Right from the start, Karthikeyan was warned on the Team Radio to "cool off, cool off".
His team-mate Pedro de la Rosa had to retire after the brakes of his car failed.
"I had to slow down because we had the brake issues. This is the maximum we could have got out of this race and I am happy to finish the race," Karthikeyan told PTI.
"I had to slow down, cut the pace otherwise I could have also ended up like Pedro. To finish the race was important and I got to it," he said.
Asked if the problem did not surface during the qualifying or practice, Karthikeyan said, "It was only on the straight runs."
Asked if his team used the new updates in the car, he said they were not that keen to do it in this race.
"There was a reliability issue. We did not want to risk it using in this race."
Pedro de la Rosa, said, "It was a shame that I had to retire because the car was running good on hard tyres. With no warning, brakes failed. But the important things is the car is not damaged for Abu Dhabi. We have to fix it since Abu Dhabi is also very demanding circuit for the brakes."