Jeep issued an emissions recall in late 2006 to update the powertrain control module (PCM) software on certain 1997 - 1998 vehicles. As part of the recall, the catalytic converter will also be inspected for damage and replaced as necessary. To see if your vehicle is included in the recall you can visit the Jeep website (owners' section) that allows owners to input their VIN number and check the recalls on their vehicle.
Emissions Recall to Update PCM Software and Inspect the Catalytic Converter on Jeep Wrangler
Average mileage: 100,000 (100,000–100,000)
Exhaust & Emissions affected: 2.5L 4 Cylinder
3 people reported this problem
1998 Jeep Wrangler 100,000 mi, Visitor
when jeep at operating temp valve clatter from converter restriction