Button: We don't know where we are

Jenson Button stayed positive on Monday despite McLaren experiencing a second day of testing woes with their new Honda-powered Formula 1 car in southern Spain, but at the same time admitted that he and the team were unsure where they were in terms of performance.

"We expected this test to be tricky -- and the next two days probably won't be plain sailing, either," the Briton said in a team release.

"But people have short memories. Look at last winter; the first test of 2014 was very tough for everyone too," added the 2009 champion.

"So there are no real worries at the moment. We're just hopeful we've solved our issue. The last run of the day seems to have sorted the problem out, so I hope tomorrow will be a little easier."

After sensor problems limited Spanish team mate Fernando Alonso to just six laps on the first day of pre-season testing at Jerez on Sunday, Button managed only the same amount.

The team, who are starting a new era with their Japanese partners returning to the sport after a six-year absence, had worked overnight to rectify Sunday's problems but a new one emerged once the car was back out on the track.

Button carried out a number of installation laps but the engineers then decided to investigate more deeply and believed they had found the cause. Button did one more trouble-free lap before the day's session ended.

"Today was another tricky day, but we feel like we've overcome the main issue that affected our running during the first two days of the test," said Honda's motorsport head Yasuhisa Arai.

"Despite our lack of mileage, it's been an important learning process for our engineers, who've really started to develop a close working relationship with everybody at McLaren - that's a big positive. For [Tuesday] we're hopeful that we've moved on, and that we can get some more laps completed."

"Hopefully we'll get to the first race and we'll be competitive but we don't know where we stand right now," said Button, the 2009 F1 champion. "In terms of understanding our performance, we're still at zero. We don't know where we are."

McLaren's strong driver line-up promises much - considering Alonso has won two F1 titles - but Button is steering clear of making predictions.

"I haven't even driven the car at full speed so I don't really know. I could pick a number or position out of a hat but it would mean nothing," he said. "We're not going to be setting the world alight with lap times or laps on the circuit."

The problems here on the southern Spanish circuit of Jerez follow on from McLaren's difficulties in testing in the two days following the Abu Dhabi GP in late November.

"Not the easiest start to the season but we know it's a very complicated power unit," Button said. "In terms of the problems we had, we have our head around it and understand the issue."

"I can't tell you that. As I said they're very complicated these days, but it's sorted now," Button said. "We hope for a much more productive day three and day four."

Twelve months ago at the same venue Red Bull also struggled when the new V6 turbo hybrid power unit was introduced but went on to finish second in the Australian opener, before disqualification. They ended the season with three wins.