Dtc P0116 Engine Coolant Temperature Circuit Range / Performance Problem

Engine. Lexus Gs430, Gs300. Uzs190 Grs190
3Uz-Fe Engine Control System. Lexus Gs430, Gs300. Uzs190 Grs190

DESCRIPTION

MONITOR DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0116)

INSPECT THERMOSTAT

DTC P0116 Engine Coolant Temperature Circuit Range / Performance Problem


DESCRIPTION


  1. Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System. Dtc P0116 Engine Coolant Temperature Circuit Range / Performance Problem
    A thermistor is built into the Engine Coolant Temperature (ECT) sensor and changes the resistance value according to the engine coolant temperature.
    The structure of the sensor and connection to the ECM is the same as the Intake Air Temperature (IAT) sensor.
    HINT:
    If the ECM detects the DTC P0115, P0117 or P0118, it operates the fail-safe function in which the ECT is assumed to be 80°C (176°F).

DTC No.
DTC Detection Condition
Trouble Area
P0116
  1. If ECT is 35 to 60°C (95 to 140°F) when engine is started, and if conditions (a) and (b) are met:
    1. (a) Vehicle has accelerated and decelerated
    2. (b) ECT remains within 3°C (5.4°F) of the initial ECT (2 trip detection logic)
  1. Cooling system
  1. ECT sensor
P0116
  1. If ECT is more than 60°C (140°F) when engine is started and the vehicle has accelerated and decelerated
  1. If ECT sensor records an ECT variation below 1°C (1.8°F) successively 6 times (6 trip detection logic)
  1. Cooling system
  1. ECT sensor

MONITOR DESCRIPTION

The ECT sensor is used to monitor the engine coolant temperature. The ECT sensor has a thermistor that varies its resistance depending on the temperature of the engine coolant. When the coolant temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. The variations in resistance are reflected in the output voltage from the sensor. The ECM monitors the sensor voltage and uses this value to calculate the ECT. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the ECT sensor and sets a DTC.
Examples:
  1. Upon starting the engine, the ECT is between 35°C (95°F) and 60°C (140°F). If after driving for 250 seconds, the ECT still remains within 3°C (5.4°F) of the starting temperature, a DTC will be set (2 trip detection logic).
  2. Upon starting the engine, the ECT is over 60°C (140°F). If, after driving for 250 seconds, the ECT still remains within 1°C (1.8°F) of the starting temperature, a DTC will be set (6 trip detection logic).

WIRING DIAGRAM


Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System. Dtc P0116 Engine Coolant Temperature Circuit Range / Performance Problem


INSPECTION PROCEDURE

HINT:
  1. If DTC P0115, P0116, P0117, P0118 and P0125 are output simultaneously, ECT sensor circuit may be open or shorted. Perform the troubleshooting of DTC P0115, P0117 or P0118 first.
  2. Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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.
1.CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0116)

Result:

Display (DTC output)
Proceed to
P0116
A
P0116 and other DTCs
B


B
GO TO RELEVANT DTC CHART
A


2.INSPECT THERMOSTAT

  1. Remove the thermostat (Click here).

  1. Check the valve opening temperature of the thermostat.

    Standard:
    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.


NG
REPLACE THERMOSTAT
OK

REPLACE ENGINE COOLANT TEMPERATURE SENSOR