Monitoring Conditions - Mazda RX-8 Manual

DTC P0126, P0128
DTC P0126 Insufficient coolant temperature for stable operation
DTC P0128 Coolant thermostat problem
DETECTION
CONDITION
POSSIBLE
CAUSE
DTC P0126
The PCM monitors the ECT after the engine start for a certain period. If the the
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ECT never exceeds 71 ° ° ° ° C {160 ° ° ° ° F} when the following conditions are met, the
PCM determines that the coolant thermostat is stuck open.

MONITORING CONDITIONS

Soak time: more than 6 hour
IAT: more than − − − − 10 ° ° ° ° C {14 ° ° ° ° F}
Vehicle speed: more than 10 km/h {6.2 mph}
LOAD: more than 21.9 %
DTC P0128
The PCM calculates the radiator heat radiation ratio while the following conditions
•
are met. If the calculated value exceeds the threshold, the PCM determines that the
coolant thermostat is stuck open.
MONITORING CONDITIONS
Soak time: more than 6 hour
IAT: more than − − − − 10 ° ° ° ° C {14 ° ° ° ° F}
ECT at engine start: less than 35 ° ° ° ° C {95 ° ° ° ° F}
Vehicle speed: more than 40 km/h {24.9 mph}
Diagnostic support note
This is a continuous monitor (Thermostat).
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The MIL illuminates if the PCM detects the above malfunction condition in two
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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.
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The DTC is stored in the PCM memory.
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Coolant thermostat malfunction
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VSS malfunction
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IAT sensor malfunction
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(w) Engine Diagnostics & Control
Page 92