The issue reared its head during the squad's final pre-event test earlier this week, and with no fix being possible as yet, left them with no option but to withdraw on safety grounds.
“We're a bit shattered. The car would ‘chuck a code' into the system every now and then which would put the car in limp mode,” Miedecke explained.
“It wasn't an issue that you could just fix by stopping the car on track and restarting things, it needed to be brought back to base.
“It's a safety issue. It's fine testing at Winton but if it happened coming out of McPhillamy Park, for example, at 200km/h then there's a good chance we get drilled by another car which is not safe for us and for other competitors around us.
“To have something like this throw itself at us so close to the event is frustrating because everything else had been sorted.”
The blow comes after an extensive testing programme.
“The gearbox was a big tick, the engine? Tick. The safety? Tick. Handling? Tick. Everything was looking really good and it was definitely a step forward on the old car,” Miedecke added.
“It was going to be competitive and will be in the future.
“This is just one of those strange, unforeseen issues that crop up when you turn a road car into a race car, with all their modern technology. It's a ghost in the system that we've not been able to find.
“We'll all be watching closely on Stan Sport to see how the race plays out. It's going to be a fantastic battle with lots of good cars, and we wish we could've been safely part of it.”
Ambrose becomes the second Supercars champion to withdraw from the production car enduro during race week, Shane van Gisbergen having been ruled out on Tuesday due to COVID-19.
Practice for the Hi-Tec Oils Bathurst 6 Hour starts tomorrow, with Stan Sport to deliver live and ad-free coverage on Saturday and Sunday.