All car manufactures are required to equip their cars with at least one oxygen sensor and a catalytic converter to monitor the exhaust gasses, analyze them and correct them from harmful to less harmful gasses before emitting them into the atmosphere. A catalytic converter is an exhaust emission control device that reduces toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants by catalyzing a redox reaction (an oxidation and a reduction reaction).
Catalytic converters are usually used with internal combustion engines fueled by either gasoline or diesel. A catalytic converter is found in the exhaust system of an internal combustion engine just right after the exhaust manifold. Comprising of two honeycomb-shaped ceramic blocks housed in the main body one ahead and the second one towards the exit. The first ceramic block mainly consists of platinum and rhodium metals.
The second block consists of platinum and palladium metals. An oxygen sensor (bank 1) is placed just before the catalytic converter so that it can read the amount of oxygen (unburned fuel) in the system and give the feedback to the engine’s computer for precise calculations and adjustments for any needed corrections for a smooth running of an engine.
The second oxygen sensor (bank 2) may be fitted after the catalytic to monitor the health of the catalytic converter. Bank 2 oxygen sensor will trigger the check engine light whenever the catalytic converter is out of the thresholds, this does not mean that the catalytic converter should be removed or replaced.
Although catalytic converters are most commonly applied to exhaust systems in automobiles, they are also used on electrical generators, wood stoves, forklifts, mining equipment, trucks, buses, locomotives, motorcycles, and on ships. They are even used on lean-burn engines as well as kerosene heaters and wood stoves to control emissions.
How the catalytic converter works
Whenever an engine is running the byproduct of combustion is the exhaust gasses, these exhausts comprise of;
- Carbon monoxide
- Nitrogen oxides
All these above gasses are dangerous to the ozone and the human in general. As the gasses go through the first block of platinum and rhodium, the metals in the first block react with nitrogen oxides to reform into nitrogen and oxygen gases (harmless). Then the rest of the gasses move into the second block. Here carbon monoxide reacts with oxygen to form carbon dioxide. The unburned hydrocarbons also reacts with oxygen to form water and carbon dioxide.
This is why water is usually seen running out of the exhaust in the morning and evaporates once the exhaust pipe gets hot. So before and after the catalytic converter the gasses will change from red to blue as follows; carbon monoxide > changes to carbon dioxide and nitrogen oxide > changes to nitrogen and oxygen hydrocarbons > changes to water and carbon dioxide. This means the presence of the ceramic blocks, all the red harmful glasses have been reduced to more friendly gasses.
Why the catalytic converter is the most sourced by vendors in the black market?
Due to the existence of precious metal inside the first block and second block, the black market is ready to do anything to get your catalytic converter out of your car whether it’s still working or not… these would be illegally sold overseas for crushing and extracting the precious metals for recycling. One kilo of the honeycomb pellets would cost more than $500 in the black market.
Car owners would be convinced by technicians to remove the catalytic converters for them to milk cash out of it from the black market especially if the check engine comes on with the trouble code P0420. This could be a faulty oxygen sensor or just a clogged catalytic that can be cleaned and you are good to go. Due to the high costs of manufacturing, it has proven to be difficult to get catalytic converters being sold locally in most countries.
Because of the external location and the use of valuable precious metals including platinum, palladium and rhodium, catalytic converters are a target for thieves. The problem is especially common among late-model trucks and SUVs, because of their high ground clearance and easily removed bolt-on catalytic converters.
Welded-on converters are also at risk of theft, as they can be easily cut off. Pipe cutters are often used to quietly remove the converter but other tools such as a portable reciprocating saw can often damage other components of the car, such as the alternator, wiring or fuel lines, thus, there are dangerous consequences.
Causes of catalytic converter clogging and how to avoid them
There are various causes of catalytic converter clogging but we shall only talk of the most common ones.
- Always replace your service parts timely and only with genuine parts and on. Dirty filters (fuel filter, air filter, and oil filter) means your engine is struggling to breathe hence too much incomplete combustion, this would translate into overworking the catalytic converter to clean the mess hence getting it to clog soonest.
- Avoid sudden engine revs. Your engine is either running rich or lean but the car computer will always adjust the parameters by itself to get the engine a happy running point. When you suddenly hit the revs high or drop them instantly there is a delay on the car’s computer calculating and adjusting the parameters to optimum. In this delay period there is too much production of harmful gasses that will eventually soak up the catalytic converter with impurities. Always get gentle on the throttle unless it is an emergency.
- Avoid holding up the engine on very high revs for longer periods for this will get the converter to glow. This will make the chemical composition of the reacting materials to be thrown out of proportion hence weakening their ability to work perfectly.
Can a clogged catalytic converter be repaired?
The catalytic converter works within certain limits. Lower limits of the threshold being catalytic have just started to clog and the higher limits being it is fully clogged. This means that the catalytic does not just clog once and get to the higher limits. In the very first stages of code P0420a catalytic converter can be removed soaked in detergent for overnight, rinsed and fitted back to the car. If it wasn’t on the higher limit threshold it should work perfectly. The results will be okay especially if the honeycomb is not broken.