The problem, which necessitates a full replacement of the power unit, occurred midway through the morning session in Barcelona after Jenson Button had completed 21 laps and run as high as second quickest in the MP4-30.
“Such issues are all part of testing and we will plan for a productive day of running with Fernando Alonso behind the wheel tomorrow,” tweeted McLaren.
The Woking squad's latest setback comes off the back of a difficult first test in Jerez in which they completed just 79 laps - the fewest of any team.