The man has also previously appeared in similar cases.
At four o'clock last night, a patrol decided to carry out a routine driver and vehicle inspection on county road 127 in Sävsjö.
When the man could not explain how he got the eight catalysts, which the police found in his luggage, he was arrested.
He is now suspected of theft or alternatively receiving.
A woman of the same age was also in the car and they were both arrested on Friday morning.
- The man has been suspected of catalyst theft before. He and the woman will be questioned during the day, says Johnny Gustavsson, press spokesperson at the Police.