* Rich Air/Fuel Mixture: This is the most common cause. If the engine is running too rich (too much fuel relative to air), unburned fuel enters the catalytic converter. When this fuel ignites inside the converter, it generates significant heat. Several things can cause a rich mixture:
* Faulty Oxygen Sensor(s): These sensors tell the computer how much oxygen is in the exhaust, allowing it to adjust the air/fuel ratio. A bad sensor can lead to inaccurate readings and a consistently rich mixture.
* Mass Airflow Sensor (MAF) Issues: The MAF sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor will provide inaccurate data, leading to an incorrect fuel delivery.
* Fuel Injectors: Clogged or leaking fuel injectors can deliver too much fuel.
* Fuel Pressure Regulator: A faulty regulator could lead to excessive fuel pressure.
* Computer Issues (PCM/ECM): Problems with the engine control module can result in incorrect fuel delivery calculations.
* Exhaust Restriction: A blockage downstream of the catalytic converter (e.g., severely clogged muffler, damaged exhaust pipe) can restrict exhaust flow. This forces exhaust gases to back up, increasing pressure and temperature within the converter.
* Internal Converter Issues: Although less likely to cause the *initial* cherry-red glow, a partially clogged or damaged converter can contribute to the problem once other issues are already present. The increased backpressure from a partially blocked converter would exacerbate a rich mixture issue, for example.
* Ignition System Problems: While less common, misfires can send unburned fuel into the converter, leading to excessive heat.
What to do:
This isn't something to ignore. A cherry-red catalytic converter is a serious problem. Do not drive the truck until the cause is identified and fixed. Continued operation could lead to converter failure, fire, or damage to other parts of the exhaust system.
You should have a qualified mechanic diagnose the problem. They will likely use a scan tool to check for diagnostic trouble codes (DTCs) from the engine control module and perform tests to check the oxygen sensors, MAF sensor, fuel injectors, and other potential causes. They'll also inspect the exhaust system for restrictions. Ignoring this could lead to costly repairs down the line.
