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 the car's computer has found a problem with the part that helps stop gas fumes from escaping the fuel system. It's like a gate that won't close properly.
The P149B code indicates a low voltage condition in the circuit controlling the EVAP system shutoff valve.
The EVAP (Evaporative Emission Control) system is designed to prevent fuel vapors from escaping into the atmosphere. The shutoff valve is a component that helps control the flow of these vapors. A 'Control Circuit Low' condition suggests that the electrical circuit responsible for operating this valve is not receiving enough voltage, which could be due to a wiring issue, a faulty valve, or a problem with the control module.
• Check Engine Light is on
• Increased fuel odor
• Possible decrease in fuel efficiency
• Faulty EVAP shutoff valve
• Wiring issues in the EVAP control circuit
• Faulty control module
EVAP: Evaporative Emission Control
OBD-II: On-Board Diagnostics II
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors in the EVAP system for damage or corrosion.
• Test the EVAP shutoff valve for proper operation.
• Replace or repair damaged wiring or connectors.
• Replace the EVAP shutoff valve if faulty.
• Repair or replace the control module if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$100 - $300
Moderate
• Toyota Camry
• Honda Accord
• Ford Focus
• Regularly inspect and maintain the EVAP system.
• Ensure fuel cap is properly sealed.
• Avoid overfilling the fuel tank.
Sensor Issue
• Address the issue promptly to avoid emissions problems.
• Consult a professional mechanic if unsure about repairs.
Check with your vehicle manufacturer for warranty coverage on emissions-related components.
This code has been associated with issues in vehicles with aging EVAP systems, particularly in models over 5 years old.
Moderate – While not immediately critical, it should be addressed to maintain vehicle efficiency and emissions compliance.
Ignoring this code may lead to increased emissions, which can be illegal in some areas and harmful to the environment.
• Vehicle at operating temperature
• Fuel level between 15% and 85%
The EVAP shutoff valve is typically located near the fuel tank or along the EVAP canister line.
Q: Can I drive with a P149B code?
A: Yes, but it is advisable to fix the issue soon to avoid increased emissions and potential fuel efficiency loss.
Q: Will a P149B code cause my car to fail emissions testing?
A: Yes, a malfunctioning EVAP system can cause your vehicle to fail emissions tests.
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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.