You might be hearing strange sounds from your car or maybe it smells like rotten eggs. That could mean your catalytic converter is not working well. One simple way to test it is by using an infrared thermometer. In this article, I will show you exactly how to test your catalytic converter without removing it. I’ve done it myself, and it saved me time and money. You just need a little care and the right method. Let’s go step-by-step and get your car back in shape.
Understand What a Catalytic Converter Does
Before checking your catalytic converter with an infrared thermometer, it’s important to know what this part does in your car. The catalytic converter is part of your car’s exhaust system. It helps change bad gases from your engine into cleaner ones before they go out into the air. These gases include carbon monoxide, hydrocarbons, and nitrogen oxides. The catalytic converter turns them into safer gases like carbon dioxide and water vapor.
The converter gets very hot when the engine is running. It needs this heat to work properly. That’s why temperature is a big clue in knowing if it’s working or not. If the converter is not getting hot enough or gets too hot in the wrong places, it may be damaged or blocked.
Sometimes when a converter is bad, your car might lose power, use more fuel, or even make strange smells. If the converter is blocked, the engine can struggle to push the exhaust through. This can make your car feel slow or heavy when you drive. You might also see the “check engine” light come on.
If you ignore a bad catalytic converter, it can cause other parts of the car to break too. It’s also bad for the environment and can make your car fail emissions tests. That’s why it’s important to check it early.
Using an infrared thermometer is a safe and quick way to check the converter’s temperature. This will help you see if the inside of the converter is working right. You don’t have to take anything apart. You just check the temperature at two spots — the front and the back of the converter — and compare them.
If the back is hotter than the front, the converter is usually working well. But if both spots are the same, or if the front is hotter, there might be a problem. That’s the key to testing it with a thermometer.
- The catalytic converter changes harmful gases to cleaner ones
- It needs high heat to work well
- A damaged converter can cause strange smells and engine problems
- It helps your car pass emission tests
- Checking its temperature helps know if it’s working
- Infrared thermometers are quick and safe to use
- Comparing front and back temperatures gives a clear result
Get the Right Tools for the Job
To test your catalytic converter with an infrared thermometer, you need the right tools and a safe space. This makes sure you don’t get hurt and your test works properly. The good news is you don’t need a lot of expensive things.
The most important tool is an infrared thermometer. This is a handheld device that shows temperature when you point it at something. You don’t have to touch anything hot, which keeps you safe. You can buy this tool online or at auto parts stores. Make sure it can read temperatures over 1000°F, because converters can get that hot.
You will also need safety gloves, glasses, and something to lift your car if needed. If your car sits low, you might need a jack and jack stands to lift it up. Never go under a car that isn’t safely supported. Safety always comes first.
Some people also like to have a notepad or phone to write down the temperatures they check. This can help if you want to compare or ask a mechanic later. Make sure your car has been running for a few minutes before the test. This warms up the converter, which is important for checking if it’s working right.
Here’s a short list of what you need:
- Infrared thermometer
- Gloves and safety glasses
- Car jack and stands (if needed)
- Notepad or phone to write results
- A safe and flat place to park your car
Always read the thermometer manual before using it. Each model works a little different. Some have laser pointers to help you aim at the right spot. Others show the temperature fast, so you don’t need to wait.
Make sure your thermometer is working properly before starting. Check it by aiming at something like boiling water (carefully) or a warm engine part to see if it gives a real reading.
- Get a thermometer that reads high heat
- Always wear safety gear when working near hot parts
- Warm up your car first before testing
- Use jack stands if you need to lift the car
- Write down your temperature results
- Test your thermometer before using it
- Aim carefully at the right spot for a correct reading
Find the Converter and Get Ready for Testing
The next thing is to find the catalytic converter on your car. It is part of the exhaust system and is placed under your car, usually near the middle or closer to the engine. It looks like a metal can with pipes going in and out of it. Most converters are easy to spot because they are bigger than the pipes and often have a heat shield over them.
To get ready for the test, park your car on flat ground and make sure the engine is warm. Let it run for about 10 to 15 minutes before you begin testing. This gets the converter hot enough to give a good temperature reading.
If your car is low to the ground, lift it safely using a jack and place it on jack stands. Never slide under a car that is only on a jack. You might not need to get under the car if the converter is easy to reach from the side.
