Download IF YOU CONFIRM A rattle or buzz noise during acceleration OR A MIL ‘ON’ with DTC P1273 A/F Sensor ACTION • Inspect for a loose heat shield at the bottom of the Bank -1 catalyst. It may have “separated”. • If heat shield is loose replace the catalyst. SERVICE PROCEDURE 1. Put the vehicle on a hoist. 2. Inspect the Bank-1 catalyst heat shield for looseness by attempting to move heat shield by hand see Figure 2. 3. Inspect the Bank-1 heat shield welds for separation see Figure 3. 4. If the heat shield is loose so it can be moved by hand or any of the 3 heat shield welds are separated, replace the catalyst. 5. If the incident included DTC P1273, after replacing the catalyst, you must also complete the following steps: 1. Erase the DTC. 2. Clear self learning using CONSULT WORK SUPPORT mode. Select SELF LEARNING CONT then START followed by CLEAR.