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Home >> Mazda >> 2012 >> 6 i Touring >> Repair and Diagnosis >> External Pages >> Different car >> Section 634 (On-Board Diagnostic (Engine Control System L5) (2 Of 5)) >> DTC P0126:00, P0128:00 [L5] >> Notes

DTC P0126:00, P0128:00 [L5]: Notes

WARNING: This page is about a different car, the 2009 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.
DETECTION CONDITIONS & POSSIBLE CAUSES

DTC P0126:00 Thermostat stuck open
DTC P0128:00 
DETECTION CONDITION  P0126:00 
  • If the ECT signal never exceeds threshold (depend on minimum IAT) after engine start for specified period, the PCM determines that the thermostat is stuck open.

    MONITORING CONDITIONS 

    • IAT above -10°C{14°F} 
    • Vehicle speed, over 40 km/h {25 mph} 
    • Absolute load. above 14 % 

P0128:00 
  • The PCM monitors MAF, IAT, VSS and ECT signals and calculate radiator's heat radiation ratio while following monitoring conditions are met If calculated value exceeds threshold, the PCM determines that the thermostat is stuck open

    MONITORING CONDITIONS 

    • IAT above -10°C{14°F} 
    • ECT at engine start: below 52°C {126°F} 
    • Vehicle speed, over 40 km/h {25 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
  • FREEZE FRAME DATA is available
  • The DTC is stored in the PCM memory.
POSSIBLE CAUSE 
  • Thermostat malfunction
  • ECT sensor malfunction
  • Cooling system malfunction
  • PCM malfunction