LEMON Manuals: Even more car manuals for everyone
Home >> Isuzu >> 1998 >> Trooper S, Standard >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 3.2L & 3.5L >> Self-Diagnostic Tests >> DTC P0146: Heated Oxygen Sensor (Ho2S) No. 3 Bank 1/Insufficient Activity (3.5L) >> Diagnostic Aids

Diagnostic Aids

An intermittent may be caused by a poor connection, rubbed through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness.

Start and run engine at part throttle in closed loop. Using scan tool, monitor signal voltage while wiggling HO2S related connectors. If a failure is induced, signal voltage will change form normal fluctuating voltage to a fixed voltage. A change in voltage will assist in isolating location of fault. DO NOT  solder HO2S wires.

  1. Perform On-Board Diagnostic (OBD) system check. See BASIC TESTING article. Go to next step.
  2. Start engine and allow it to reach normal operating temperature. Apply parking brake and increase engine speed to greater than 1200 RPM for 2 minutes. Using scan tool, observe HO2S No. 3, bank 1 parameter. If reading does not vary outside 425-475 mV range, go to step 4). If reading varies outside 425-475 mV range, turn engine off and go to next step.
  3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If DTC P0146 is set, go to next step. If DTC P0146 is not set, check for in intermittent problem. See DIAGNOSTIC AIDS  .
  4. Check for poor high or low signal circuit connections or damaged harness at HO2S No. 3, bank 1 harness connector. Repair as necessary. Retest system. If connection is okay, go to next step.
  5. Turn ignition off. Disconnect PCM harness connectors. Check for poor or damaged HO2S No. 3, bank 1 high (White wire) or low (Red wire) signal circuit connections at PCM harness connector. Repair as necessary. Retest system. If connections are okay, go to next step.
  6. Turn ignition off. Disconnect PCM harness connectors. Check for poor HO2S No. 3, bank 1 high (White wire) or low (Red wire) signal circuit connections at PCM harness connectors or damaged harness. Repair as necessary. Retest system. If connections are okay, go to next step.
  7. Turn ignition on. Disconnect HO2S No. 3, bank 1 connector. Connect fused jumper wire between ground and high (White wire) and low (Red wire) signal circuit of HO2S No. 3, bank 1 (PCM side). If scan tool display is 0-10 mV, replace HO2S No. 3, bank 1. If display is not as specified, replace PCM. Retest system.
scientia non olet · About LEMON Manuals