2014 Mazda 3 SV, Automatic TransFACTORY OEM SERVICE PROCEDURE

No. 17 Cooling System Concerns-Overheating: Notes

NO. 17 COOLING SYSTEM CONCERNS-OVERHEATING DESCRIPTION AND POSSIBLE CAUSES (SKYACTIV-G 2.0, SKYACTIV-G 2.5)

17  COOLING SYSTEM CONCERNS-OVERHEATING 
DESCRIPTION 
  • Engine runs at higher than normal temperature/overheats.
POSSIBLE CAUSE 
  • Engine heat generation amount is excessive
    • Engine speed is high and remains high for continuous long periods
  • PCM DTC is stored
  • Improper operation of A/C system
  • Insufficient air blow volume
    • Cooling fan inoperative
    • Fan rotation speed decreases (such as generator malfunction) due to battery voltage decrease
  • Cooling system cap malfunction
  • Cooling fan motor assembly malfunction
  • Cooling fan motor connector malfunction
  • Improper indication of low engine coolant temperature indicator light and/or high engine coolant temperature warning light
    • ECT sensor No. 1 malfunction
    • Instrument cluster malfunction
  • Blown fuse
  • Engine coolant system malfunction
    • Improper engine coolant level
    • Engine coolant performance deterioration
    • Coolant leakage (engine internal, external)
    • Improper water/anti-freeze mixture
    • Thermostat malfunction (not fully open)
    • Radiator malfunction (clogging)
  • Leakage around heater unit in passenger compartment
  • Drive belt damage
CAUTION:
  • Verify the malfunction symptom according to not only the PID value but also the symptom troubleshooting.
RELATED PIDS

Item (definition) Unit/Condition Definition Condition/Specification (Reference)
ECT °C, °F Engine coolant temperature
  • Displays ECT
V ECT sensor No. 1 voltage
  • ECT is 20 °C {68 °F}: Approx. 3.10 V
  • ECT is 40 °C {104 °F}: Approx. 2.16 V
  • ECT is 60 °C {140 °F}: Approx. 1.40 V
  • ECT is 80 °C {176 °F}: Approx. 0.87 V
  • ECT is 100 °C {212 °F}: Approx. 0.54 V
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  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
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