How To Tell If Your Catalytic Converter Is Clogged (Before It’s Too Late)

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The catalytic converter is a non-serviceable part that may last well beyond 100,000 miles; or, in some cases, all the lifetime of the vehicle, provided the engine receives proper care. Contained in the cat converter (or just “cat”) is a honeycomb structure of precious metals, including rhodium, platinum, and palladium, which is the goal of thieves and is why cat converter theft continues to make headlines. Those metals convert toxic exhaust gases, corresponding to carbon monoxide, lead, and nitrogen dioxide, into much safer carbon dioxide and water, helping lower emissions on the tailpipe.

Nonetheless, the catalytic converter can get clogged after a few years of use and abuse. Probably the most noticeable symptoms include hard starting, mediocre acceleration, engine misfires, lackluster fuel economy, failed emissions tests, and an illuminated check engine light accompanied by P0420 or P0430 error codes. One other symptom is a sulfuric exhaust smell or a powerful aroma of rotten eggs, which can indicate that the cats are clogged or are chemically degrading.

The excellent news is that a clogged catalytic converter doesn’t necessarily mean that the catalysts are going bad. The bad news is that clogged cats will cause more exhaust backpressure, which is able to hinder engine performance and eventually result in overheating and other costly damage. It’s why you should address a nasty or clogged catalytic converter ASAP before it causes more problems afterward.

Despite its status for durability and longevity, the catalytic converter can fail, wear out, or get clogged inadvertently way sooner than its intended lifespan. Defective spark plugs may cause misfires, allowing more unburned fuel to achieve the exhaust and catalytic converter, which results in particle buildup and eventual blockage. It’s why changing the spark plugs at the right intervals helps prevent early wear of the catalytic converter.

Meanwhile, a dirty air filter may cause a richer air-fuel mixture, which allows unburned fuel to achieve the exhaust. A leaking head gasket can allow oil or coolant to enter the combustion chamber, producing dirtier exhaust gases. When this happens, the catalyst can get clogged or permanently damaged. Moreover, contaminants from substandard gasoline can burn through the exhaust and coat the catalyst with soot and particulate matter.

In some cases, the honeycomb substrate can break down as a result of wear and aging, allowing broken pieces of the catalyst to migrate towards the tailpipe, which may cause further blockages and backpressure. At that time, you may notice rattling sounds or loud, hissing noises coming from under the automotive when accelerating, indicative of excess backpressure and severe clogging.

A clogged catalytic converter doesn’t mean your automotive is heading to the scrap heap. On the other hand, you will need to find out if the cats are only clogged, or have deteriorated to the purpose of needing an expensive alternative. The latter will cause a big dent in your budget, as replacing a catalytic converter can cost between $300 and $2,500 before labor charges, depending on the vehicle and engine size.

Once the check engine light activates and the P042 or P043 error codes are present, your first recourse is to make use of fuel additives and hope they work in cleansing the catalyst. Products just like the Cataclean Fuel & Exhaust Cleaner and Motor Power Care Catalytic Converter Cleaner are relatively low-cost and simple to make use of. Pour the contents into your automotive’s fuel tank (full of at the least half a tank of fuel) and drive normally, allowing the product to work its magic.

You can too remove the catalytic converter, soak it in degreaser overnight, and pressure wash with clean water. Nonetheless, this isn’t a DIY fix, and would require the care and expertise of knowledgeable mechanic. If the catalysts are mildly clogged and are causing the check engine light to activate, using a cat cleaner might do the trick. Prepare yourself for the worst if the honeycomb substrate is burnt or has broken into chunks, which necessitates a costly alternative of all the catalytic converter.