The 6 Things That Make Your Car's Exhaust System Work By Carlsen Subaru, Serving San Francisco

Things to Know About Your Vehicle's Exhaust System - Service Questions Answered by the pros at Carlsen Subaru

May 17, 2019

You may recognize the exhaust system in your vehicle as that pipe at the back, but did you know that there's a lot more to a car's exhaust system? You may already know that a gas-powered engine works by igniting a mixture of fuel and air to create explosions in the engine's cylinders. The resulting force of these explosions is harnessed to power your car. However, what's left over in the cylinder after the explosion must be cleared out every time. That's where the exhaust system comes in to keep everything safe and clean. Below, we go through the six main parts of an exhaust system starting at the engine's cylinders.

In our authorized Subaru service center at Carlsen Subaru, our factory-trained technicians have a vast amount of experience with all things Subaru. That includes the exhaust systems, and we think every customer is best served when they have good information about their vehicle. If you have any questions about your Subaru, we'd be happy to chat with you over the phone, online, or in person at 480 Veterans Blvd, Redwood City, CA 94063.

Assortment of damaged or worn engine intake and exhaust valves.

6. Engine Exhaust Valves

Once the spark plug has ignited the mixture of fuel and air inside an engine's cylinder, the resulting force drives the piston down. As the piston travels back up in the cylinder, the exhaust valves in the cylinder head are opened to allow what's left of the combustion process to be evacuated from the cylinder. A stuck exhaust valve can cause serious problems for how your engine runs.

Car exhaust manifold on white background.

5. Engine Exhaust Manifold

This part of your engine's exhaust system is bolted to the cylinder head so that all the exhaust gases can be collected and directed into one, or sometimes two, pipes. The exhaust manifold is typically a single piece of metal with no moving parts, so it's rare to have issues with it. However, if an engine isn't running correctly, this manifold can warp and cause exhaust to leak into the engine compartment. In some cases, this can even cause exhaust to get into the passenger cabin of the vehicle. A trained technician can usually identify such an exhaust leak by ear, and be sure to have this problem repaired immediately.

4. Upstream O2 Sensor

This is one of the most important sensors on modern, fuel-injected engines. That's because this sensor measures the amount of oxygen that's in the exhaust gases. The car's computer takes this information and adjusts the timing of the spark along with how much fuel and air is allowed into the cylinders. If this sensor goes bad, you can usually count on the check engine light coming on and there's a good chance that the engine will run poorly or not at all. Replacing this O2 sensor is a common service for higher-mileage vehicles, and it's typically a quick and easy car repair to have done at a factory-authorized service center like ours at Carlsen Subaru.

Closeup of check engine light spelled out in red.

3. What Does A Catalytic Converter Do?

The next part of the modern car exhaust system is the catalytic converter, which is sometimes called the Cat. This is a particularly important part that's necessary for cleaning the exhaust before it's expelled into the atmosphere. A catalytic converter works with a catalyst that breaks apart harmful molecules into their less-harmful components. For instance, nitrous oxide is broken apart into nitrogen and oxygen. The Cat gets exceptionally hot inside, which also helps it burn unused fuel that contains hydrocarbons. When a catalytic converter is working properly, the only thing that should be coming out of your car's tailpipe is nitrogen, carbon dioxide, and water vapor.

2. Downstream O2 Sensor

Most modern vehicles have another oxygen sensor behind the catalytic converter. This is there to help you know when the catalytic converter is no longer working as it should, and it's similar to the upstream O2 sensor. However, the computer won't use information from this downstream sensor when determining how to run the engine. If this second sensor goes bad, or the Cat isn't working properly, you can expect the check engine light to come on.

1. The Resonator & Muffler

Most modern vehicles have both a resonator and a muffler. Ultimately, each of these parts are there to reduce the sound of the engine when running. The main difference is that a muffler is designed to reduce noise across all speeds that the engine may run at, and the resonator is designed to address the resonance that occurs at certain engine speeds.

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  1. Carlsen Subaru

    480 Veterans Blvd
    Redwood City, CA 94063

    • Sales: (888) 520-5916

Carlsen Subaru

480 Veterans Blvd
Directions Redwood City, CA 94063

  • Sales: 650-365-6390
  • Service : 650-365-6390
  • Parts: 650-365-6390
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