HO2S Heater Monitor
WARNING: This page does not describe the selected car, but rather 164 other vehicles, including the 2002 Volvo V70, 2002 Volvo V40, 2002 Volvo S80, 2002 Volvo S60, and 2002 Volvo S40. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
When negative battery cable is disconnected, all readiness test codes are cleared.
Connect scan tool to DLC. Start engine, and let idle for 10 minutes. Check for readiness code with scan tool.