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Home › Mazda › 2002 › MPV ES › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0134 Or DTC P0154 › Diagnostic Procedures

Diagnostic Procedures

  1. Record freeze frame data. Check for service bulletins and on-line information. Repair as necessary. After repair, go to next step.
    NOTE: If fuel monitor DTCs P0131, P0132, P0151 or P0152 is stored, ignore until P0134 or P0154 is repaired.
  2. Verify Related Pending & Stored DTCs -  Turn ignition off, then on (engine off). Using scan tool, check for pending and stored DTCs. If no other DTC is present, go to next step. If any other DTC is present, diagnose and repair first. Refer to DIAGNOSTIC TROUBLE CODE IDENTIFICATION .
  3. Identify Trigger DTC For FREEZE FRAME DATA -  Check for presence of DTC P0134 or P0154 on FREEZE FRAME DATA. If either DTC is present, go to next step. If either DTC is not present on FREEZE FRAME DATA, go to trouble shooting procedure for DTC that triggered FREEZE FRAME DATA. Refer to DIAGNOSTIC TROUBLE CODE IDENTIFICATION .
  4. Verify Current Input Signal Status -  Start engine. Warm up to normal operating temperature. Using scan tool, access O2S11 (P0134) or O2S21 (P0154). Verify PID while racing engine in park or neutral. If PID reading is more than .55 volt when accelerator pedal is suddenly depressed (rich condition) and less than .55 volt when accelerator pedal is released (lean condition), go to step  7. If voltage is not as specified, go to next step.
  5. Inspect Installation Of HO2S (Front) -  Check front HO2S installation. If front HO2S is tight, go to next step. If front HO2S is loose, tighten front HO2S. After repair, go to step  9.
  6. Inspect Gas Leakage From Exhaust System -  Check for exhaust leaks upstream from front HO2S. If any leaks are present, repair or replace faulty exhaust system parts. After repair, go to step  9. If leaks are not present, check for open or short in circuit between:
    • Right front HO2S 4-pin harness connector terminal "A" and PCM 104-pin harness connector terminal No. 60 (Light Green/Red wire). See Figure and Fig 1 .
    • Left front HO2S 4-pin harness connector terminal "A" and PCM 104-pin harness connector terminal No. 87 (White wire).

    If problem is present, repair as necessary. See appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS. If problem is not present, replace suspect front HO2S. After repair, go to step  9.

    Fig 1: Identifying Front HO2S 4-Pin Harness Connector Terminals
    G00143779Courtesy of MAZDA MOTORS CORP.
    WARNING: Removing radiator cap when radiator is hot is dangerous. Scalding coolant and steam may shoot out and cause serious injury. When removing radiator cap, wrap a thick cloth around and turn it slowly.
    NOTE: Large bubbles are normal since they are remaining air coming out from engine coolant passage.
  7. Inspect Sealing Of Engine Coolant Passage - Check cooling system for combustion gasses. Remove radiator cap. Bleed air from cooling system. Start engine and let idle. Check for small bubbles which make coolant white at filler neck. If combustion gasses are not present, go to next step. If combustion gasses are present, repair or replace faulty parts as necessary. After repair, go to step  9.
  8. Inspect Engine Compression -  Check engine compression. See MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES article. If compression is okay, go to next step. If compression is low, overhaul engine. See appropriate MECHANICAL article in ENGINES. After repair, go to next step.
  9. Verify Trouble Shooting Of DTC P0134 Or P0154 Completed -  Reconnect all components. Turn ignition on, engine off. Using scan tool, clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Access RPM and ECT PIDs. Start engine. Ensure ECT PID is more than 158°F (70°C). Increase engine speed to more than 1500 RPM for more than 95 seconds. Recheck DTCs. If DTC P0134 or P0154 is present, replace PCM. After repair, go to next step. If DTC P0134 or P0154 is not present, go to next step.
  10. Verify After Repair Procedure -  Using scan tool, perform After Repair Procedure. See AFTER REPAIR PROCEDURE . If no other DTCs are present, testing is complete. If any other DTC is present, go to applicable test and repair.
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