SPARX Group to establish Mirai Creation Fund II; Toyota and Sumitomo investing
ULEMCo delivers first hydrogen dual-fuel van to Ocado

CARB investigation leads to nationwide recall of 500,000+ Cummins heavy-duty trucks due to defective SCR catalysts

The California Air Resources Board (CARB) announced that 500,000 heavy-duty trucks manufactured by Cummins Inc. will be recalled due to excess emissions caused by defective catalysts. The cause of the excess emissions was purely mechanical—the faster-than-expected degradation of the catalyst—and not the product of a defeat device. The degrading catalysts do not pose a safety issue, and do not affect current model year Cummins engine families.

Cummins worked collaboratively with CARB on the voluntary recall which constitutes the largest such effort for heavy-duty trucks to date.

The excess emissions were discovered after CARB launched its new Heavy Duty In-Use Compliance program in 2016. The Cummins action marks the first major recall resulting from the program, in which subject vehicles are equipped with Portable Emissions Measurement Systems (PEMS) to measure truck emissions while operating on streets and highways under typical operating demands and conditions.

As CARB has done with light-duty vehicles (cars and pickups) for decades, it initiated a program in 2016 to bring private fleet-owned or rental trucks that had been operating for several years for testing. Initial readings of some of the Cummins engines revealed higher than expected emissions of NOx. This led to more comprehensive testing by CARB.

The testing confirmed that the selective catalytic reduction (SCR) systems were defective, causing emissions of NOx to exceed state and Federal standards. The same problem was found to affect about 60 engine families under the Cummins name found in a wide range of vehicles, from big-rigs, to larger pickup trucks and some buses.

An engine family is the basic unit that CARB and US EPA use to identify a group of vehicles or engines for certification and compliance purposes.

After CARB shared the initial findings with Cummins, the company conducted its own testing to confirm the failures and agreed to institute a voluntary recall, ultimately affecting more than 800,000 vehicles, to replace the catalysts.

This number includes about 232,000 Dodge Ram 2500 and 3500 vehicles with Cummins engines that had the same SCR defect. Recalls for those vehicles were approved in July 2016 and July 2017, respectively, and are already underway.

The trucks will be recalled in a two-phase operation. Starting in August 2018, owners of the 500,000-plus affected vehicles will receive letters with instructions on how to get their catalysts replaced or receive reimbursement for the cost of the replacement. The second phase begins in March 2019. Replacing the catalyst is required for vehicle owners to renew their California DMV registration on most engine families.

CARB’s in-use testing of the vehicles played a key role in identifying the problem. Once Cummins was made aware of the issue, they cooperated with CARB and US EPA and agreed to recall the full range of engine families, pay for all required repairs and reimburse owners who may have already paid for an SCR replacement.

Following the recall, CARB and EPA will work together to ensure that the affected vehicles will meet all emissions standards.


Do any other states join CA in banning renewals for excessively polluting vehicles? This should be a nationwide law.


We may be at the point where diesel engine manufacturers can no longer meet emissions and ever increasing efficiency requirements using diesel technology. Hybrids using gasoline and electricity may be the better choice.


It does indeed appear that we have at last come to the realization that a Diesel engine can never be made clean enough, certainly not for a vehicle that will be allowed in urban areas.


Gasoline technology may have generally lower NOx emissions, but that's offset by generally higher VOC, CO, and PM emissions. Not a good trade-off for urban air quality concerns in my opinion.

Diesel technology is well on its way of solving the NOx emissions issue anyway.

The comments to this entry are closed.