Is your car engine rattling? Someone might have stolen the catalytic converter

One morning in January this year, when Sohel (pseudonym), a Narayanganj-based businessman, turned the ignition on his Toyota Premio, he heard an unusual rattling noise coming from underneath the car.  

The problem seemed strange to him because only the day before the car was driven back home from an automobile repair shop.

The gas tank was not sufficiently full so he tried to run the car on octane and that is when the noise began. (When the car runs on diesel or octane instead of let's say Compressed Natural Gas (CNG), it's easier for the catalytic converter to function even with missing parts – and doesn't make that rattling noise). 

Sohel ignored it as he had to rush to the office. The next day, the car suddenly stopped running and restarted. But this problem kept recurring.

Seeing no other way, he took the car back to the workshop.   

The chief technician called Ali checked the vehicle and replaced some supporting parts of the engine. The repair seemed to work and Sohel no longer had trouble running the car even on gas. 

However, Sohel got to know the reason behind the rattle. The cause of it originated, he learned when his car was undergoing repair at a different automotive workshop. 

The technicians at the workshop where Sohel took his car back, spotted a polished but still recognisable long welding mark over the steel body of the car's catalytic converter. They told Sohel that his car's silencer piper mati (catalytic converter's ceramic honeycomb filters) were stolen. 

"Initially, I was confused. Why does anyone steal the catalytic converter? What are the materials of a ceramic honeycomb filter? I searched for clues on Google and found that these particular car parts are made of very precious metals," said Sohel. 

Before that day, he spent around Tk40,000 replacing car parts without really understanding the real problem. His car got repaired in at least three workshops. No technician, though, admitted the stealing. 

Sohel had to spend a similar amount of money to get a new catalytic converter. "The spare part was not even available in Dhaka. Later, I bought a used catalytic converter from a Chattogram-based spare parts market," Sohel said. 

Stealing catalytic converters has become a severe concern for car owners, particularly those who own new cars. The price of stolen and moderately new catalytic converters in the black market is comparatively higher than used ones.  

The matter does not get much attention from law enforcement agencies due to the minimal number of complaints. The car owners can neither detect the real issue with their car in the beginning nor can they identify the actual thieves. 

Stealing unique car parts first caught the attention of news media in 2021. In March of that year, two people, including one Sylhet-based workshop owner, were caught by some car owners and handed over to the police. 

Next month, Chattogram Metropolitan Police arrested two others allegedly for stealing catalytic converters. Although there were no media reports on the crime, the stealing of catalytic converters has not stopped. 

What is a catalytic converter?

It is safe to say that owners are usually not aware of catalytic converters before their car begins to make a strange noise and fumes come out of it. And something seems to be missing from the exhaust system. 

A catalytic converter is a small, inflated metal tube underneath a car that filters out the pollutants in the exhaust gas produced by the engine.   

Basically, it is a ceramic honeycomb filter covered by a heat shield and a strong steel body. The honeycomb filter is composed of precious metals including palladium, platinum and rhodium.

Every time a driver starts the engine, thousands of small combustions in each of the engine's cylinder provides energy to move. At the same time, the combustions create fumes that require an exit way.  The catalytic converters receive the fumes and transform them into gases like nitrogen, carbon dioxide, oxygen and water. 

Profess Dr Md Ehsan, a faculty at the mechanical engineering department at Bangladesh University of Engineering and Technology, said that a catalytic converter is a post-engine emission control device having two types of catalysts: reduction and oxidation. 

"Without the reduction catalysts, driving a car will not face big problems. Only the fumes will pollute the air. But, if the oxidation catalysts are removed or stolen, the driver can sense a problematic exhaust system," he said. 

Why steal catalytic converters?

Almost all the spare parts traders and automotive technicians in Bangladesh are aware of catalytic converter thefts. But they seldom entertain journalistic inquiries. 

Only one Chattogram-based car parts importer Tanvir proved exceptional. Over the phone, he provided some insights. 

Bangladesh imports reconditioned cars mainly from Japan and spare parts from Dubai. Dubai also imports reconditioned and used cars from Japan and other European countries. But the cars are cut into pieces and spare parts are extracted. Then the spare parts are exported to other countries like Bangladesh. 

"Usually, Dubai doesn't export catalytic converters because the precious metals it contains have a higher value in the black market. For example, if I want to import a fresh catalytic converter, I have to pay Tk70,000 minimum for it," said Tanvir, hinting about the price at the black market. 

On the other hand, the price of a stolen catalytic converter in Bangladesh ranges between Tk15,000 and Tk40,000, depending on the quality of the product. The more a converter reduces polluted gases, the more it loses its sellable value. 

"Despite the thefts of catalytic converters continuing in Bangladesh, their availability is low because some unscrupulous businesses export the stolen parts," Tanvir said. 

The export destination is vast, starting from India to Dubai, according to some spare parts traders who requested anonymity.

Can the mati get replaced once stolen from the catalytic converters? It can be, but the availability of this is extremely limited and then there's a high price tag attached to it. According to some US and European websites, the rare metal rhodium is sold for around $5,000 an ounce while palladium and platinum are worth $1,000 or more per ounce in the international market. 

The price tags can help us understand why catalytic converters are expensive. On average, a catalytic converter carries about 1 to 2 grams of rhodium, 3 to 7 grams of platinum and 2 to 7 grams of palladium.

Many car owners like Sohel are unaware of the smuggling racket of stolen catalytic converters. Other than keeping a close watch over car technicians during repairs, there is not much one can do.