The Walkinshaw Andretti United Mustang driver was running second to eventual winner Cam Waters in the early stages when the electronic gremlin struck.
It took out the car’s shift cut – which allows full-throttle upshifts – and wreaked havoc with his pit lane speed limiter, resulting in a lowly 10th place finish.
“I’m not sure exactly what lap but it was really early, before lap 10,” Mostert told Speedcafe of when the problem first reared its head.
“I had to learn how to shift old-school like a Formula Ford, trying to work out which gear would shift with a blip, and which shift you’d have to clutch on the upshift.
“The downshifts were fine, but I was snagging a lot of limiter in places and just losing a lot of straight line speed as well.”
Mostert’s issue was obvious on the TV broadcast as onboard footage showed the gear position indicator on his dashboard changing erratically, often showing R for reverse after he upshifted.
Although Mostert said that in itself was not a distraction, the time lost in pitlane was disastrous.
Having dropped from second to fourth in the first round of stops, Mostert battled his way back through to second before being dumped outside the top 10 with his second pit visit.
DRAMA FOR MOSTERT IN THE PITS 😱
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“We got away with it in the first stop, but I did definitely have a slow entry, it got stuck with the wrong gear position [being read by the sensor] and the limiter wouldn’t work,” he said.
“Then in the last one it did the same thing but the whole time, it thought I was in fourth gear and the limiter wouldn’t work for whatever reason.
“I was in first, but it was thinking I was in fourth. It would cut the engine really aggressively, I was stuck at 20 kay an hour, 18 kay an hour, with the engine not running really on the speed limiter.
“I lost a lot of time today, still got some points, but I feel like we deserved a surfboard, we had a really fast car considering we had a problem for most of the race.”
Mostert took 10th from Anton De Pasquale in the closing stages with a divebomb at Turn 11 that included contact between the WAU entry’s right-front and the Shell car’s left-rear.
“I had a dip. I felt like I was completely under control but he just kind of squeezed me a little bit and I couldn’t go any narrower or it’d put us both in,” explained Mostert.
“I think it just clipped his rear wheel on my front wheel. I was trying to come back from a long way because I just couldn’t live with anyone in a straight line.
“I had a crack and didn’t want to make contact, but we both got away with it and came out the other side.”
Mostert retains third in the standings but now sits 243 points behind leader Will Brown, who finished seventh in today’s race.