Mostert engineer reveals issue behind 'painful' slump

A suspected gear position sensor issue has put a major dent in Chaz Mostert's title aspirations, with a podium going begging at the Boost Mobile Gold Coast 500.

Mostert started third and loomed as eventual winner Cam Waters' closest rival, only to come home 10th after losing delayed by gear sensor gremlins.

The Walkinshaw Andretti United driver fought through the issue to reel off overtakes and regain second position before his second stop, where he bled time and plummeted down the order.

Speaking after the race, Mostert's Race Engineer Sam Scaffidi cut a forlorn figure, with the two-time Bathurst winner now 243 points adrift of championship leader Will Brown with 450 points remaining.

"That was pretty painful," Scaffidi said on the broadcast.

"Not sure we would have got the race win, but definitely one that we could have got P2 for.

"It's just gutting for everyone here, considering how strong the car was in qualifying and how strong the race pace was. It was awesome to see up until that point, and then kind of all just went downhill from there."

Mostert made his second stop on lap 58 of 85, and almost came to a stop as he transited through pit lane. Such was the crawl, that Matt Payne got past in the fast lane.

The WAU star continued to manage the issue and muscled past Anton De Pasquale in the closing laps, but was unable to overhaul Richie Stanaway for ninth.

When asked when the issue first arose, Scaffidi said: "It was pretty early, pretty early into the first stint.

"So for Chaz to drive around that issue, like, it's just credit to him, he did a mega job.

"As far as the issue goes, we think it's the gear position sensor. We've still got a lot of digging into to work out what's going on there. But, yeah, really, really tough."

On track action at the Boost Mobile Gold Coast 500 continues on Sunday with Boost Mobile Qualifying at 10:10am local time/11:10am AEDT. Tickets for the event are on sale now.