2005 Mercedes-Benz E500 4MATIC Check Engine Light P2096 - Catalyst Fuel Trim Too Lean Bank 1

I own a 2005 Mercedes-Benz E500 4MATIC with 183,000 miles. The check engine light is on with fault code P2096: 'Catalyst Fuel Trim System Too Lean Bank 1'. I recently replaced both oxygen sensors and reset the system, but the check engine light returned. I'm concerned about whether my catalytic converter is faulty without having to replace it yet. How can I diagnose this issue accurately and cost-effectively before purchasing a new catalytic converter? The problem persists even after sensor replacement.