Symptoms of a Bad Purge Valve

by Josh BoydUpdated June 07, 2023
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Today's cars have a lot of emissions-related equipment, which is all meant to cut down on an engine's smog production and air pollution. Though these parts can take a lot of wear and tear, they do break down on occasion. Your car's purge valve is one such component, and it's vital that this part work properly.

Though important, many drivers struggle to recognize a lot of faulty purge valve symptoms. But with the following tutorial, you'll be able to identify and know how to address those issues.

How Do I Know if My Purge Valve Goes Bad?

The following symptoms serve as a possible indication that your vehicle's purge valve has failed or is in the process of failing. Learning to recognize these symptoms can prove valuable when attempting to expedite any necessary repairs:

  • Check engine light
  • Starting difficulties
  • Rough or erratic idle
  • Compromised engine performance
  • Reduced fuel economy

Bad Purge Valve Symptoms

Now that you know what to look for when trying to figure out if your vehicle's purge valve has gone bad, let's dig into the details of these symptoms a little further. This will provide you with a greater understanding of why these symptoms are arising in the first place.

Check engine light

Evaporative emissions-related issues are among the most common causes of active check engine lights. When a vehicle's ECM/PCM identifies an issue with this system, a diagnostic trouble code is logged, and a check engine light is illuminated. One of the most common of all evaporative emission control systems (EVAP) trouble codes is "Evaporative Emissions High Purge Flow" (P0496).

Starting difficulties

Issues pertaining to a faulty EVAP purge solenoid can actually create a significant vacuum leak. Simply put, this leakage allows large quantities of unmetered air into an engine's intake, thereby skewing the engine's air/fuel ratio. This, in turn, often causes starting-related difficulties.

Rough or erratic idle

For many of the same reasons mentioned above, a "stuck-open" purge valve can cause a vehicle to idle unpredictably. The introduction of unmetered air into a vehicle's engine undermines the powertrain and engine control units' abilities to effectively control operating air/fuel ratios.

Compromised engine performance

In severe cases, the vacuum leak created by a faulty purge valve can actually become significant enough to compromise engine performance as a whole. When this occurs, one might feel as if their vehicle lacks any meaningful power, even when depressing the throttle pedal to the floor.

Reduced fuel economy

In many cases, a faulty purge valve will vent gas vapors before they can be redirected for combustion. As a result, fuel usage becomes less efficient than it otherwise would be. In turn, a vehicle's fuel economy is sure to suffer.

Purge Valve Replacement Cost

Luckily, the cost of purge valve replacement tends to be much less than that of many other automotive repairs. While the cost of such repairs varies from one vehicle to the next, there is an average price range in which the bulk of purge valve replacements falls.

On average, one can expect to pay between $75 and $250 to have their vehicle's purge valve replaced. Again, the exact cost incurred depends on the model of vehicle being repaired, the price of the parts involved and the hourly labor rate of the individual shop that is performing these repairs.

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