Repairs to the barriers took some time and the decision was taken not only to abandon the Toyota race but to cancel the following TCM action too.
Despite wins for John Bowe and Bruce Williams on Saturday, Johnson already had an unassailable lead at the top of the standings.
“I'd be lying to say that I didn't come into today feeling pretty nervous,” he said after Saturday's races.
“It's worked out really well and I can't thank TCM, my guys Nick and Robbie and all our sponsors on the car for what they've done this year. It's been a tough year.”