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2008 - MX-5 - Engine

DTC P0133 [LF]



DTC P0133

Front HO2S circuit problem

DETECTION CONDITION

  • The PCM monitors the peak differential value of oxygen sensor signal after A/F fluctuation being provided when the following conditions are met. If the peak differential value is lower than the threshold value.

  • The PCM determines that front HO2S circuit is slow.

    • MONITORING CONDITIONS
    • HO2S heater, HO2S, and TWC Repair Verification Drive Mode

    • Following conditions are met:

      • Front HO2S heater monitor is completed.

      • Fuel system loop status is closed loop fuel control.

    • Engine speed: 1,750—3,500 rpm.

    • Charging efficiency: 25—63 % (at engine speed: 2,500 rpm).

    • Engine coolant temperature above 70 °C {158 °F}

    Diagnostic support note
  • This is an intermittent monitor. (HO2S)

  • The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.

  • DIAGNOSTIC MONITORING TEST RESULTS is available.

  • PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.

  • FREEZE FRAME DATA is available.

  • The DTC is stored in the PCM memory.

POSSIBLE CAUSE

  • Front HO2S deterioration

  • Front HO2S malfunction

  • Front HO2S looseness

  • Pressure regulator (built-in fuel pump unit) malfunction

  • Fuel pump malfunction

  • Clogged or restricted fuel filter (built-in fuel pump unit)

  • Fuel leakage in fuel line between fuel distribution pipe and fuel pump

  • Exhaust system leakage

  • Purge solenoid valve malfunction

  • Improper connection purge solenoid hose

  • Insufficient compression

  • Engine malfunction (Engine coolant leakage)


Diagnostic procedure

STEP

INSPECTION

ACTION

1

VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED
  • Have FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (HO2S related) been recorded?

Yes

Go to the next step.

No

Record the FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.

2

VERIFY RELATED REPAIR INFORMATION AVAILABILITY
  • Verify related Service Bulletins and/or on-line repair information availability.

  • Is any related repair information available?

Yes

Perform repair or diagnosis according to the available repair information.

  • If the vehicle is not repaired, go to the next step.

No

Go to the next step.

3

VERIFY RELATED PENDING AND STORED DTC
  • Turn the ignition switch off, then to the ON position (Engine off).

  • Verify the pending or stored DTCs using the M-MDS.

  • Is DTC P0443 also present?

Yes

Go to DTC P0443 troubleshooting procedures, then go to Step 13.

No

Go to the next step.

4

IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA
  • Is DTC P0133 on FREEZE FRAME DATA?

Yes

Go to the next step.

No

Go to troubleshooting procedures for DTC on FREEZE FRAME DATA.

(See DTC TABLE [LF].)

5

INSPECT INSTALLATION OF FRONT HO2S
  • Inspect if the front HO2S is loosely installed.

  • Is the front HO2S installed securely?

Yes

Go to the next step.

No

Retighten the front HO2S, then go to Step 10.

(See REAR HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [LF].)

6

INSPECT GAS LEAKAGE FROM EXHAUST SYSTEM
  • Visually inspect if there is any gas leakage between the exhaust manifold and front HO2S.

  • Is there gas leakage?

Yes

Repair or replace any malfunctioning exhaust part, then go to Step 10.

No

Go to the next step.

7

INSPECT FRONT HO2S

Yes

Replace the front HO2S, then go to Step 10.

(See FRONT HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [LF].)

No

Go to the next step.

8

INSPECT FUEL LINE PRESSURE

Yes

Go to the next step.

No

Repair or replace any malfunctioning exhaust part, then go to Step 10.

9

INSPECT SEALING OF ENGINE COOLANT PASSAGE

Yes

Repair or replace malfunctioning part according to the inspection result. Then go to the next step.

No

Go to the next step.

10

VERIFY TROUBLESHOOTING OF DTC P0133 COMPLETED
  • Make sure to reconnect all disconnected connectors.

  • Clear the DTC from the PCM memory using the M-MDS or equivalent.

  • Perform the “PCM Adaptive Memory Produce Drive Mode” and “HO2S heater, HO2S, and TWC Repair Verification Drive Mode“.

    (See OBD-II DRIVE MODE [LF].)

  • Is the PENDING CODE for this DTC present?

Yes

Replace the PCM, then go to the next step.

(See PCM REMOVAL/INSTALLATION [LF].)

No

Go to the next step.

11

VERIFY AFTER REPAIR PROCEDURE

Yes

Go to the applicable DTC inspection.

(See DTC TABLE [LF].)

No

DTC troubleshooting completed.




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