code?
A: Yes, but it's best to fix it soon to avoid emissions problems.
Q: What causes high voltage in the EVAP vent valve circuit?
A: It could be due to a faulty valve, wiring issues, or a problem with the PCM.
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Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
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Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
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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.