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DTC P0134: O2 Sensor 1/1 Stays At Center

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION  . For wiring diagram, see WIRING DIAGRAMS article.
NOTE: Monitored with engine running for more than 2 minutes and coolant temperature more than 170°F (77°C). Set condition is when upstream O2S 1/1 signal voltage is between .35-.55 volts for 1.5 minutes. Possible causes are: O2S 1/1 ground circuit open, O2S 1/1 signal circuit open, intermittent wiring harness failure, defective O2S 1/1 or defective PCM.
  1. Start engine and allow it to reach normal operating temperature. Using scan tool, set engine speed to 1500 RPM. Using scan tool, observe O2S 1/1 state. If O2S 1/1 state is switching, go to next step. If O2S 1/1 state is not switching, go to step  4 .
  2. Using scan tool, observe O2S 1/1 state. Wiggle O2S 1/1 wiring harness while observing scan tool. If O2S 1/1 state was not locked at center at any time, go to next step. If O2S 1/1 state was locked at center at any time, repair wiring harness where wiggling caused O2S 1/1 state to lock at center. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  3. Turn ignition off. Inspect O2S 1/1 electrical connectors and wiring. Clean/repair as necessary. If no problems were found, test is complete. If any problems were found, repair as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  4. Disconnect O2S 1/1 connector. O2S 1/1 is located upstream of catalytic converter. Inspect electrical connectors and clean/repair as necessary. Using a DVOM, check resistance between O2S 1/1 connector (harness side) sensor ground circuit (Black/Orange wire) and chassis ground. If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open O2S 1/1 sensor ground circuit. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  5. Inspect O2S 1/1 connector for corroded, damaged, pushed out or miswired terminals. If connector is okay, go to next step. If connector is not okay, repair or replace connector as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  6. Connect a jumper wire between O2S 1/1 connector (harness side) signal circuit (Black/Dark Green wire) and B+. Turn ignition on with engine off. Using scan tool, observe O2S 1/1 voltage. If voltage is one volt or less, go to next step. If voltage is more than one volt, replace O2S 1/1. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  7. Turn ignition off. Disconnect Powertrain Control Module (PCM) connector C1 (located nearest to front of vehicle). PCM is located to left of Power Distribution Center (PDC) in engine compartment. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check resistance of O2S 1/1 signal circuit between O2S 1/1 connector (harness side) (Black/Dark Green wire) and PCM connector C1 terminal No. 30 (Black/Dark Green wire). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open O2S 1/1 signal circuit. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  8. If no other potential causes are remaining, PCM is assumed to be defective. Replace PCM. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
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