It started with smoke coming from the engine or an alert sign going off to advise the driver to add more coolant, according to owners of BMW vehicles that caught fire in motion in recent weeks.

Sharing their experiences of watching their BMW vehicles burning on the road, some said via online communities that they at least had time to escape from the vehicles as it was not like the engine exploded.

Since December 2017, a total of 30 BMW vehicles have caught fire on motorways here. Of the number, 19 were the diesel version of the BMW 520, all manufactured before 2017. 

Questions have since been raised over why the series of incidents involving the German luxury cars catching fire has happened only in South Korea, though the vehicles are sold in more than 140 countries.

BMW Korea has explained that it believes the cause of the problem was a flaw found in the exhaust gas recirculation module, without elaborating further.

Some auto experts here partly agree with BMW’s rationale, saying it is highly likely that the plastic part, where “very hot” gas passes through, must have melted.

EGR coolers are devices designed to reduce nitrogen oxide emissions for internal combustion engines.

If an EGR cooler malfunctions, it could result in plastic parts of the module, such as valves and surge tanks, melting. Hypothetically, gases, coolants or particles could have leaked from the EGR module, increasing the risk of fire from the overheated engine, said Lee Ho-geun, an automobile engineering professor at Daeduk University.

Park Byung-il, a master automotive technician, also suggested that the incidents could be related to the nation’s strict emission rules.

The size of an EGR part that takes in nitrogen gases is a bit bigger than those installed in other diesel vehicles abroad to comply with the Korean environment law, he told Yonhap News Agency. More hot gases funneling through the pipe could have caused the EGR devise to overload, making it more prone to fire, he added.

An industry insider, however, refuted claims that attribute the cause of the incidents to the sweltering heat sweeping across the country.

“The EGR devices are engineered to resist high temperatures, even around 400 degrees Celsius, to handle hot gases injected from the engine. If the hot weather is the cause of (BMW) incidents in Korea, how could other vehicles operate in hot countries in the Middle East,” said a technician at a foreign carmaker in Seoul on condition of anonymity.

Meanwhile, another BMW vehicle, a 420d, caught fire on an expressway connecting Seoul and Incheon on Tuesday afternoon, according to local reports.

The BMW 420d is on the list of the company’s voluntary recall program.

By Cho Chung-un (christory@heraldcorp.com)