Step 1: Mohan is left of Pawan, and Sohan is right of Pawan, so Pawan sits between Mohan and Sohan.
Step 2: Rohan is between Sohan and Pawan, so Rohan sits immediately after Pawan and before Sohan.
Step 3: This fixes the full order left to right as Mohan, Pawan, Rohan, Sohan.
Step 4: The second position from the left is Pawan, whose code is 2. \[ \boxed{2} \]