Symptoms of a Bad Catalytic Converter

bad Catalytic Converter Symptoms

What are the symptoms of a bad or plugged catalytic converter? Common failures include: Low engine power, check engine light, failed smog test and more. A catalytic converter is designed to remove harmful gasses from the air. This unit is positioned in the exhaust system just behind the exhaust manifolds and can fail in one of three ways. First, the catalytic material can simply wear out and loose its effectiveness. The second is the material can melt due to extreme temperatures which makes the converter plug. And finally, the honeycomb material can break apart and leave the cat converter empty with absolutely no cleaning affect to the engine exhaust.

Is it Safe to Drive?

There are different levels of failure which must be considered before you can make a decision if your car is safe to drive or not. The following list with help you decide whether or not you can drive your car with a bad or clogged catalytic converter depending on the problem you are having.

1. Low Engine Power

The catalytic converter is part of the exhaust system and when it goes bad it can cause restricted exhaust flow. Your car's engine depends on a free flowing exhaust system to maintain its power output. In the early stages of a failure the catalyst material inside the catalytic converter can start to melt and cause partial blockage causing poor engine acceleration and performance. There are many stages of this blockage which will greatly vary. It will usually start to be noticeable under heavy engine load and slowly loose more and more power. You can test the catalytic converter yourself if you would like to see if this could potentially be a problem or not.

plugged catalytic converter

2. Check Engine Light

When a catalytic converter stops working or becomes weak it will allow increased emissions to be omitted from your cars the tail pipe which increases our air pollution. Your car is equipped with two oxygen sensors, a primary and secondary unit which are positioned before and after the cat converter. These sensors monitor the incoming and outgoing gases and send feedback information to the computer. If the catalytic converter is not doing it job the computer will trigger a check engine light letting you know there is something wrong.

3. Failed Smog Test

The material inside the catalytic converter is a elongated honeycomb coated with a chemical designed to heat up when exposed to the engine exhaust. Over time this chemical will loose its effectiveness allowing a downgrade of its ability to converter unspent fuel into spent fuel in the exhaust system. The local smog station or check center is put in place to check this performance and will require a replacement if the catalytic converter if it is found to be weak or ineffective.

4. Engine Not Starting

It is possible that when the material inside the catalytic converter can break apart and completely block the outlet of the exhaust system not allowing air to enter the engine causing it not to start. This blockage can be intermittent and will happen while driving. Once the engine stalls it can start back up as the blockage falls away from the outlet until you hit a small bump which it is again pushed back into the outlet.


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