P0128

P0128 THERMOSTAT FUNCTION

DTC Logic

DTC Detection Logic

NOTE: If DTC P0128 is displayed with DTC P0300, P0301, P0302, P0303 or P0304, first perform the trouble diagnosis for DTC P0300, P0301, P0302, P0303, P0304. Refer to EC-242, "DTC Logic". P0300

Engine coolant temperature has not risen enough to open the thermostat even though the engine has run long enough.
This is due to a leak in the seal or the thermostat stuck open.

DTC Confirmation Procedure

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Diagnostic Procedure

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Component Inspection