Nissan was forced to call an early end to this week's test at Sebring with its new GT-R LM NISMO World Endurance Championship contender.
The radical LMP1 ran at the Florida circuit on Monday and Tuesday before a component failure resulted in the Japanese manufacturer abandoning a test that could have continued until Friday.
Nissan was piggy-backing onto an Audi test, at which the German marque had one of its heavily-revised 2015 e-tron quattros present, but wasn't committed to running on all five days.
GT-R LM technical director Ben Bowlby told AUTOSPORT: "It was actually a very minor thing, but we just don't have a spare here."
He refused to specify the exact component that had failed, but said it was was "to do with the engine mounting".
Bowlby explained that Nissan had chosen to test at the bumpy Sebring International Raceway to "accelerate the durability cycle".
"We've spent a lot of time at Austin, which is very smooth, so we wanted to come to a particularly harsh environment like Sebring," he continued.
He claimed that the Nissan completed a total of 68 laps over the two days, but wouldn't disclose lap times.
Marc Gene and Olivier Pla undertook all of those laps, while Jann Mardenborough, Harry Tincknell and new signing Max Chilton were present but did not drive.
It remained undecided yesterday whether Nissan will attempt to run the first GT-R LM again ahead of the official WEC test at Paul Ricard on March 27-28, at which it will be present with only one car.
The Sebring test for Nissan followed two runs at Austin totaling nine days either side of Christmas, and a test last month at Palm Beach International Raceway (formerly Moroso), as well as straightline testing at Michelin's US proving ground in North Carolina.
Bowlby confirmed that the GT-R LM was not running its rear hybrid system, which has been conceived only to deploy power harvested from the front axle.
He could not confirm that Nissan had decided against racing this system in the interests of weight saving nor which of the four classes of hybrid power the GT-R LM would run in this season.
LMP1 manufacturers must complete the homologation of their respective challengers next week, and declare the hybrid class in which their design will run for the full season.
Audi is running a solo new-spec R18 at Sebring this week, and concentrating on putting mileage on the car without undertaking a full-blown endurance test.
The Extreme Speed Motorsports squad is also present with both the ARX-4b coupe and the open-top ARX-03b.