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
Registration
1. DESCRIPTION OF CODE REGISTRATION
HINT:
The key has 2 codes: The key code (immobiliser code)
and the wireless code. Both of these codes need to be
registered. Refer to page for the wireless code
registration procedures.
When adding master keys or sub keys (Additional
registration) ...
Dtc check / clear
1. DTC CHECK (NORMAL MODE)
NOTICE:
When the diagnostic system is switched from the
normal mode to the check mode, all the DTCs and
freeze frame data recorded in the normal mode will
be erased. So before switching modes, always check
the DTCs and freeze frame data, and note the ...
Air Mix Damper Position Sensor Circuit (Passenger Side)
DESCRIPTION
This sensor detects the position of the air mix control servo motor (air mix
damper) and sends the
appropriate signals to the A/C amplifier. The position sensor is built in the
air mix control servo motor. The
position sensor's resistance changes as the air mix control servo m ...