Nick Heidfeld sat out the afternoon test session at Barcelona on Tuesday with a lingering cold.
A few days earlier, the German revealed his illness but said he was nonetheless scheduled to drive on the first and last days of the final pre-season test this week.
Actually, the R31's settings had to be switched over to teammate Vitaly Petrov at the lunchbreak.
Germany's Auto Motor und Sport reports that Heidfeld has now been sick for a week.
"I thought I would be over it by now, but the cold will not go away," confirmed the 33-year-old. "I didn't feel good in the car in the morning (on Tuesday)."
The report said Renault is now scheduling to have Heidfeld back to the car on Thursday afternoon, before he drives all day on Friday.
"When I sit back in the car, the new package will be complete," he said. "What I have tried already, felt alright."