Heikki Kovalainen has rejoined Caterham as a reserve driver.
The Finn raced for the team between 2010 and 2012, having previously competed for Renault and McLaren.
Kovalainen will take part in first practice sessions in Bahrain and Spain, in order to assist the development of the Caterham CT03.
"It’s obviously great news that I’ll be on track in Bahrain and Spain and I’m really looking forward to getting back to work and helping the team as much as I can," said Kovalainen.
"I’ll be taking part in the two FP1 sessions in Bahrain and Barcelona to give the team my input on the new parts we’re bringing to those races, and I’ll be working closely with the race drivers and the engineers on track and back at Leafield to help everyone get the most out of the new package."
“[Team owner] Tony [Fernandes], [Team principal] Cyril [Abiteboul] and I have been talking about me taking up this role for quite a while, so it’s good to finally be able to announce how I’ll be helping the team in 2013. I’m physically ready to get back into the car and I know my experience can help give the team new ideas and options for directions to take on setup and strategy."
"Having invested in Heikki for our first three years of competition it would be a waste not to leverage the valuable expertise he brings," added Abiteboul. "As F1 is a team sport, he will also provide support to Charles Pic and Giedo van der Garde, who are both doing a good job in their first months with the team."
The restructuring also means that Alexander Rossi will replace Ma Qing Hua in GP2.