The Brazilian has been experiencing a challenging start to his sophomore Formula One campaign, with his Swedish team-mate outqualifying him in all three opening races. Ericsson also finished ahead on the two occasions when both cars made it to the end.
“I can confirm I do get a new chassis here," Nasr said in Thursday’s FIA press conference in Sochi.
“I think it's a sensible step from the team, that we're looking further to discover these problems, these handling issues that I'm having.
“Since we put the car on track in Australia we've been having this very strange behaviour, and it's very unpredictable to drive it.”
Pressed to reveal whether Sauber, whose financial situation remains quite precarious, had found out what was wrong with his old chassis, Nasr replied: “Not that they could identify.
“There are so many places to look at, so for this we need the resources, the time.
“The cars hadn't been back at the factory, so it was really good to have a full look to every detail if we could, and I'm sure they're doing all they can with all the things we have in our hands.”
Sauber team principal Monisha Kaltenborn recently admitted that the Swiss outfit’s current struggles have been delaying upgrades to the 2016-spec C35.
Nasr had one of his better race results of 2015 in Sochi, with the 23-year-old claiming P6 around the former Winter Olympic Games venue.