DTC P1197: 1/2 O2 Sensor Slow During Catalyst Monitor: Description

The 1/2 HO2S catalyst monitor is performed when engine is running, engine coolant temperature is more than 170°F (76.7°C), throttle is open, vehicle speed is steadily increased to more than 18 MPH and less than 55 MPH, and a light engine load exists for at least 5 minutes. DTC P1197 may be stored in Powertrain Control Module (PCM) if HO2S signal voltage is switching from less than .39 volt to more than .60 volt and back, fewer times than required amount. Possible causes are:

• 1/2 HO2S Ground Circuit Voltage Drop
• 1/2 HO2S Signal Circuit Voltage Drop
• Exhaust Leak
• Excessive Engine Blow By
• 1/2 HO2S Heater Feed Circuit Open
• 1/2 HO2S Heater Ground Circuit Open
• Wiring Harness Intermittent Condition
• Faulty 1/2 HO2S