The crew decided not try and fix the problem and risk further damage and retired from the event. By that stage, so much time had already been lost that even if the turbo had been fixed, Cox would have been unable to gain any championship points.
It is the second rally in a row that turbo problems have proved costly, with Cox only managing three points at the last round in Whangarei to add to the 19 he scored in the opening round in Otago.
"We don't think this is the same problem, although we haven't quite worked out what it is. We've got to pull it apart and see what happened and why it happened."
It was only the second time 25-year-old Cox has competed in Canterbury, and last year be won three stages. The speed he showed in 2016 saw him hoping for a good result this time.
"Going all that way down to the South Island for two stages was very frustrating. We were looking for good [championship] points and so to come away with nothing is a hard one."
The national series is now at the halfway point, with the next round the Gold Rush Rally of Coromandel on August 26.
Cox admits the chance of repeating his second place of last year's national championship, or better, have realistically gone.
"It's probably too hard to come back now because half the points have gone already. But we are still looking for good results, good speed, podiums - we haven't won a rally yet - so there are other goals.
"The car is capable of it, except for the mechanicals, so we will look for a better second half.
"After last year when we had such a good year and then we had done work on the car to make it better ... we've never had a year so bad before."
With more than two months before the next rally, there is time to take the car apart and do some outside competition testing.
"We do a lot of testing ourselves to try and find [faults] on test days rather than on an event but they are happening on events. That's probably because on a rally there's a bit more endurance and you drive the car a little bit harder and take more of a risks."
