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What Causes a Catalytic Converter to Fail?

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What Causes a Catalytic Converter to Fail?

Since there are no moving parts on a catalytic converter, you would expect that they would be fairly durable and long lasting and they are but, in spite of all of the advancements in catalytic converter technology, they still fail. At Viper Motorsports in Weatherford, Texas, we install replacement catalytic converters almost every day. Many times, catalytic converter failure is a symptom of an issue somewhere else in the vehicle.

It is imperative that you fix the problem that caused your OEM catalytic converter to fail because if you don't, that same problem will likely destroy the replacement converter as well. The warranty that comes with a new replacement catalytic converter will not cover the type of damage listed below.

If your factory installed catalytic converter needs to be replaced, one of the problems below most likely contributed to its failure.

Engine Tune-Up Required
Engines in need of service and older engines that burn oil due to worn cylinder walls, stuck rings, and worn valve guides will produce by-products that can foul the converter. When an engine is operating outside of the proper specifications, wear and damage may be caused to the catalytic converter as well as the engine itself. Incorrect air/fuel mixture, incorrect timing, or misfiring spark plugs could lead to a catalytic converter failure or worse.

Bad Spark Plugs or Spark Plug Wires
Spark plugs that don't fire or misfire forces unburned fuel into the exhaust system. Because the catalytic converter gets very hot, this unburned fuel can ignite inside the converter and could result in a partial or complete melt down of the ceramic catalyst.

Oil or Antifreeze Entering the Exhaust System.
When oil or antifreeze makes its way into your exhaust system creates a thick carbon and soot which coats and eventually clogs the air passages in the converter's ceramic honeycomb catalyst. This causes two separate problems. First, these carbon deposits stop the catalytic converter from doing its job of removing harmful emission in the exhaust flow. Second, When the pores become clogged in the ceramic catalyst, exhaust flow is restricted which increases backpressure. This results in heat and exhaust backing up inside the engine. The excess back pressure created can actually cause internal engine damage. Your engine can actually pull burnt exhaust gasses back into the combustion chambers and reduce the efficiency of the next burn cycle and creating a loss of power and overheating of engine components. Worn out piston rings, failing gaskets, faulty valve seals or even warped engine components are all possible causes of this problem.

Unburned Fuel Entering the Exhaust System.
Ideally, the fuel that powers your vehicle is burnt up in the combustion chamber. Any fuel that gets through the combustion chamber unburned enters the exhaust system and can ignite once it reaches the catalytic converter. This can over-heat the converter far beyond its normal operating limit. and cause a Melt Down. Possible causes are an improper fuel mixture, incorrect timing, bad spark plugs, a malfunctioning oxygen sensor, sticking float, defective fuel injector or a faulty check valve.

Oxygen Sensor Not Functioning Properly.
If your oxygen sensor is no functioning properly it can send incorrect readings of exhaust gasses to the vehicle's computer. The faulty sensor readings can result in a improper (too rich or too lean) fuel mixture condition. Too rich and the catalyst can melt down from fuel burning inside the converter. Too lean and the converter will not be able to serve its purpose changing hydrocarbons into safe elements. This may cause your vehicle to fail the emissions test during the annual State Vehicle Inspection.

Road / Structural Damage
The catalyst honeycomb inside of a catalytic converter is made up of a lightweight, thin-walled, fragile ceramic material. It is wrapped in a dense, insulation mat. This mat holds the catalyst in place and provides some protection against damage. However, broken exhaust hangers, off-road driving , potholes, speed bumps or any impacts underneath your vehicle can strike the catalytic converter causing a catalyst fracture. Once the ceramic honeycomb is fractured, the broken pieces rattle around breaking up into smaller pieces. As a result, exhaust flow is interrupted and backpressure in the exhaust system increases leading to heat buildup and loss of power. Corrosion, thermal shock, metal fatigue, stress fractures and stripped oxygen sensor threads are some other issues that may require you to need a replacement catalytic converter.

Short Trips
If you gennerally only take short trips around town in your vehicle and dont regularly drive long distances, your catalytic converter may not be getting hot enough to completely burn away the hydrocarbons. To prevent clogging the catalytic converter, take your vehicle for the occasional highway drive for 15 minutes or more. This will allow the exhaust to sufficiently heat up and burn off all of the deposits builtup in the catalytic converter.

If your catalytic converter is in need of replacement call on the professional exhaust technicians at Viper Motorsports in Weatherford, Texas. We'll replace your old converter and inspect it to determine the original cause of the failure. We can also help you resolve the underlying problem. (817) 609-8001

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Address: 902 Fort Worth Hwy
Weatherford, TX 76086
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