What does it mean when the CPV valve is stuck in the open position?
4 Answers
Not CPV valve, it should be PVC valve, which means the car PVC valve is stuck in the open position. Here is some information about the car PVC valve: Composition: The car PVC valve is a device on the forced ventilation system of the car engine's crankcase, consisting of a valve body, valve, valve cover, and spring. Function: It directs the gas in the crankcase into the intake manifold through the PCV valve, and a small amount of air enters the intake manifold directly from the air filter through the PCV valve. This prevents icing at the throttle, incomplete combustion, and worsening emissions. It also prevents blow-by gases from entering the atmosphere and prevents engine oil from deteriorating.
The CPV valve stuck in the open position means that the evaporative emission valve in the car is jammed and remains open, unable to close, allowing fuel vapors from the gas tank to directly enter the engine for combustion. When this part fails, you might notice severe engine shaking at idle, unstable RPM, or even the sudden illumination of the check engine light. Over time, fuel consumption tends to increase, emissions exceed standards, and passing annual inspections becomes problematic. I experienced a similar issue with my old car before—the mechanic suggested that the valve might be clogged with dust or rusted due to aging, advising me to get it checked immediately to avoid damaging internal engine components. It's best not to delay repairs, as keeping it open continuously affects the engine's air-fuel mixture ratio, worsening driving performance and leading to higher repair costs. To determine if it's stuck open, you can start the car and listen for unusual engine noises or observe changes in dashboard warning lights.
The CPV valve being stuck in the open position means it is fixed in the open state and cannot move, failing to close as needed. This valve is designed to control the flow of fuel tank vapors, preventing them from leaking into the atmosphere. Once stuck open, vapors continuously enter the engine's intake manifold, disrupting the balance of air intake. The result is an imbalanced air-fuel ratio, potentially causing engine misfires, poor acceleration, and excessive emissions. I believe this issue is often caused by valve jamming or motor failure, such as debris blockage or insufficient lubrication. If left unaddressed, it can accelerate component wear and affect overall engine performance. Repairing it is not difficult—typically, after confirming with a diagnostic tool to read the fault code, cleaning or replacing the valve will suffice. Regular maintenance checks should include inspecting the evaporative system for proper sealing to detect potential issues early.
A CPV valve stuck in the open position means the valve remains constantly open and cannot close, directly affecting engine stability. Simply put, it should only open to release vapor at specific times, but now it stays open continuously, allowing vapor to constantly enter the combustion chamber. This leads to excessive air intake, causing unstable idle or sluggish acceleration, and you might notice abnormal vibrations at high speeds. The danger lies in the fact that delayed repairs can worsen emissions, pollute the environment, or even trigger the safety fault light. Common causes include carbon buildup inside the valve or mechanical jamming. I recommend stopping the vehicle for inspection as soon as the issue is detected to prevent further complications. Don’t underestimate this valve—its role is to maintain fuel system balance, and a stuck valve poses significant risks. If necessary, take it to a professional shop for diagnosis and repair.
