Rickard Rydell has not yet recovered from his illness, thyroiditis, and neither he nor the team will be at the World Touring Car Championship races at the Hungaroring this weekend.
"This is a difficult situation for all of us, and it's a real shame to miss out on so much valuable running in this opening part of the season," said Rydell.
The former BTCC champion missed the previous WTCC race in Morocco as well due to the illness.
"We were already running behind in terms of testing and would have really needed these races, but all I can do is follow the doctors' advice and be patient. I'm making progress, but stepping into a racing car at this moment in time is just out of the question.
It's one of the most frustrating things I've experienced, and I really hope to be back on form for the Nurburgring. I can't wait to get back in the car," said Rydell.
No replacement driver
The team considered bringing in a replacement driver but chose not to in the end and is instead aiming to be back for the WTCC race at the Nurburgring Nordschleife.
"We are facing a challenging start to this season – it's most unfortunate. The main priority is Rickard's health and we have the utmost respect for the doctors' recommendations.
"The last thing we would do is subject Rickard or anyone else in the team to any unnecessary risks, and we're prepared to give this the time it takes," said team manager Nicklas Karlsson.
"On the sporting side, this is obviously far from ideal – particularly at a time when we were supposed to get our real testing programme underway following the first flyaway races.
"We have carefully considered our options for this weekend together with our partners and have come to the conclusion not to bring in a replacement driver. Instead, our sole focus for now is to make sure we put all the arrangements in place for a competitive return at the earliest possible opportunity."