Fuel economy can drop for many reasons, from low tire pressure to aggressive driving. However, one hidden cause often goes unnoticed until it creates bigger issues, such as a clogged catalytic converter. While this component is vital for reducing harmful emissions, it can also become a roadblock to your engine’s performance when it isn’t working properly.
If you’ve noticed sluggish acceleration, poor gas mileage, or a lingering check engine light, your catalytic converter might be to blame.
What the Catalytic Converter Does
The catalytic converter is part of your exhaust system. Its job is to take toxic gases produced by your engine and convert them into less harmful emissions before they leave the tailpipe. It works using a combination of heat and precious metals like platinum and palladium to create a chemical reaction.
When the converter is clean and operating as it should, exhaust gases flow freely through it. But over time, it can become clogged with carbon deposits, oil residue, or melted internal components, especially if there are underlying engine issues like misfires or oil burning.
How It Affects Your Gas Mileage
A clogged catalytic converter creates a bottleneck in the exhaust system. This backpressure forces your engine to work harder just to move air through the system. As a result, your engine may use more fuel to maintain the same performance, leading to a noticeable drop in fuel efficiency.
Your car might still run, but you’ll likely find yourself filling up more often and wondering why.
Warning Signs of a Clogged Converter
Most drivers don’t think about the catalytic converter until the check engine light comes on. But in many cases, the warning signs show up gradually:
- Reduced fuel economy despite no changes in your driving habits
- Sluggish acceleration, especially when merging or climbing hills
- A strong sulfur or rotten egg smell from the exhaust
- Check engine light, often related to oxygen sensor readings
- Overheating under the car, especially near the converter
Some of these symptoms can also indicate other engine problems, so it’s important to get a proper diagnosis from a shop that can read fault codes and inspect the converter’s condition.
What Causes a Converter to Clog
Catalytic converters are built to last a long time, often over 100,000 miles, but they’re not immune to damage. Some of the most common causes of clogging include:
- Unburned fuel reaching the converter due to a misfire or failing spark plugs
- Oil or coolant leaks into the combustion chamber
- Using the wrong type of fuel or additives
- Physical damage from impact or excessive heat
Addressing engine issues early can help protect your converter and extend its lifespan.
Can You Clean or Fix a Clogged Converter
Some drivers try fuel additives or “catalytic converter cleaners” to solve mild clogging. While these products may help remove light carbon buildup, they often don’t work on fully blocked or damaged converters.
In most cases, a clogged or failing converter needs to be replaced. It’s not a small repair, but it can restore performance, fuel economy, and emissions compliance, especially if the root cause of the failure is also addressed.
Don’t Ignore Fuel Economy Problems
It’s easy to blame poor mileage on weather, traffic, or even driving habits. But when your vehicle suddenly starts using more fuel, it’s worth getting it checked out. A failing catalytic converter not only affects gas mileage but also poses a risk to your engine’s health and your ability to pass emissions inspections.
Driving with a severely clogged converter can lead to engine overheating, stalling, or even internal damage in extreme cases. If you suspect something’s wrong, the safest move is to get a diagnostic inspection as soon as possible.
Catalytic Converter Service in Clifton Park, NY
At Gil’s Garage Inc in Clifton Park, NY, we inspect, diagnose, and replace catalytic converters using accurate testing and expert service. If your fuel economy is dropping or your check engine light is on, we’ll help you get to the root of the issue.
Let our team keep your car running clean, smooth, and efficient—schedule your appointment today.