DTC P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
HINT: This DTC relates to the thermostat.
DESCRIPTION This DTC is set when the Engine Coolant Temperature (ECT) does not reach 75C (167F) despite sufficient engine warm-up time
DTC No. |
DTC Detection Condition |
Trouble Area |
P0128 |
Conditions (a), (b) and (c) are met for 5 seconds (2 trip
detection logic):
|
|
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 75C (167F), the ECM checks the actual ECT. If the actual ECT is less than 75C (167F), 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. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction
1 CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0128)
Result
HINT: If any DTCs other than P0128 are output, troubleshoot those DTCs first.
2 CHECK COOLING SYSTEM
3 INSPECT THERMOSTAT
Standard: 80 to 84C (176 to 183F)
HINT: In addition to the above check, confirm that the valve is completely closed when the temperature is below the standard.
REPLACE ECM
Navigation check mode
HINT:
This mode displays GPS satellite information.
Illustrations may differ from the actual vehicle depending
on the device settings and options. Therefore, some
detailed areas may not be shown exactly the same as on
the actual vehicle.
1. ENTER DIAGNOSTIC MODE ( )
2. NA ...
Changing the vehicle-to-vehicle distance
Pressing the button changes the
vehicle-to-vehicle distance as follows:
Long
Medium
Short
The vehicle-to-vehicle distance is
set automatically to long mode
when the engine switch is turned to
IGNITION ON mode.
If a vehicle is running ahead of
you, the preceding vehicle mark
w ...
Disassembly
1. REMOVE OIL PUMP RELIEF VALVE
(A) using a 27 mm socket wrench, remove the relief
valve plug.
(B) remove the valve spring and oil pump relief valve.
2. REMOVE OIL PUMP COVER
(a) Remove the 8 bolts, oil pump cover and oil pump
rotor set. ...