Hint:
This dtc relates to the thermostat.
Description
This dtc is set when the engine coolant temperature (ect) does not reach 75°c (167°f) despite sufficient engine warm-up time having elapsed.
Monitor description
The ecm estimates the ect based on the starting temperature, engine loads, and engine speeds. The ecm then compares the estimated temperature with the actual ect. When the estimated ect reaches 75°c (167°f), the ecm checks the actual ect. If the actual ect is less than 75°c (167°f), the ecm interprets this as a malfunction in the thermostat or the engine cooling system and sets the dtc.
Monitor strategy
Typical enabling conditions
Typical malfunction thresholds
Inspection procedure
Hint:
Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
Hint:
If any dtcs other than p0128 are output, troubleshoot those dtcs first.
Standard value: 80 to 84°c (176 to 183°f)
Hint:
In addition to the above check, confirm that the valve is completely closed when the temperature is below the standard.
Diagnosis system
Description
Air conditioning system data and the diagnostic
trouble codes (dtcs) can be read through the
data link connector 3 (dlc3) of the vehicle. When
the system seems to be malfunctioning, use the
intelligent tester to check for malfunctions and
perform troubleshooting.
...
Transmission fluid temperature sensor "A" circuit
Description
The automatic transmission fluid (atf) temperature sensor converts the atf
temperature into a
resistance value which is input into the ecm.
The ecm applies a voltage to the temperature sensor through ecm terminal tho1.
The sensor resistance changes with the atf temperature. ...
Diagnosis system
Description
The occupant classification ecu controls the functions of
the occupant classification system on the vehicle. Data
of the occupant classification system can be read in the
data link connector 3 (dlc3) of the vehicle. When the
system seems to be malfunctioning, use the intelligen ...