Once the car is ready, grab your infrared thermometer and safety gear. Keep your hands and face away from hot parts. Engines and exhausts can stay hot even after the car is turned off, so always be careful.
Take a quick look at the converter for signs of damage. If it looks cracked, bent, or covered in black soot, that could mean something is wrong. You can still test the temperature, but make a note of anything strange you see.
Use a flashlight if needed to see clearly. Sometimes the converter is hidden behind shields or pipes, so take your time and look closely.
You’ll need to test two spots on the converter:
- The front part, where the exhaust enters
- The back part, where the clean gases exit
These are the most important points for your test.
- Find the converter under the car
- Let the engine run for 10-15 minutes
- Wear gloves and use a flashlight if needed
- Check for visible damage or signs of trouble
- Lift the car safely if needed
- Know where the front and back of the converter are
- Be careful around hot engine parts
Use the Infrared Thermometer the Right Way
Now it’s time to start the test. Hold the infrared thermometer in your hand and aim it at the first spot — the front of the catalytic converter. This is the side where the exhaust gases go in. Keep your hand steady and press the button to get a reading. Write down the temperature.
Next, move to the back of the converter. This is the side where the gases come out. Do the same thing — aim the thermometer, press the button, and read the number. Write it down too.
Now compare the two temperatures. If the back is hotter than the front by at least 100°F (sometimes even more), your catalytic converter is working well. This means it is burning the bad gases and doing its job.
If the temperatures are the same or if the front is hotter, then something may be wrong. It could mean that the converter is clogged or not working inside. This is a sign that you should have it looked at by a mechanic or think about replacing it.
Make sure you test when the engine is hot and running at idle. Do not test it after turning the engine off. If you turn off the engine, the temperature may drop fast, and the results won’t be right.
Some tips for better testing:
- Always point the thermometer directly at the surface
- Do not stand too far or too close
- Avoid testing in windy or cold weather if possible
- Try to do the test in a closed garage or calm area
- Use the laser pointer on your thermometer (if it has one) to aim better
- Test both front and back of the converter
- Back should be hotter than the front
- Check when engine is warm and running
- Write down your readings to compare
- Use laser for better aim if your tool has one
- Do not test right after turning the car off
- If front is hotter, the converter may be blocked
Understand the Test Results
Reading the temperatures is only part of the job. Now you need to understand what those numbers mean for your catalytic converter. This is where you can tell if everything is good or if there’s a problem.
If the back part of the converter is hotter than the front, that means the converter is heating the gases like it should. The difference in temperature should be around 100°F or more. That’s a good sign.
If the two temperatures are very close or the front is hotter, then the converter might not be working. That could mean it’s clogged or the inside parts are damaged. A bad converter can’t change the gases, and this shows up in the test results.
Also, if both sides are very cold even after running the engine, it might mean the converter is completely blocked or that the engine is not running right. Either way, it’s a problem that needs attention.
Sometimes the results might not be clear. If you’re not sure, try testing again after a short drive. A 10-minute drive at normal speed can make the converter hotter and help you see better temperature differences.
Keep in mind, other things can also affect the test:
- A cold engine will give low readings
- A misfiring engine can hurt the converter
- Exhaust leaks can change the results
- If your check engine light is on, check for trouble codes
Use your notes and compare them with known working temperatures. Most good converters will show a back temperature of around 600°F to 900°F, while the front might be 400°F to 700°F.
- Back hotter by 100°F or more means working well
- Same or front hotter means it could be blocked
- Cold readings may mean engine or converter issue
- Try testing again after a short drive
- Check for engine trouble or leaks if results are odd
- Write down all numbers for future checks
- If unsure, ask a mechanic for help
What to Do if the Converter Fails the Test
If your catalytic converter fails the test, don’t worry too much. There are steps you can take to fix the problem or decide what to do next.
First, check your notes again and make sure the test was done right. Did the car run long enough before testing? Did you aim the thermometer correctly? Try to double-check your process and test again to be sure.
If the converter still fails the second test, then you know something is wrong. A failed converter usually means it’s either clogged or broken inside. Sometimes you can clean it using special fuel additives or by doing an “Italian tune-up” — which means driving the car at higher speeds for 15–20 minutes to burn off buildup.
