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DTC P1195: Slow 1/1 O2S During Catalyst Monitor: Testing

NOTE: 1/1 HO2S may also be referred to as an upstream oxygen sensor. On Federal models, 1/1 HO2S is located in exhaust downpipe in front of catalytic converter. On Calif. models, 4.0L 1/1 HO2S is located in front exhaust manifold. On 4.7L, 1/1 HO2S is located in left (driver's side) exhaust downpipe in front of catalytic converter.
  1. Turn ignition on, with engine off. Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIP counter is displayed and displayed count is "0", go to next step. If DTC SPECIFIC GOOD TRIP counter is not displayed or displayed count is not "0", go to step  11 .
  2. Ensure ignition is on. Using scan tool, actuate O2 HEATER TEST. Using scan tool, monitor HO2S voltage. HO2S voltage should be less than 1.5 volts within 2-3 minutes. If voltage is as specified, go to next step. If voltage is not as specified, go to step  8 .
  3. Start engine and allow it to idle. Check exhaust system for leaks between engine and catalytic converter. Repair exhaust system as necessary. If exhaust system is okay, go to next step.
  4. Ensure engine is still idling. Check exhaust system for excessive smoke caused by internal oil or coolant consumption. Repair engine mechanical condition as necessary and replace 1/1 HO2S. If engine mechanical condition is okay, go to next step.
  5. Turn ignition off. Using a voltmeter, backprobe Black/Light Blue wire between 1/1 HO2S connector and terminal No. 4 at PCM C1 connector. See Figure . PCM is located on firewall in right rear corner of engine compartment. Start engine and allow it to reach normal operating temperature. If voltage drop is less than .1 volt, go to next step. If voltage drop is .1 volt or more, repair poor connection causing high resistance on 1/1 HO2S ground circuit (Black/Light Blue wire) between 1/1 HO2S and PCM. See WIRING DIAGRAMS article.
  6. Turn ignition off. Using a voltmeter, backprobe Light Green/Red wire between 1/1 HO2S connector and terminal No. 24 at PCM C1 connector. See Figure . Start engine and allow it to reach normal operating temperature. If voltage drop is less than .1 volt, go to next step. If voltage drop is .1 volt or more, repair poor connection causing high resistance on 1/1 HO2S signal circuit (Light Green/Red wire) between 1/1 HO2S and PCM. See WIRING DIAGRAMS article.
  7. At this time, 1/1 HO2S is assumed to be defective. Replace 1/1 HO2S.
  8. Turn ignition off. Disconnect 1/1 HO2S connector. Turn ignition on. Using scan tool, actuate O2 HEATER TEST. Measure voltage between ground and Orange/Dark Green wire (Federal models) or Violet/White wire (Calif. models) at 1/1 HO2S connector. If voltage is more than 11 volts, go to next step. If voltage is 11 volts or less, repair open in Orange/Dark Green wire or Violet/White wire.
  9. Turn ignition off. Measure resistance between ground and Black wire at 1/1 HO2S connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in 1/1 HO2S heater ground circuit (Black wire).
  10. At this time, 1/1 HO2S is assumed to be defective. Replace 1/1 HO2S.
  11. Start engine and allow it to idle. Check exhaust system for leaks between engine and catalytic converter. Repair exhaust system as necessary. If exhaust system is okay, go to next step.
  12. Ensure engine is still idling. Check exhaust system for excessive smoke caused by internal oil or coolant consumption. Repair engine mechanical condition as necessary and replace 1/1 HO2S. If engine mechanical condition is okay, go to next step.
  13. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, reconnect all connectors. Start engine. Wiggle 1/1 HO2S connector and wiring harness while monitoring scan tool display. If GOOD TRIP counter display count changes to "0", repair connector or wiring harness where wiggling caused display to change. If GOOD TRIP counter display count does not change to "0", no problem is indicated at this time. Check for any related technical service bulletins that may apply.
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