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DTC P1195: 1/1 O2 Sensor Slow During Catalyst Monitor

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article.
NOTE: The 1/1 oxygen sensor may also be referred to as upstream oxygen sensor. 1/1 oxygen sensor catalyst monitor is monitored 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 light engine load exists for at least 5 minutes. DTC may be stored in Powertrain Control Module (PCM) if 1/1 oxygen sensor signal voltage is switching from less than .39 volt to more than .60 volt fewer times than required. Possible causes are: exhaust leak, coolant or excessive oil entering combustion chambers, defective 1/1 oxygen sensor, or defective connectors or wiring.
  1. Turn ignition on with engine off. Using scan tool, check for DTCs. If DTC SPECIFIC GOOD TRIP counter is displayed and equal to zero, go to next step. If DTC SPECIFIC GOOD TRIP counter is not displayed and equal to zero, go to step  9.
  2. Ensure ignition is on with engine off. Using scan tool, actuate oxygen sensor heater test and then use scan tool to monitor 1/1 oxygen sensor voltage for 2-3 minutes. Oxygen sensor heater test may also be referred to as O2 heater test. If 1/1 oxygen sensor voltage becomes less than 1.5 volts within 2-3 minutes, go to next step. If 1/1 oxygen sensor voltage does not become less than 1.5 volts within 2-3 minutes, go to step  7.
  3. Start engine and warm engine to normal operating temperature. Check exhaust for excessive smoke caused by coolant entering combustion chambers or high oil consumption. If excessive smoke caused by coolant entering combustion chambers or high oil consumption does not exist, go to next step. If excessive smoke caused by coolant entering combustion chambers or high oil consumption exists, repair engine as necessary. Perform TEST VER-5 .
  4. Check for exhaust leaks between engine and 1/1 oxygen sensor. The 1/1 oxygen sensor is located on exhaust pipe in front of catalytic converter. If no exhaust leaks exist, go to next step. If exhaust leaks exist, repair exhaust system as necessary. Perform TEST VER-5 .
  5. Shut engine off. Using voltmeter, backprobe terminal No. 3 (Black/Light Blue wire) on 1/1 oxygen sensor connector and terminal A4 (Black/Light Blue wire) on PCM connector C1. PCM is located on firewall, near brake booster. This is the ground circuit for 1/1 oxygen sensor. Start engine and allow engine to idle. Warm engine to normal operating temperature and note voltage reading with engine idling. If voltage is less than .1 volt, go to next step. If voltage is .1 volt or more, repair high resistance on Black/Light Blue wire between 1/1 oxygen sensor and PCM. Perform TEST VER-5 .
  6. Shut engine off. Using voltmeter, backprobe terminal No. 4 (Tan/White wire on CNG models or Black/Dark Green wire on gasoline models) on 1/1 oxygen sensor connector and terminal A24 (Tan/White wire on CNG models or Black/Dark Green wire on gasoline models) on PCM connector C1. This is the signal circuit for 1/1 oxygen sensor. Start engine and allow engine to idle. Warm engine to normal operating temperature and note voltage reading with engine idling. If voltage is less than .1 volt, replace 1/1 oxygen sensor. Perform TEST VER-5 . If voltage is .1 volt or more, repair high resistance on Tan/White wire (CNG models) or Black/Dark Green wire (gasoline models) between 1/1 oxygen sensor and PCM. Perform TEST VER-5 .
  7. Turn ignition off. Disconnect 1/1 oxygen sensor connector. The 1/1 oxygen sensor is located on exhaust pipe in front of catalytic converter. Turn ignition on with engine off. Using scan tool, actuate oxygen sensor heater test. Oxygen sensor heater test may also be referred to as O2 heater test. Using voltmeter, check voltage at terminal No. 1 (Dark Green wire on CNG models or Violet/Orange wire on gasoline models) on 1/1 oxygen sensor connector. If voltage is more than 11 volts, go to next step. If voltage is 11 volts or less, repair open on Dark Green wire (CNG models) or Violet/Orange wire (gasoline models) between 1/1 oxygen sensor and fuse No. 19/20 (10-amp for CNG models or 15-amp for gasoline models). Fuse No. 19/20 receives voltage from Auto Shutdown (ASD) relay. Fuse No. 19/20 and ASD relay are located in power distribution center at driver's side of engine compartment, near battery. Perform TEST VER-5 .
  8. Stop actuation of oxygen sensor heater test. Turn ignition off. Ensure 1/1 oxygen sensor connector is still disconnected. Using ohmmeter, check resistance between ground and terminal No. 2 (Black wire) on 1/1 oxygen sensor connector. If resistance is less than 5 ohms, replace 1/1 oxygen sensor. Perform TEST VER-5 . If resistance is 5 ohms or more, repair open on Black wire between 1/1 oxygen sensor and ground connection. Ground connection is located at firewall end of driver's side cylinder head. Perform TEST VER-5 .
  9. Start engine and warm engine to normal operating temperature. Check exhaust for excessive smoke caused by coolant entering combustion chambers or high oil consumption. If excessive smoke caused by coolant entering combustion chambers or high oil consumption does not exist, go to next step. If excessive smoke caused by coolant entering combustion chambers or high oil consumption exists, repair engine as necessary. Perform TEST VER-5 .
  10. Check for exhaust leaks between engine and 1/1 oxygen sensor. The 1/1 oxygen sensor is located on exhaust pipe in front of catalytic converter. If no exhaust leaks exist, go to next step. If exhaust leaks exist, repair exhaust system as necessary. Perform TEST VER-5 .
  11. Shut engine off. Inspect wiring harness and connectors between 1/1 oxygen sensor and PCM. PCM is located on firewall, near brake booster. Inspect PCM connectors and 1/1 oxygen sensor connector for corroded, pushed out or damaged terminals. Also, check for related Technical Service Bulletins (TSBs). If no problems exist, test is complete. If any problems exist, repair wiring or connectors as necessary. Perform TEST VER-2 .
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