But if it’s too far gone, you’ll need to replace it. Replacing a converter can cost a lot, depending on your car. Before you do that, check if the engine has other problems. Sometimes bad spark plugs, oil leaks, or rich fuel mixtures can damage the converter. Fixing those things first can save you from needing another new converter later.
Also, check your car’s warranty. Some cars have a long warranty on emission parts like the converter. You might get it fixed for free.
- Test again if you’re unsure
- Use fuel cleaners to try cleaning it
- Try a short high-speed drive to burn off buildup
- Look for engine problems that may cause converter failure
- Replace it only if cleaning doesn’t help
- Check your warranty before buying a new one
- Ask a trusted mechanic if you need help
Final Thoughts
Testing your catalytic converter with an infrared thermometer is a smart and easy way to find out if it’s working or not. You don’t need to take anything apart or spend too much money. Just warm up your car, point the thermometer, and compare the front and back temperatures. If the back is hotter, your converter is doing its job. If not, it might need help or replacement. Always take care of your car early, and it will keep running better for longer.
Frequently Asked Questions (FAQs)
Is it safe to use an infrared thermometer near a hot engine?
Yes, it is safe if you are careful. Always wear gloves and keep your hands away from very hot parts. Infrared thermometers are made to measure heat without touching. Just make sure your car is on flat ground, and you aim the thermometer properly. Don’t rush the process, and avoid leaning too close to the engine or exhaust parts while the car is running. If you’re not sure where to aim, use a flashlight and move slowly. Always follow the safety steps and take your time.
Is it normal for both ends of the converter to have close temperatures?
No, it is not normal. If both the front and back of the catalytic converter have nearly the same temperature, it usually means the converter is not working right. The converter should heat up the gases, so the back should be hotter. If there’s no big difference, it might be clogged or damaged inside. Try testing again after a short drive. If the result is the same, you may need to clean or replace it. Sometimes other engine problems can also cause this, so it’s good to check everything.
Can I test the catalytic converter without lifting the car?
Yes, you can if your converter is easy to reach from the side of the car. Many converters are close to the front underbody or behind the front tires. Use a flashlight to check where it is before you start. If your car is very low or the converter is hidden, you might need to lift it using a jack and stands. Always make sure the car is parked on flat ground and the wheels are blocked so it doesn’t move. Safety should always come first.
Can a dirty catalytic converter be cleaned?
Sometimes yes. A catalytic converter that is slightly clogged can be cleaned using special fuel system cleaners. These are added to the gas tank and help clean carbon buildup over time. Another way is to drive the car at higher speeds for 15–20 minutes to burn off the dirt. This is sometimes called an Italian tune-up. But if the converter is badly damaged or totally blocked, cleaning may not help. In that case, it will need to be replaced. Always check the engine too, because engine problems can cause the dirt.
Do I need to replace the converter if the test fails?
Not always. A failed test could be due to a small issue that you can fix. Try cleaning the converter or running the car at higher speeds to see if it improves. Also, check your engine for things like bad spark plugs, oil leaks, or too much fuel. These things can make the converter dirty or stop working. If the converter is broken inside or completely blocked, then it must be replaced. Check your warranty first. You might not have to pay for the replacement if your car is still covered.
Is it expensive to replace a catalytic converter?
Yes, it can be. The price depends on the car model and the type of converter. Some can cost a few hundred dollars, while others can be more than a thousand. Labor costs are also added if a mechanic does the work. Before replacing, try cleaning it or fixing other engine issues. Also, check your car’s warranty. Many cars have long-term warranties on emission parts, and the converter might be replaced for free. Always get a second opinion if the price seems too high.
Do I need a mechanic to test the converter?
No, you can do the test yourself using an infrared thermometer. It is a simple test if you follow the steps. You just need to warm up the engine, aim at the right spots, and read the temperatures. Make sure to stay safe and wear gloves. But if you’re unsure about the results or if the converter is hard to reach, it’s okay to ask a mechanic. They can confirm your test and tell you what to do next. Doing the first test yourself can still save you time and money.
Can a bad converter make my car slow?
Yes, it can. A clogged or damaged catalytic converter can stop exhaust gases from moving out of the engine. This makes the engine work harder, and your car may lose power or feel slow when driving. You might also notice bad fuel mileage, strange smells, or the check engine light coming on. If your car feels heavy or slow to respond, testing the converter is a good idea. Fixing or replacing a bad converter can make your car run better and save fuel too.