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Home >> Dodge and Ram >> 2000 >> Ram Van B2500, Van Cargo Extended, 5.2 2 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Self-Diagnostics >> Diagnostic Tests >> DTC P0133: 1/1 O2 Sensor Slow Response
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DTC P0133: 1/1 O2 Sensor Slow Response

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 or primary oxygen sensor. 1/1 oxygen sensor slow response is monitored with engine temperature more than 147°F (64°C), after reaching vehicle speed of 10 MPH, throttle is off idle for 2 minutes, vehicle is brought to stop and allowed to idle with transmission in Drive. DTC may be stored in Powertrain Control Module (PCM) if 1/1 oxygen sensor signal voltage is switching from less than .27 volt to more than .62 volt and back fewer times than required. Possible causes are: exhaust leak, 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  11.
  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  6.
  3. Start engine and allow engine to idle. 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 .
  4. 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. This is the ground circuit for 1/1 oxygen sensor. PCM is located on firewall, near brake booster. 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 .
  5. 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, shut engine off. Replace 1/1 oxygen sensor. Perform TEST VER-5 . If voltage is .1 volt or more, repair high resistance on Tan/White wire on CNG models or Black/Dark Green wire on gasoline models between 1/1 oxygen sensor and PCM. Perform TEST VER-5 .
  6. Stop actuation of oxygen sensor heater test. 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. 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 .
  7. 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, go to next step. 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 .
  8. Start engine and allow engine to idle. Check for exhaust leaks between engine and 1/1 oxygen sensor. If no exhaust leaks exist, go to next step. If exhaust leaks exist, repair exhaust system as necessary. Perform TEST VER-5 .
  9. Shut engine off. Reinstall 1/1 oxygen sensor connector. 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. PCM is located on firewall, near brake booster. 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 Tan/White wire on CNG models or Black/Dark Green wire on gasoline models between 1/1 oxygen sensor and PCM. Perform TEST VER-5 .
  10. 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. 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, replace 1/1 oxygen sensor. Perform TEST VER-5 . 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 .
  11. Start engine and allow engine to idle. 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 .
  12. Turn ignition off. Inspect wiring harness and connectors between 1/1 oxygen sensor and PCM. PCM is located on firewall, near brake booster. Inspect 1/1 oxygen sensor connector and PCM connectors for corroded, pushed out, miswired or damaged terminals. Also, check for related Technical Service Bulletins (TSBs). If no problems and no related TSBs exist, test is complete. If any problems exist, repair wiring or connectors as necessary. Perform TEST VER-5 .
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