What does it mean when your catalytic converter glows red?

While catalytic converters can serve your car for decades, sometimes, they can glow red, resulting in poor engine performance and, ultimately, engine shutdown.

With our experience with cars for more than two decades, we have compiled this guide to ensure you understand the potential problem facing your car. However, we do advise visiting your mechanic immediately after you notice the problem to avoid incurring huge replacement costs. Read on to learn more about catalytic converters.

How Does A Catalytic Converter Work?

Before delving into why a catalytic converter glows red, it is essential to understand how it operates when it’s not faulty and why it does so. The catalytic converter, typically a large metal box, is located on the vehicle’s underside. It has two pipes projecting from it, the input and output, and the catalyst to prepare the gasses for release.

The catalytic converter works like a cycle where, when an engine generates harmful pollutants, the cat uses a catalyst-containing chamber to convert them into innocuous gasses such as steam. It separates harmful components from the vehicle’s emissions before their release into the atmosphere.

The gasses from the input pipe, which is connected to the engine, are blown over the catalyst, which initiates a chemical reaction that breaks down pollutants. Once the gasses are safe, the second pipe output, which is attached to the car’s exhaust, carries the less hazardous gasses and releases them out to the environment.

Suggested Read: Will catalytic converter reduce exhaust smell?

What Is The Normal Operating Temperature Of A Catalytic Converter

Under typical operating conditions, the average working temperature of a vehicle’s catalytic converter may be 750 degrees Fahrenheit. However, the temperatures may rise upwards of 1,200 to 1,600 degrees Fahrenheit under extreme load conditions.

If one or more cylinders are not functioning correctly and unburned fuel enters a catalytic converter, temperatures can reach 2000 degrees Fahrenheit.

Reasons Why A Catalytic Converter Is Glowing Red

When the cat’s temperature rises to over 2000 degrees Fahrenheit to a point where the cat becomes red, this indicates a major fault and could result from several things. These include:

ECU (Engine Control Unit) Failure

Cars do experience wear and tear, especially with prolonged use. This is why you may encounter issues such as ECU failure.

When there’s an ECU failure in your car, often this will lead to an excessively rich mixture of fuel. However, while this can be an issue, it may not warrant replacing the ECU. Check if the wire harness is the issue, and work on that.

An Engine Control Unit is replaceable. However, this might be challenging. First, you need an expert to carry out the replacement. 

Second, ECUs aren’t cheap, so you have to pay a good amount to get the right quality.

So, instead, check and replace the car’s wire harness, which costs much less. Failure to replace a faulty wire harness can land you in lots of trouble, including engine misfiring.

An Engine Issue

When an engine operates outside the recommended parameters, both the catalytic converter and the engine are susceptible to wear and damage. For instance, if an underlying engine problem causes unburned fuel to reach the catalytic converter, the device could glow red due to the high heat.

If the issue is not addressed on time, you may be forced to replace both the engine and the cat.

Clogged Cat

Any malfunctioning part of the car that’s directly or indirectly connected to the cat is a potential culprit to the clogging of the cat. For example, worn valve guides, cylinder walls and clogged rings will generate byproducts that might clog the converter.

Learn More: Will A Clogged Catalytic Converter Cause Your Car To Lose Power?

Bad Plug

The main reason why the catalytic converter is glowing red is that it is receiving unburnt fuel from the engine. The most common cause of this is a faulty spark plug. If the plug fails, there will be no combustion in that cylinder, and fuel will exit the exhaust pipe in its unburned state.

If this is the problem, the spark plugs can be replaced if you are able to address the issue on time, but if you wait until the catalytic converter melts, your only option will be replacing the plugs, which are on the pricier side.

Excessive Fuel Pressure

Another cause of a red catalytic converter is excessive fuel pressure. You may notice power loss because the fuel regulator is failing. Another issue might be a faulty fuel injector in your car.

The best way to ensure this is to carry out a fuel pressure test. Check the fuel rain in your car for a  test port. Once you find it, plug in the gauge and take note of the pressure reading.

Faulty Ignition Coil

Car models like VW and Audi tend to experience instances of faulty ignition coil. This might be the reason you come across a red catalytic converter.

If you suspect your vehicle has a faulty ignition coil, you need an immediate replacement. Check each cylinder to see which ignition coil is the main culprit. A test will reveal the exact cylinder code so you can perform the replacement.

For example, P0301 means cylinder 1 is misfiring. This is the reason why your catalytic converter is super-ho. Replace the faulty ignition coil from the cylinder with a new one. Next, you must clear all codes using a code reader before starting the vehicle.

What Happens If You Don’t Fix The Catalytic Converter Soon Enough

If you keep driving a car with a faulty catalytic converter, in addition to having the engine light stay on till you fix the issue, here are a few challenges you will encounter.

You risk harming the engine, the exhaust, and the exhaust manifold. Replacing any of this won’t be a walk in the park and will cost you a handsome amount.

Your vehicle will also fail an emissions test. Bear in mind that a failed emission test means that you will need to have your car serviced or fixed before you can legally renew the registration and continue driving it. Fortunately, the law allows you a short grace period to drive the car before retaking the emissions test.

You will also realize a reduction in your car’s power since the ECU (Engine Control Unit) will adjust the timing and fuel-to-air ratio of the fuel mixture to compensate for the unexpected oxygen sensor values. This will impair the vehicle’s fuel economy and cause a loss of power, particularly during acceleration.

Suggested Article: Can I replace my catalytic converter with a straight pipe?

Actions You Should Take If Catalytic Converter is Glowing Red Hot?

All the reasons above can cause your catalytic converter to overheat. It’s important to eliminate them before you take a step to replace the converter.

A clogged catalytic converter can also lead to overheating. So, you can conduct an exhaust back pressure test to see if this is the case. It’s possible to purchase the right testing equipment from a muffler shop or visit an auto shop.

Once you have an exhaust back pressure test, unplug the upstream pressure sensor. Plug in the test gauge and proceed to start your car. The test will take a few minutes to show you the right results. If there is excess pressure in the catalytic converter, it indicates a blockage.

Any pressure above 20 kPa is a sign of trouble. You can note this by revving up the engine to 2000 RPMs.

Is It Safe to Drive My Car If the Catalytic Converter is Red Hot?

No. Never drive a car with an overheating catalytic converter. This can cause lots of safety issues for you and other motorists. Instead, contact an auto repair shop mechanic to come and fix this matter. Only after can you take the car back on the road.

How To Prevent The Catalytic Converter From Overheating

When properly taken care of, a catalytic converter will serve you for a long time. Here’s how to ensure you don’t experience any challenges with your car’s cat.

Never for long periods without driving the car. Assuming the vehicle isn’t your daily drive, you may dedicate at least one day in the week to go for a short drive. Preferably, go for a 20-minute drive at highway speeds to ensure you hit the optimal operating temperature.

Perform normal maintenance service, including oil changes, air filter replacements, and periodic inspections. To prevent damage to the catalytic converter, immediately address any issues you or your mechanic discover during the routine service.

Fix the check engine light immediately. A blinking check engine light signifies a significant internal malfunction that demands rapid intervention. Continuing to drive with the check engine light on could lead to more extensive and expensive repairs. 

For example, the engine is likely functioning in an open loop and not using feedback but rather programming. This means the engine may run too rich or too low in an open loop, damaging the catalytic converter.

Key Takeaways

• The catalytic converter’s temperature is 750 degrees Fahrenheit
• When the exhaust is filled with unburnt gasses, the cat will glow red
• Ensure you call the mechanic immediately after you notice the issue