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Home >> Mazda >> 2006 >> MPV ES >> Repair and Diagnosis >> Engine Performance >> System >> On-Board Diagnostic [Engine Control System (AJ)] >> DTC P0126, P0128 >> Notes

DTC P0126, P0128: Notes

DTC P0126, P0128 [AJ] DETECTION CONDITION AND POSSIBLE CAUSES

DTC P0126
DTC P0128
Coolant thermostat stuck open
DETECTION CONDITION  DTC P0126
  • If the ECT signal never exceeds 71 °C {160°F}  after engine start for specified period, PCM determines that the coolant thermostat is stuck open.

    MONITORING CONDITIONS 

    • IAT: Above -10°C {14°F} 
    • Vehicle speed: over 9.4 km/h {5.8 mph} 

DTC P0128 
  • PCM monitors MAF, IAT, VSS and EAT signals and calculates radiator's heat radiation ratio while following monitoring conditions are met. If calculated value exceeds threshold, PCM determines that the coolant thermostat is stuck open.

    MONITORING CONDITIONS 

    • ECT at engine start: Below 36°C {97°F} 
    • IAT: Above -10°C {14°F} 
    • Difference between ECT at engine start and minimum IAT: Below 6°C {43°F} 
    • Vehicle speed: over 9.4 km/h {5.8 mph} 

Diagnostic support note 

  • This is an intermittent monitor (Engine cooling system).
  • 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.
  • PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
  • DIAGNOSTIC MONITORING TEST RESULTS is available.
  • FREEZE FRAME DATA is available.
  • DTC is stored in PCM memory.
POSSIBLE CAUSE 
  • ECT sensor malfunction
  • Coolant thermostat malfunction
  • PCM malfunction