Sebastian Vettel and Mark Webber were quiet when asked about Red Bull's only apparent achilles heel.
The otherwise-dominant team did not use the energy recovery technology at all in Melbourne, while in Malaysia Webber encountered two failures while Vettel won in Sepang despite turning off his KERS as a precaution.
"For safety reasons we did not run it for part of the race on Sebastian's car," confirmed team consultant Helmut Marko to F1's official website.
Earlier, Vettel had to fiddle regularly with the brake balance aboard his RB7 as KERS was turned on and off, as the system stores energy under braking.
It was a bit annoying because I was constantly pressing buttons
"It was a bit annoying because I was constantly pressing buttons," the German told Auto Motor und Sport.
What exactly was wrong, he was not saying. "I'm not allowed to," said Vettel.
Australian Webber, who had a tough run to fourth on Sunday after a KERS failure on the formation lap, added: "Sorry, you'll have to ask the engineers."