"During FP1, we noticed an anomaly in the PU data from Kvyat's car," tweeted Honda. "With only a short time to investigate the matter fully between FP1 and FP2, we have therefore decided to change the PU on his car as a precautionary measure."
Ironically, at the same time as the power unit was being changed, speaking at the FIA press conference, Honda F1's technical director, Toyoharu Tanabe, was addressing the issue of reliability.
"So far we have started this season with a reasonable performance and reasonable results," he told reporters. "But reasonable means not fantastic yet.
"We see clearly there is still a big gap between the frontrunners and us," he admitted. "So, we really need to push to improve our performance to compete with the others here. We understand it's not easy to improve our performance immediately but we keep pushing."
While there is no penalty following today's change, the move confirms that other than performance the Japanese manufacturer still needs to work on reliability.
While Honda addresses its (unspecified) issues, Renault has issued new-spec MGU-Ks to all its drivers as a result of issues first encountered in Australia by Carlos Sainz and then both works drivers in Bahrain, while Ferrari has supplied new control electronics systems to its three teams.