Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
The car has a tube that's supposed to help with air and oil fumes in the engine. On one side of the engine, this tube might be loose or broken.
This code indicates that the crankcase ventilation hose on Bank 2 of the engine is either disconnected or defective, affecting the engine's ability to manage air and oil vapors.
The crankcase ventilation system helps to reduce emissions by recirculating blow-by gases from the crankcase back into the intake manifold. If the hose is disconnected or defective, it can lead to incorrect air-fuel mixture and increased emissions.
• Check Engine Light is on
• Rough idle
• Decreased fuel efficiency
• Disconnected crankcase ventilation hose
• Cracked or damaged hose
• Faulty PCV valve
Crankcase: The housing for the crankshaft in an engine.
PCV Valve: Positive Crankcase Ventilation valve, a part of the engine's emission control system.
• Inspect the crankcase ventilation hose for disconnection or damage.
• Check for vacuum leaks in the system.
• Test the PCV valve for proper operation.
• Reconnect any disconnected hoses.
• Replace damaged or cracked hoses.
• Replace the PCV valve if faulty.
• Socket set
• Screwdriver
• Vacuum gauge
$50 - $150
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly inspect hoses for wear and tear.
• Replace PCV valve as part of routine maintenance.
• Ensure proper installation after maintenance work.
Engine Performance
• Have the vehicle inspected by a professional if unsure.
• Do not ignore the check engine light.
• Regular maintenance can prevent this issue.
Check with your vehicle manufacturer for warranty coverage on emissions-related components.
This code has been associated with vehicles that have high mileage or have not had regular maintenance.
Moderate – It should be addressed soon to prevent further engine issues.
Driving with a malfunctioning crankcase ventilation system can increase emissions and may not comply with local emissions regulations.
• Engine at operating temperature
• Engine idling
The crankcase ventilation hose is located on the engine, typically connected to the valve cover and intake manifold.
Q: Can I drive with a P121B code?
A: It's not recommended to drive for long periods with this code, as it can lead to increased emissions and engine performance issues.
Q: How often should I check the crankcase ventilation system?
A: It's a good idea to inspect the system during regular oil changes or every 10,000 miles.
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