Vettel finished in fourth place in his Red Bull RB9.
"It’s very important for us to put good mileage on the car and this morning that wasn’t really possible," said the reigning world champion.
"We had a small software issue this morning, I think many teams had. That wasn’t ideal but we got it fixed and after that it was another decent day."
Vettel admits it was difficult to preserve the tyres.
"It is good to back in Barcelona. It is a good circuit to judge a car on and a good indicator of where you are but we need to be careful of doing that as it’s pretty cold at the moment and it’s quite tough to keep the tyres alive for many laps. So hard to know. But overall, not a bad day again."