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HOMESERVICE MANUALSMAZDA2008CX-7 TOURING, 2.3 3, AWDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISON-BOARD DIAGNOSTIC (ENGINE CONTROL SYSTEM) - (2 OF 5)DTC P0126, P0128[L3 WITH TC]DIAGNOSTIC PROCEDURE
2008 Mazda CX-7 Touring, 2.3 3, AWD

Diagnostic procedure

2008 Mazda CX-7 Touring, 2.3 3, AWDSECTION Diagnostic procedure
DTC P0126, P0128[L3 WITH TC] 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 Repair circuit malfunction for applicable DTCs.
No Go to the next step.
4 INSPECT COOLANT THERMOSTAT FOR WHETHER STUCK OPEN 
  • Perform coolant thermostat inspection.
  • Is coolant thermostat normal?
 Yes Inspect ECT sensor.
Replace ECT sensor if necessary, then go to the next step.
No Replace coolant thermostat, then go to the next step.
5 VERIFY MONITORING CONDITION FOR REPAIR VERIFICATION 
  • Make sure to reconnect all disconnected connectors.
  • Cool down engine.
    NOTE:
    • If workshop inside and outside temperature difference is significant, PCM might not operate thermostat monitor. Therefore, it is recommended to cool down engine out of workshop.
  • Turn ignition switch to ON (Engine off).
  • Clear the DTC from the PCM memory using the M-MDS.
  • Access ECT, IAT PIDs and make sure that each value is within following specifications.
    • ECT: below 36 °C {97 °F}  (for P0128 only)
    • IAT: above -10°C{14°F} 
    • Difference between ECT and IAT: below 6°C {43°F} 
  • 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 M-MDS 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 minutes  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 is38 minutes and ECT is 30 °C {86 °F}  , monitoring period is 8 minutes)  .
  • 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.
7 VERIFY TROUBLESHOOTING OF DTC P0128 COMPLETED 
  • Start engine and turn off E/L and A/C.
  • Access DIAGNOSTIC MONITORING TEST RESULTS using the M-MDS and monitor TEST #10: E1:80 (Heat radiation ratio) or #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 (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) and #10: El: 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.
8 VERIFY AFTER REPAIR PROCEDURE 
 Yes Go to the applicable DTC inspection.
No Troubleshooting completed.
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.