The third-generation Toyota Prius is a reliable and efficient vehicle, but you'll still need to pay attention to a few maintenance issues to keep yours on the road. Like any car, there are common failure points that will occasionally require attention and repair. One common problem experienced by many Prius owners relates to the EGR valve.

Don't worry if you aren't familiar with this particular component. Although the EGR system isn't unique to the Prius, it is a somewhat esoteric emission and efficiency-related part. Learning a bit about how your car's EGR system works, and the symptoms of a failing EGR valve, can help you repair problems early on to keep your vehicle running as efficiently as possible.

What is Exhaust Gas Recirculation (EGR)?

Manufacturers have prioritized improved efficiency and reduced emissions for years. The exhaust gas recirculation system is one standard method manufacturers use to make their engines run cleaner while also putting elements of the exhaust stream to productive use. As you might have guessed from the name, the EGR takes a portion of your exhaust gases and returns them to the combustion chamber.

In essence, the EGR system opens a path between the exhaust manifold (which allows combustion gases to escape) and the intake manifold (which brings fresh air into the engine). Under normal circumstances, negative pressure in the combustion chamber draws air into the engine through the intake manifold. The EGR system allows the engine to also pull some amount of exhaust gases along with the air.

However, your engine relies on a careful balance between oxygen and fuel to operate at peak efficiency. The presence of exhaust gases changes the makeup of the intake air, offsetting this balance to improve emissions. While this typically doesn't impact performance, too much exhaust gas can ruin your air-to-fuel ratio. The EGR valve therefore monitors and regulates the flow of exhaust gases into the engine.

Is Your EGR Valve Failing?

Your exhaust stream contains small amounts of carbon, which can clog the EGR valve's physical mechanisms over time. Clogs or wear can result in a valve stuck open or closed (or anywhere in between), ultimately impacting the performance of your Prius. A valve that's stuck open might sap your engine of its power, while a closed valve can impact emissions and fuel economy.

In many cases, the first sign of trouble will be a check engine light with one or more stored EGR codes. More severe problems will produce noticeable driveability issues, and you may experience a rough idle or poor acceleration. These symptoms will tell you that your Prius is no longer operating at peak efficiency, so you should always have a qualified mechanic investigate them as soon as possible. Fortunately, repairing EGR problems usually isn't too costly or time-consuming. Your mechanic may be able to clean the valve to solve the problem. If the carbon build-up is too severe or the valve has mechanical issues, you'll need to replace it with a new one.

Keep these tips in mind when looking for Prius engine repair services near you.