Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This means there's a problem with a part of the car that helps control the air and gases inside the engine. It's like a vent that isn't working right.
The P120A code indicates that the voltage in the crankcase ventilation diagnostic valve circuit is higher than expected.
The crankcase ventilation system helps manage the gases and pressure inside the engine's crankcase. The diagnostic valve in this system is monitored by the engine control module (ECM). If the ECM detects a voltage level that is too high, it triggers the P120A code.
• Check Engine Light is on
• Poor engine performance
• Unusual engine noises
• Faulty crankcase ventilation diagnostic valve
• Wiring issues such as shorts or open circuits
• Faulty ECM
ECM: Engine Control Module
OBD-II: On-Board Diagnostics, Second Generation
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage or corrosion.
• 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 - $500
Moderate
• Volkswagen Jetta
• Audi A4
• BMW 3 Series
• Regular maintenance and inspections
• Ensure proper oil levels
• Use quality replacement parts
Sensor Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional mechanic.
Check with the vehicle manufacturer for specific warranty coverage related to emissions components.
This code has been associated with vehicles that have complex crankcase ventilation systems, particularly in European models.
Moderate – While the car may still be drivable, it should be inspected soon to prevent further damage.
Driving with a malfunctioning crankcase ventilation system can lead to increased emissions and potential engine damage.
• Engine at operating temperature
• Vehicle in a safe, stationary position
The crankcase ventilation diagnostic valve is typically located on or near the engine block.
Q: Can I drive with the P120A code?
A: It's not recommended to drive for long periods with this code active, as it may lead to engine damage.
Q: How can I clear the P120A code?
A: After repairs, you can clear the code using an OBD-II scanner. If the issue is resolved, the code should not return.
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