What is a Canister Purge Valve In A Vehicle?

2023-02-28 By ren

Introduction To Canister Purge Valve (CPV)

The history of the Canister Purge Valve is useful to understand why CPV valves were invented. By 1967 the State of California established the California Air Resources Board, and the federal United States founded the Environmental Protection Agency in 1970 to observe the air pollution.

Since then it was confirmed that the fuel emission of an engine shouldn’t be entered directly to the atmosphere. The reason was unburnt fuel vapors were dangerously emitting CO2, CO to harm Ozone layer. Thus, the unburnt fuel should be regulated inside engine combustion before entering the environment.

Finding and replacing a canister purge valve with Valve GMK high quality valve

For this purpose an engine seal emission system was considered including PCV valve and CPV valve. After 1971 all cars had an emission fuel control system, so CPV.

In this blog post, we are going to discuss what is  a canister purge valve? How does it work? What are its common problems and solutions? 

What is a Canister Purge Valve (CPV)?

The Canister Purge Valve (CPV) is an important component of an evaporative emission control system (EVAP) of a vehicle. During combustion in an engine the fuel vapors that are harmful for the environment are also released. Therefore, this emission control component plays a vital role by preventing harmful fuel vapors going into the environment. Moreover managing the exact flow of flue vapors in the engine manifold.

How does Canister Purge Valve work?

Ultimately the CPV valve’s purpose is to make sure fuel emissions do not vent directly to the atmosphere by manifold. So emission is stored in the carbon canister and intake into the engine to burn off the gasoline vapors before venting to the atmosphere. It not only makes the environment better but also increases the fuel efficiency of a car.

When the engine is running, the emission control system opens the canister purge valve allowing fuel vapors to pass through the intake manifold to fully burn with air/fuel mixture of the engine.

Common Problems with CPV

Like any other vehicle component, the Canister Purge Valve has a life span and it can become faulty over-time. Usually the life of components of an engine is denoted by mileage. On average, a well maintained car can experience a canister purge valve or PCV valve faulty after 100000 miles. So it is crucial to replace it with a high quality valve

Here are the most common issues with a faulty CPV:

Check Engine Light (CEL): A faulty Canister Purge Valve can be caught by the vehicle’s diagnostic sensor system. Using a scanner or code set, the problem can be diagnosed and severity can be noticed.

Rough Idle: A faulty canister purge valve will make rough idling or stalling of the engine.

Visible smoke: Because of the untreated emission the smoke will be visible from exhaust.

Low Fuel Economy: It can also cause poor fuel economy if it is stuck open or closed. The reason would be incorrect fuel vapor flow to the engine.

Problems with cold starting: A vehicle with faulty CPV creates a problem with cold starting.

Presence of oil at exhaust. If you notice the presence of oil at exhaust it could be due to CPV stuck open. 

Fixing the Canister Purge Valve Problems

Fixing a CPV valve will require an auto workshop visit if you don’t have appropriate skills and tools. 

However, we will try our best explaining how you can replace a faulty canister purge valve with a new one. If the problem has been diagnosed you need to:

  1. Open the hood, remove the battery’s connection from one terminal.
  2. Figure out where your CPV valve is located, it should be visible near the intake manifold, with a pipe coming from a canister hub to the intake manifold.
  3. Unscrew the faulty CPV and replace it with a new one, also make sure you reattach the pipes properly. There should be no gap.
  4. Reconnect the terminal of the battery you removed and switch on the engine.
  5. The check engine light should be vanished.


The canister purge valve is an important component in an engine that prevents fuel vapors from entering the environment without treatment. Though it is a small piece it has great value preventing hazardous smoke from venturing into the environment. Usually after 100000 miles it gets weakened or even stuck in an open or close direction.

A high quality canister purge valve should be installed otherwise it will stick once again. To purchase a high quality CPV valve you can browse the GMK-VALVE catalog containing high quality valves.



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