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With the 5.6-liter V8 and Cummins 5.0-liter diesel, first introduced in 2015, the Nissan Titan had the two flavors of engines most truck buyers were looking for. Then in 2019, it dropped the diesel. At the time, it seemed odd because the diesel put out more torque and had better performance than any Nissan powerplant. And it was one of the cleaner diesel engines on the market. 

Why is there a class-action lawsuit over the Titan diesel engine?

2021 Nissan Titan
2021 Nissan Titan | Nissan

But now a class-action lawsuit has been filed over the location of the exhaust fluid filler tubes. It says it can cause the accidental dumping of exhaust fluid into the diesel fuel tanks. You can’t mix exhaust fluid with diesel fuel. Doing so can contaminate the fuel, leading to damage throughout the fuel system. This isn’t about any flaws with the engine itself.

And in a separate issue, the lawsuit also alleges exhaust fumes enter Titan cabins, according to Carcomplaints. The lawsuit takes in all years of Cummins 5.0-liter availability from 2016 to 2019 model years. Owners have taken their pickups into dealers but were told there was nothing wrong with their trucks. 

The lawsuit points to a number of technical service bulletins. It says this indicates that Nissan knew about these issues but was unable to resolve them. Nissan became aware of owners accidentally putting exhaust fluid into the filler necks of the fuel tanks. It issued a TSB in 2018.

Titan diesel Technical Service Bulletins allegedly show Nissan knew of these problems

2021 Nissan Titan
2021 Nissan Titan | Nissan

The TSB specifically pointed out “ CAUTION: Putting Diesel Exhaust Fluid into the diesel fuel system will contaminate the entire fuel system causing permanent damage to system components. DEF contamination requires replacement of the complete diesel fuel system.” 

It also listed some of the results of mixing the fluid. They include crank no start, long crank or hard to start, rough idle, low power warning, fuel gauge inoperative or erratic operation, and noise from the stage one fuel pump. It continues, “IMPORTANT: Damage to the diesel fuel system due to DEF contamination is not covered by the Nissan New Vehicle Warranty and will be the responsibility of the vehicle owner. Vehicle owners must be extremely careful to put the appropriate fluid/fuel into the appropriate tank.”

The cost of the repair was $23,648.89

2021 Nissan Titan
2021 Nissan Titan | Nissan

Plaintiff had his Nissan dealer service his Titan when both the diesel fuel and diesel exhaust fluid filters were replaced. The exhaust fluid tank was also filled. A few months later a Water in Fuel” warning light came on. Taking it back to the same dealer, the owner was told that the exhaust fluid had contaminated the fuel system. The repair would cost $23,648.89. 

The lawsuit alleges that the dealer made the mistake of filling the wrong filler tube, putting exhaust fluid into the fuel tank. Though Plaintiff had an extended warranty, Nissan said it would not pay for the repairs. The suit maintains that because of this unfortunate placement of the filler tubes, owners overpaid for their trucks, pay for damaged fuel lines, make repeated dealership visits, and now their trucks have less value. 

This was filed in the US District Court for Middle District of Tennessee, Nashville Division. 


Nissan Drops Titan Diesel and Regular Cab