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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 334 (On-Board Diagnostic (Engine Control System (AJ)) >> DTC P0126, P0128 >> Diagnostic procedure

Diagnostic procedure

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DTC P0126, P0128 [AJ] 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 (Engine cooling system related) been recorded?
Yes Go to the next step.
No Record FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS on repair order, then go to the next step.
2 VERIFY RELATED REPAIR INFORMATION AVAILABILITY 
  • Check for related Service Bulletins and/or online 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 INSPECT FOR OTHER DTCS 
  • Have other DTCs been stored?
Yes Go to appropriate DTC troubleshooting procedure, then go to the next step.
(See DTC TABLE .)
No Go to the next step.
4 INSPECT COOLANT THERMOSTAT IS WHETHER STUCK OPEN 
Yes Replace coolant thermostat, then go to the next step.
(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION .)
No Inspect ECT sensor.
(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION .)
5 VERIFY MONITORING CONDITION FOR REPAIR VERIFICATION 
  • Make sure to reconnect all disconnected connectors.
  • Cool down engine.
    NOTE:
    • If temperature difference inside/outside workshop is significant, PCM might not operate thermostat monitor. Therefore, it is recommended to cool down engine out of workshop.
  • Turn the ignition switch to the ON position.
  • Clear the DTC from the PCM memory using the WDS or equivalent.
  • Access ECT, IAT PIDs and make sure that each value is within following specifications.
    • ECT: 36 °C {97 °F} or below  (for P0128 only)
    • IAT: -10°C {14°F} or above 
    • Difference between ECT and IAT: 6°C {43°F} or below 
  • Is there any PID that is out of specification?
Yes Take corrective action (e.g. cool down engine), then repeat this step.
No Go to the next step for DTC P0126 or go to step 7 for DTC P0128.
6 VERIFY TROUBLESHOOTING OF DTC P0126 COMPLETED 
  • Start engine and turn off E/L and A/C.
  • Access DIAGNOSTIC MONITORING TEST RESULTS using the WDS or equivalent and monitor TEST#10: E1: 81 (ECT).
    NOTE:
    • This test requires actual driving. Chassis roller cannot be used for this test.
    • During test drive, constant speed should be maintained, although 2 or 3 stops during every 5 min  of driving time (e.g. for traffic signals) is acceptable. Stop-and-go (e.g. in case of traffic congestion) is not acceptable during the test period.
    • Test period depends on ECT at engine start. (e.g. if ECT is -10°C {14°F}  , monitoring period is 38 min  and ECT is 30 °C {86 °F}  , monitoring period is 8 min) 
  • Verify TEST #10: E1: 81 (ECT) value.
  • Is value above minimum value?
Yes Go to Step 8.
No Replace PCM, then go to Step 8.
(See PCM REMOVAL/INSTALLATION .)
7 VERIFY TROUBLESHOOTING OF DTC P0128 COMPLETED 
  • Start engine and turn off E/L and A/C.
  • Access DIAGNOSTIC MONITORING TEST RESULTS using the WDS or equivalent and monitor TEST #10: E1: 80 (Heat radiation ratio) or #10: E1: 1 (ECT).
    NOTE:
    • This test requires actual driving. Chassis roller cannot be used for this test.
    • During test drive, constant speed should be maintained, although 2 or 3 stops (e.g. for traffic signals) is acceptable. Stop-and-go (e.g. in case of traffic congestion) is not acceptable during the test period.
  • Verify TEST #10: E1: 80 (Heat radiation ratio) or #10: E2: 81 (ECT) value.
  • Are value of TEST#10: E1: 80 (Heat radiation ratio) below maximum value and value of TEST#10: E1: 81 (ECT) above minimum value?
Yes Go to the next step.
No Replace PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION .)
8 VERIFY AFTER REPAIR PROCEDURE 
Yes Go to the applicable DTC inspection.
(See DTC TABLE .)
No Troubleshooting completed.