Very few car parts last for the entire life of a vehicle, but a catalytic converter attached to a properly running engine can last for years. As part of the vehicle’s exhaust system, the catalytic converter uses heavy metals to chemically react with exhaust gases and reduce the number of harmful pollutants entering the atmosphere. When a catalytic converter begins to fail, it can negatively impact engine performance, fuel efficiency, and emissions compliance, potentially preventing your vehicle from passing an emissions test or being registered for on-road use.

 

What Are the Warning Signs?

If your vehicle exhibits one or more of these symptoms, then your catalytic converter may need to be replaced. Please note that these signs can overlap with other engine or exhaust system issues, so proper diagnosis done with an experienced professional is important.

  • Check Engine Light
    • If you have a 1996-or-newer (OBDII) vehicle, a check engine light may indicate a problem with your catalytic converter. A diagnostic scan tool plugged into the OBDII port under the dash may show a P0420 or P0430 code, which are commonly related to catalytic converter performance.
  • Sulfur Smell
    • If you smell rotten eggs when your vehicle is running, then the catalytic converter may not be catalyzing the sulfur in the exhaust gas. In other words, the catalytic converter might not be properly processing sulfur in the exhaust.
  • Emissions Test Failure(s)
    • A failing catalytic converter may be unable to reduce emissions to legally acceptable levels, resulting in a failed inspection.
  • Exterior Discoloration
    • Excessive heat can cause visible discoloration, such as a "glowing red" color. This color change is often an indicator of internal overheating.
  • Sluggish Acceleration
    • Oil, antifreeze, or too-rich fuel mixture are entering the exhaust, causing heat-related engine problems or a restriction on engine power and throttle response.
  • Decreased Fuel Economy
    • Poor flow in the exhaust system can cause the engine to strain itself, increasing fuel consumption and non-optimal performance.
  • Hard-Start/No-Start Engine Condition
    • In severe cases, exhaust restriction can interfere directly with engine operation or performance.

 

At-Home Diagnosis

If one or more of the warning signs are present, then a couple of preliminary tests may help identify a catalytic converter issue. If you don’t have the tools or the inclination, then an auto repair/muffler shop, dealer or mechanic can perform these tests for you.

Exhaust Temperature Test: Once the engine is up to normal operating temperature, measure the exhaust temperature directly, before and after the converter, using an infrared thermometer. A significant temperature difference, typically 100°F or more, may indicate the converter needs to be replaced. A large temperature difference can result from a clogged converter that traps exhaust gases, thus rendering it less efficient.

Engine Vacuum Test: If there is no check engine light on or your vehicle was built before 1996 (pre-OBDII), then an engine vacuum test may be necessary if there are other warning signs. When the engine is idling, hook up a vacuum gauge to the intake manifold and record the reading. Then, rev the engine to 2,500 RPM (a helper will make this easier) and observe the measurement again. If the gauge doesn’t return to a similar reading as it showed when idling or it is very slow to do so, a failing converter may be a contributing factor.

 

Find The Right Catalytic Converter

As mentioned in our guide on the different types of catalytic converters article, depending on your experience level and access to tools, you may be able to replace it yourself. Many vehicle owners can replace a catalytic converter themselves, especially when using a MagnaFlow direct-fit catalytic converter, which is designed to bolt directly into place with no modification. However, be honest with yourself about your mechanical ability before attempting a do-it-yourself installation. Incorrectly installing a catalytic converter can result in other engine problems and prevent the vehicle from passing emissions testing.

To find the right catalytic converter for your vehicle, use MagnaFlow’s Shop by Vehicle tool. Have questions? Give us a call at 1-800-990-0905 and we’d be happy to help.