The #17 Shell V-Power Mustang finished fifth in the 120km race after an off-track excursion at Turn 3 filled the air intake with dirt.
Kostecki had been chasing third-placed Ryan Wood when both sailed off at the tricky corner just over 10 laps from home.
According to DJR, coolant and oil temperature inside the engine reached 123 and 149 degrees respectively.
The engine’s ECU responded to the high temperatures by richening the fuel mixture, allowing temps to normalise over the final laps.
DJR will return the engine to control Ford supplier Triple Eight following the weekend.
Championship leader Kostecki said it was a tough race from the early stages.
“I couldn’t even see where I was going,” said Kostecki.
“The windscreen got really dirty, like lap five or six. It was sort of hard to see and there were a lot of marbles off line.
“So it was quite hard to place the Shell V-Power Ford Mustang, that was a horrible race for us. We’ll take fifth.”
Kostecki won the day’s earlier soft tyre race from pole, but qualified just seventh for the super soft tyre affair.
“We just have to be a bit faster,” he added.
“We struggled a lot at the start of the race, but I felt like after the pit stop, I started coming back towards the front towards Broc (Feeney) and (Ryan) Woody, but ultimately, we just weren’t fast enough.
“We just need to do a bit of homework and try to be better tomorrow.”
Kostecki’s teammate rookie Rylan Gray meanwhile enjoyed his first top 10 finishes of the season in Races 2 and 3 of the Christchurch weekend.
Gray took the flag 11th in Race 2 before being elevated to 10th due to a Zach Bates penalty, before again taking 10th in Race 3.
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