How to Test Purge Valve with a Multimeter

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Are you searching for a practical way to test your purge valve using a digital multimeter? Look no further because you are in the perfect place! 

What is a Purge Valve? 

A purge valve, also known as the purge valve, is a key part of your Evaporative Emission Control (EVAP) system. That system controls the fuel vapors generated in your fuel tank from evading into the atmosphere by confining them in a charcoal canister. 

The EVAP system slowly lets such vapors be freed into the engine that burns like regular fuel when your engine starts to run at a regular speed. The flow of such vapors is regulated by the purge valve, regulating how much and when such vapors enter the engine. 

What are the Common Signs of a Failing Purge Valve? 

Keep in mind that the purge valve electrically runs and is called a solenoid. The most typical purge valve concerns occur every time the purge valve is stuck closed or open or doesn’t open promptly. The 

  • Problems with the engine

Is the purge valve stuck open, but it makes vacuum leaks that could impact your engine substantially? Take note that the air will be permitted to enter the engine in an amount not predicted by the vehicle’s computer.

That will change the vehicle’s air to fuel ratio and cause rough idling (the car feels bouncy and rough when the engine is running) and has problems starting. If encountered in tandem, there’s a high chance of a bad canister valve or some other component of the EVAP system.

  • Lower gas mileage

Is your purge valve not opening correctly? It might substantially impact the gas mileage. That is because the vapor your vehicle uses in combustion will find the EVAP canister and later on be vented to the surrounding. That indicates you’ll lose a part of the fuel regularly utilized in burning. 

  • Check engine light is one

Another symptom of a bad purge valve is the check engine light. Bear in mind that your vehicle’s computer regulates the purge valve. That enables it to track its overall performance. If your vehicle’s computer notices lower or higher than expected purging from the valve, it will lighten the check engine line.

Typical problem codes involve EVAP codes, such as P0446 and P0441, among other EVAP codes. Ensure you bring your vehicle to a qualified mechanic who can help assess the issue, especially if you check your engine light turns on.  

How Do You Test a Purge Valve? 

A purge valve is essential in any car that uses a combustion engine. It takes vapors from the fuel tank through an input hose. If the valve is running properly, it utilizes a 12V supply from the vehicle’s control computer.

That control computer commands the two main operating modes of the purge valve: CLOSE and OPEN. Then, the fuel vapors go through the purge valve and move into the outlet hose. From there, they go through the intake manifold and into the car’s engine to be combusted as fuel. 

A stuck close purge valve means an alert light will be triggered, informing you there’s a problem. Is your car engine beginning to exhibit rough idling? Maybe you have to have a difficult time starting the vehicle, particularly during the winter season. It would help if you tested the purge valve with a digital multimeter. 

Meanwhile, a stuck open purge valve can result in rough idling of the engine as well as engine misfiring. That can also result in problems starting the engine, particularly during winter. That is because a stuck open purge valve makes an air vacuum leak within the intake hose.

That makes a sucking of extra added air from the fuel tank that is more than is necessary. It then disrupts the overall operation of the engine. The worst thing about it is that you could go for weeks without even noticing there’s a problem. 

The reason behind it often doesn’t register a code until the purge valve is totally damaged, as there’s no blockage of air vapors from the fuel tank to the engine. 

It is about time that you understand the proper way to test a purge valve with a multimeter. To start the test, here’s what you need: 

  • Rubber hose with clamps
  • Battery power supply
  • Multimeter
  • Purge valve
  • Air pump 

Testing for continuity test

To do the continuity test, here’s what you need to do:

  1. Disconnect or remove the purge valve from the car’s engine. That could be performed by unbolting the clamps for both the outlet and inlet hoses from the fuel tank and engine, respectively. 
  1. Make sure your car has been idle for approximately thirty minutes. If you aren’t comfortable doing that, feel free to call a qualified mechanic, or you can bring your vehicle to a service station. 
  1. Set your digital multimeter to continuity mode after you have the purge valve. Continuity mode is where your meter will create an audible sound if you were to touch the two probes. 
  1. Connect the probes to the purge valve’s power terminals. Do you hear an audible sound? Then that means your purge valve is working perfectly fine. Keep in mind that many purge valves are solenoid. That means there’s a metallic or copper coil inside their casing from the negative and positive power terminals.
  1. If you don’t hear any audible noise, that means your purge valve is damaged and should be changed right away. 

Testing the ohm meter readings

  1. Now, move the dial’s multimeter to be on the ohm-meter setting. 
  1. Take the two lead probes and put them on the purge valve’s power terminals. 
  1. Your digital multimeter should provide you a reading. Commonly, a reading within the range of fourteen to thirty ohms indicates the purge valve is fine. If you have readings below or above that range, there could be an issue with the purge valve and might need to be changed right away. 

Final Thoughts

A purge valve is a relatively cheap repair. If you find it has a problem, consult a reliable technician right away!

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