Lexus NX: Engine Coolant Temperature Circuit Range / Performance (P0116)

Lexus NX Service Manual / Engine & Hybrid System / 2ar-fxe (engine Control) / Sfi System / Engine Coolant Temperature Circuit Range / Performance (P0116)

DESCRIPTION

Refer to DTC P0115.

Click here

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory
P0116	Engine Coolant Temperature Circuit Range / Performance	Either of the following conditions is met (2 trip detection logic): When engine is started cold and warmed up, the engine coolant temperature sensor value does not change. After the warmed up engine is stopped and then next cold engine start is performed, the engine coolant temperature sensor value does not change.	Thermostat Engine coolant temperature sensor	Comes on	DTC stored

MONITOR DESCRIPTION

Engine Coolant Temperature Sensor Cold Start Monitor

When a cold engine start is performed and then the engine is warmed up, if the engine coolant temperature sensor value does not change, it is determined that a malfunction has occurred. If this is detected in 2 consecutive driving cycles, the MIL is illuminated and this DTC is stored.

Engine Coolant Temperature Sensor Soak Monitor

If the engine coolant temperature sensor value does not change after the warmed up engine is stopped and then the next cold engine start is performed, it is determined that a malfunction has occurred. If this is detected in 2 consecutive driving cycles, the MIL is illuminated and this DTC is stored.

MONITOR STRATEGY

Related DTCs	P0116: Engine coolant temperature sensor rationality (cold start monitor) P0116: Engine coolant temperature sensor rationality (soak monitor)
Required Sensors/Components (Main)	Engine coolant temperature sensor
Required Sensors/Components (Related)	-
Frequency of Operation	Once per driving cycle
Duration	-: Cold start monitor 10 seconds: Soak monitor
MIL Operation	2 driving cycles
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

All

Monitor runs whenever the following DTCs are not stored

None

Cold Start Monitor

All of the following conditions are met	-
Auxiliary battery voltage	10.5 V or higher
Time after engine start	1 second or more
Engine coolant temperature at engine start	Less than 60°C (140°F)
Soak time	0 seconds or more
Accumulated mass air flow	3699 g or more
Fuel cut	Off
Engine coolant temperature sensor circuit fail (P0115, P0117, P0118, P0125)	Not detected
Intake air temperature sensor circuit fail (P0112, P0113)	Not detected
Thermostat fail (P0128)	Not detected
Difference between engine coolant temperature at engine start and intake air temperature	Less than 40°C (72°F)

Soak Monitor

All of the following conditions are met	-
Auxiliary battery voltage	10.5 V or higher
Engine	Running
Soak time	5 hours or more
Either of the following conditions is met	(a) or (b)
(a) Engine coolant temperature	60°C (140°F) or higher
(b) Accumulated mass air flow	7398 g or more
Engine coolant temperature sensor circuit fail (P0115, P0117, P0118, P0125)	Not detected
Thermostat fail (P0128)	Not detected
Soak timer fail (P2610)	Not detected

TYPICAL MALFUNCTION THRESHOLDS

Cold Start Monitor

Engine coolant temperature sensor value change

Less than 5°C (9°F)

Soak Monitor

Difference between current engine coolant temperature sensor value and previous engine coolant temperature sensor value when engine stopped

Less than 5°C (9°F) (varies with engine coolant temperature of last trip engine stop)

COMPONENT OPERATING RANGE

Engine coolant temperature

Engine coolant temperature sensor value changes in accordance with actual engine coolant temperature

CONFIRMATION DRIVING PATTERN

Connect the Techstream to the DLC3.
Turn the power switch on (IG) and turn the Techstream on.
Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Coolant Temp.
Check that the engine coolant temperature is 60°C (140°F) or less.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the power switch off and wait for at least 30 seconds.
Turn the power switch on (IG) and turn the Techstream on [A].
Put the engine in inspection mode (maintenance mode).
Click here
Start the engine and idle it for 5 minutes or more [B].
HINT:

If the engine coolant temperature does not change by 5°C (9°F) or higher, the engine coolant temperature sensor is malfunctioning. It is not necessary to continue this procedure.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [C].
Read the pending DTCs.
HINT:
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0116.

Check the DTC judgment result.

Techstream Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

HINT:

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE or N/A, perform steps [D] and [E].

With the engine running, drive the vehicle at 40 km/h (25 mph) or more for a total of 5 minutes or more [D].
CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.
HINT:
- In the event of the drive pattern being interrupted (possibly due to factors such as traffic conditions), the drive pattern can be resumed.
- If the engine stops, further depress the accelerator pedal to restart the engine.
Check the DTC judgment result again [E].
HINT:

If the judgment result shows INCOMPLETE or N/A, perform steps [D] and [E] again.
If no pending DTC is output, perform a universal trip and check for permanent DTCs.
Click here
HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.

CAUTION / NOTICE / HINT

HINT:

If any of DTCs P0115, P0117, P0118 or P0125 are output simultaneously with DTC P0116, the engine coolant temperature sensor may have an open or a short circuit. Troubleshoot those DTCs first.
When the DTC is output, check the engine coolant temperature using the Techstream. Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Coolant Temp. If the Coolant Temp value is lower than the actual engine coolant temperature, the engine coolant temperature sensor circuit may be malfunctioning. In this case, check the wire harnesses and connectors (and those connections) between the ECM and the engine coolant temperature sensor first.
Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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.

PROCEDURE

1.	CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0116)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(e) Read the DTCs.

Powertrain > Engine and ECT > Trouble Codes

Result	Proceed to
DTC P0116 is output	A
DTC P0116 and other DTCs are output	B

HINT:

If any DTCs and other than P0116 are output, troubleshoot those DTCs first.

GO TO DTC CHART

2.	INSPECT THERMOSTAT

(a) Inspect the thermostat (thermostat opening temperature).

Click here

HINT:

Perform "Inspection After Repair" after replacing the engine coolant temperature sensor.

Click here

REPLACE ENGINE COOLANT TEMPERATURE SENSOR

REPLACE THERMOSTAT

SEE MORE:

Room Temperature Sensor Circuit (B1411)

DESCRIPTION The cooler thermistor (room temperature sensor) is installed in the instrument panel to detect the cabin temperature which is used to control the heater and air conditioning system AUTO mode. The resistance of the cooler thermistor (room temperature sensor) changes in accordance with the

Power Source Mode does not Change to ON (IG)

DESCRIPTION If the power switch is pressed with the electrical key transmitter sub-assembly in the cabin, the certification ECU (smart key ECU assembly) receives a signal and changes the power source mode. Related Data List and Active Test Items Problem Symptom Data List and Active Test Pow

Lexus NX: Engine Coolant Temperature Circuit Range / Performance (P0116)

READ NEXT:

Engine Coolant Temperature / Intake Air Temperature Correlation (P011B)

Throttle Pedal Position Sensor / Switch "A" Circuit (P0120-P0123,P0220,P0222,P0223,P2135)

Insufficient Coolant Temperature for Closed Loop Fuel Control (P0125)

SEE MORE:

Room Temperature Sensor Circuit (B1411)

Power Source Mode does not Change to ON (IG)