Lewis Hamilton's was forced to call an early halt to his morning session at Jerez on Wednesday.
Hamilton had completed just seven laps when he returned to the pits with flames coming out of the back of his MP4-24.
McLaren's mechanics were quick to remove the engine, but Hamilton played down the incident.
"We had an issue, but I think they're fixing it and we'll be back out as soon as possible," he told reporters.
"But the car was good this morning. I didn't get many laps, but I'm looking forward to getting back out."
Toyota have so far dominated proceedings in the south of Spain, and Hamilton admits quite a few teams have impressed in pre-season testing.
"This is my first day with Ferrari being at the same track, so for me it looks very similar to every other year - 2007 and 2008," Hamilton said.
"Everyone's times are looking good, some consistently, some not. But I haven't done many laps today so I can't say.
"Just from looking at the times, it looks like (Toyota) are doing quite a good job. But I think a lot of the teams are doing quite good jobs. The Renault doesn't look bad, the BMW doesn't look bad, so there are quite a lot of teams looking pretty impressive at the moment."
Source : Planet F1