DTC P0131: O2 Sensor 1/1 Shorted To Ground
NOTE:
For connector terminal ID, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article.
NOTE:
The O2 sensor 1/1 is referred to as upstream oxygen sensor in this test. Upstream oxygen sensor operation is monitored with engine coolant temperature more than 170°F (76.7°C) after ignition was last turned on, after a cold start, engine coolant temperature is less than 98°F (36.6°C) and ambient/battery temperature sensor reading is within 27°F (-2.7°C) of engine coolant temperature. DTC may be stored in Powertrain Control Module (PCM) if upstream oxygen sensor signal voltage is less than .156 volt for 28 seconds after starting the engine. Possible causes are: dirty or wet connections causing voltage tracking, defective upstream oxygen sensor, defective PCM, or defective connectors or wiring.
- Turn ignition on with engine off. Using scan tool, read Diagnostic Trouble Codes (DTCs). If global good trip counter is displayed and equal to zero, go to next step. If global good trip counter is not displayed or displayed with a value, go to step 5.
- Using scan tool, monitor upstream oxygen sensor voltage. Upstream oxygen sensor voltage may also be referred to as 1/1 O2 sensor voltage. While monitoring oxygen sensor voltage, disconnect oxygen sensor connector. If upstream oxygen sensor voltage changes from less than one volt to more than 4.5 volts, replace oxygen sensor. Perform TEST VER-5A . If upstream oxygen sensor voltage does not change as specified, go to next step.
- Turn ignition off. Disconnect connector at upstream oxygen sensor. Upstream oxygen sensor is located on the exhaust manifold. Disconnect PCM connectors. PCM is located at driver's side front corner of engine compartment, between battery and fender. Using ohmmeter, check resistance between upstream oxygen sensor connector (harness side) terminals No. 3 (Black/Orange wire) and No. 4 (Black/Dark Green wire). If resistance is less than 5 ohms, repair short between Black/Orange and Black/Dark Green wires. Perform TEST VER-5A . If resistance is 5 ohms or more, go to next step.
- Ensure connectors are still disconnected at PCM. Using ohmmeter, check resistance between ground and upstream oxygen sensor connector (harness side) terminal No. 4 (Black/Dark Green wire). If resistance is 5 ohms or more, replace PCM. Perform TEST VER-5A . If resistance is less than 5 ohms, repair short to ground on Black/Dark Green wire between PCM and upstream oxygen sensor. Perform TEST VER-5A .
- Inspect wiring and connectors between upstream oxygen sensor and PCM. Inspect related wiring harnesses and connectors. Refer to Technical Service Bulletins (TSBs) for related problems. If no problems exist, test is complete. If any problems exist, repair wiring or connectors as necessary. Perform TEST VER-5A .