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 there is a problem with the part of the car that helps get rid of gases from the engine. It's like if a pipe in your house was blocked and couldn't let air out.
The P120B code indicates a low voltage signal from the crankcase ventilation diagnostic valve circuit.
The crankcase ventilation system helps manage the gases that escape from the engine's crankcase. The diagnostic valve is a part of this system, and it monitors the flow of these gases. A 'circuit low' condition suggests that the electrical signal from the valve is lower than expected, which could mean a wiring issue or a faulty valve.
• Check Engine Light is on
• Poor engine performance
• Increased emissions
• Faulty crankcase ventilation diagnostic valve
• Wiring issues such as short circuits or open circuits
• Faulty engine control module (ECM)
Crankcase: The part of the engine that houses the crankshaft.
Diagnostic Valve: A component that monitors and controls the flow of gases in the crankcase ventilation system.
• Use an OBD-II scanner to confirm the P120B code.
• Inspect the wiring and connectors for the crankcase ventilation diagnostic valve.
• Test the crankcase ventilation diagnostic valve for proper operation.
• Replace the faulty crankcase ventilation diagnostic valve.
• Repair or replace damaged wiring or connectors.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Wrench set
$150 - $400
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly inspect and maintain the crankcase ventilation system.
• Ensure all electrical connections are secure and free of corrosion.
• Follow the manufacturer's maintenance schedule.
Sensor Issue
• Do not ignore the Check Engine Light; get it checked as soon as possible.
• Regular maintenance can prevent such issues.
• Consult a professional mechanic if unsure about the repair.
Check with the vehicle manufacturer for warranty coverage on emissions-related components.
This code has been associated with issues in vehicles with advanced emissions systems, often due to aging components or wiring problems.
Moderate – It should be addressed soon to prevent potential engine performance issues.
Ignoring emissions-related issues can lead to failing emissions tests and potential fines.
• Engine at operating temperature
• Vehicle at idle
The crankcase ventilation diagnostic valve is typically located on or near the engine block.
Q: Can I drive with a P120B code?
A: It's possible to drive short distances, but it's best to address the issue soon to avoid further damage.
Q: Will the P120B code cause my car to fail an emissions test?
A: Yes, a malfunctioning crankcase ventilation system can increase emissions and lead to a failed test.
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