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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 P0131: 1/1 O2 Sensor Shorted To Ground
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DTC P0131: 1/1 O2 Sensor Shorted To Ground

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 is monitored at a cold start, engine coolant temperature is less than 98°F (37°C) and battery temperature sensor reading is within 27 °F (-2.8°C) of engine coolant temperature and engine coolant temperature is more than 170°F (77°C) the last time ignition was on. DTC may be stored in Powertrain Control Module (PCM) if 1/1 oxygen sensor signal voltage is less than .156 volt for 28 seconds after engine is started. Possible causes are: defective 1/1 oxygen sensor, defective PCM, 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  5.
  2. Ensure ignition is on with engine off. Using scan tool, monitor 1/1 oxygen sensor voltage while disconnecting 1/1 oxygen sensor connector. The 1/1 oxygen sensor is located on exhaust pipe in front of catalytic converter. If 1/1 oxygen sensor voltage does not change from less than one volt to more than 4.5 volts, go to next step. If 1/1 oxygen sensor voltage changes from less than one volt to more than 4.5 volts, replace 1/1 oxygen sensor. Perform TEST VER-5 .
  3. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall, near brake booster. Ensure 1/1 oxygen sensor connector is still disconnected. Using ohmmeter, check resistance between terminals No. 3 (Black/Light Blue wire) and No. 4 (Tan/White wire on CNG models or Black/Dark Green wire on gasoline models) on 1/1 oxygen sensor connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair Black/Light Blue and Tan/White wire (CNG models) or Black/Dark Green wire (gasoline models) between 1/1 oxygen sensor and PCM as they are shorted together. Perform TEST VER-5 .
  4. Ensure PCM connectors and 1/1 oxygen sensor connector are still disconnected. Using ohmmeter, check resistance between ground and terminal No. 4 (Tan/White wire on CNG models or Black/Dark Green wire on gasoline models) on 1/1 oxygen sensor connector. If resistance is 5 ohms or more, replace PCM. Perform TEST VER-5 . If resistance is less than 5 ohms, repair short to ground on Tan/White wire (CNG models) or Black/Dark Green wire (gasoline models) between 1/1 oxygen sensor and PCM. Perform TEST VER-5 .
  5. Turn ignition off. Inspect wiring harness and connectors between 1/1 oxygen sensor and PCM. The 1/1 oxygen sensor is located on exhaust pipe in front of catalytic converter. 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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