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Home >> Mazda >> 2002 >> Millenia S >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 2.3L >> Diagnostic Tests >> DTC P0134: Front Right Ho2S Circuit, No Activity Detected & P0154: Front Left Ho2S Circuit, No Activity Detected >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

  1. Ensure FFD has been recorded. See FREEZE FRAME DATA (FFD)  . If FFD has been recorded, go to next step. If FFD has not been recorded, record FFD on repair order, then go to next step.
  2. Verify related repair information is available. Check for related service bulletins and/or on-line repair information availability. If information is available, perform repair or diagnosis according to repair information, if vehicle is not repaired, go to next step. If information is not available, and vehicle is not repaired, go to next step.
  3. Verify related pending and stored DTCs. Turn ignition off, then on (engine off). Verify pending and stored DTCs using WDS or equivalent scan tool. See RETRIEVING DIAGNOSTIC TROUBLE CODES  . If DTCs P1170 and P1173 are present, go to appropriate DTC trouble shooting procedures. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If DTCs P1170 and P1173 are not present, go to next step.
  4. Identify trigger DTC for FFD. See FREEZE FRAME DATA (FFD)  . If DTC P0134, P0140 or P0154 are on FFD, go to next step, If they are not on FFD, go to trouble shooting procedures for DTC on FFD. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  .
  5. Verify current input signal status. Warm engine. Access O2S11 for P0134 or O2S21 for P0154 PID using WDS or equivalent scan tool. See PARAMETER IDENTIFICATION (PID) ACCESS  . Check PID under following accelerator pedal conditions (in Park). If PIDs are readings okay, more than 0.55 volts when suddenly depressing accelerator pedal (rich condition) or less than 0.55 volts, just after release of accelerator pedal (lean condition). Go to step  8 . If readings are not within specification, go to next step.
  6. Inspect installation of front HO2S. Check if front HO2S is loosely installed. If sensor is installed securely, go to next step. If sensor is not installed securely, tighten sensor, then go to step  10 .
  7. Inspect exhaust for leaks. Check for an exhaust leak between exhaust manifold and front HO2S. If a leak exists, repair or replace any faulty exhaust parts, then go to step  10 . If an exhaust leak does not exist, inspect the following harnesses for open or short to ground:
    • Right front HO2S terminal "A" (harness side) to PCM terminal "3I" (harness side).
    • Left front HO2S terminal "A" (harness side) to PCM terminal "3M" (harness side).
    Repair or replace harness as necessary. If all items are okay, replace faulty sensor, then go to step  10 .
    8. 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 cap and turn slowly.
  8. Inspect sealing of engine coolant passage. Remove radiator cap. Implement procedure to bleed air from engine coolant, see COOLING SYSTEM BLEEDING in REMOVAL, OVERHAUL & INSTALLATION article, idle engine. If there are any small bubbles, which make engine coolant white at the filler opening, air is getting in from poor sealing on head gasket or other areas between combustion chamber and engine coolant passage. Repair or replace faulty parts, then go to step  10 . If there are no small bubbles, go to next step.
  9. Inspect engine compression. See MECHANICAL INSPECTION in BASIC DIAGNOSTIC PROCEDURES article. If compression is okay, go to next step. If compression is not okay, implement engine overhaul, then go to next step.
  10. Verify trouble shooting. Reconnect all disconnected connectors. Turn ignition on, engine off. Clear DTC from PCM memory using WDS or equivalent scan tool. See CLEARING DIAGNOSTIC TROUBLE CODES  . Start engine. Access RPM and ECT PIDs using WDS or equivalent scan tool. See PARAMETER IDENTIFICATION (PID) ACCESS  . Verify ECT PID is reading greater than 140°F (60°C). Increase engine speed greater than 1500 RPM (RPM PID reading) for more than 95 seconds. If pending code is the same, replace PCM, then go to next step. If pending code is not the same, go to next step.
  11. Perform after repair procedure. See AFTER REPAIR PROCEDURE  . If there are any DTCs present, go to applicable DTC inspection. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If there are no DTCs present, trouble shooting is complete.
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