Lexus NX: Engine Coolant Temperature / Intake Air Temperature Correlation (P011B)

Lexus NX Service Manual / Engine & Hybrid System / 2ar-fxe (engine Control) / Sfi System / Engine Coolant Temperature / Intake Air Temperature Correlation (P011B)

DESCRIPTION

The engine has two temperature sensors, an engine coolant temperature sensor and an intake air temperature sensor, to detect temperature while the engine is operating. A thermistor, whose resistance value varies according to the temperature, is built into each sensor. When the temperature becomes low, the resistance of the thermistor increases. When the temperature becomes high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes. Based on these temperature signals output from the sensors, the ECM determines the fuel injection duration and the ignition timing to control the engine.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory
P011B	Engine Coolant Temperature / Intake Air Temperature Correlation	All of the following conditions are met (2 trip detection logic): The auxiliary battery voltage is 10.5 V or higher. 7 hours or more have elapsed since the engine stopped on the previous trip. 60 seconds or more after a cold engine start. Either of the following conditions is met: The minimum intake air temperature after the engine starts is -10°C (14°F) or higher. The engine coolant temperature before the engine starts is -10°C (14°F) or higher. The difference between the readings of the engine coolant temperature and intake air temperature is more than 25°C (45°F).	Intake air temperature sensor (mass air flow meter sub-assembly) Engine coolant temperature sensor ECM	Comes on	DTC stored

HINT:

Waiting is required to prevent the temperature of the engine from affecting the readings. If the engine has been operated recently, it is not possible to accurately compare the readings.

For diagnosis, in order to duplicate the detection conditions of the DTC, it is necessary to park the vehicle for 7 hours. Parking the vehicle for 7 hours ensures that the actual temperature of the engine coolant temperature and intake air temperature are very similar. When the vehicle has been parked for less than 7 hours, differences in the readings may exist, but this does not necessarily indicate a fault.

MONITOR DESCRIPTION

The ECM monitors the difference between the engine coolant temperature and the intake air temperature when the engine is started cold to accurately detect the engine temperature conditions. The monitor runs when the engine is started after 7 hours or more have elapsed since the engine was stopped (power switch turned off) on the previous trip. If the difference between the engine coolant temperature and the intake air temperature on a cold start exceeds 25°C (45°F), the ECM interprets this as a malfunction in the engine coolant temperature sensor circuit and intake air temperature sensor circuit, and stores this DTC.

MONITOR STRATEGY

Related DTCs	P011B: Engine coolant temperature/Intake air temperature sensor correlation
Required Sensors/Components (Main)	Engine coolant temperature sensor Intake air temperature sensor
Required Sensors/Components (Related)	-
Frequency of Operation	Once per driving cycle
Duration	-
MIL Operation	2 driving cycles
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored	None
All of the following conditions are met	-
After power switch on (IG) and engine not running time	Less than 20 seconds
Soak Time	7 hours or more
Auxiliary battery voltage	10.5 V or higher
Time after engine start	60 seconds or more
Either of the following conditions is met	(a) or (b)
(a) Minimum intake air temperature after engine start	-10°C (14°F) or higher
(b) Engine coolant temperature before engine start	-10°C (14°F) or higher
Mass air flow meter circuit fail (P0102, P0103)	Not detected
Engine coolant temperature sensor circuit fail (P0115, P0117, P0118, P0125)	Not detected
Intake air temperature sensor circuit fail (P0112, P0113)	Not detected
Soak timer fail (P2610)	Not detected

TYPICAL MALFUNCTION THRESHOLDS

Deviated engine coolant temperature and intake air temperature

Less than -25°C (-45°F), or more than 25°C (45°F)

CONFIRMATION DRIVING PATTERN

Connect the Techstream to the DLC3.
Turn the power switch on (IG) and turn the Techstream on [A].
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the power switch off.
With the engine stopped, leave the vehicle as is for 7.5 hours or more [B].
Turn the power switch on (IG) and turn the Techstream on.
Put the engine in inspection mode (maintenance mode).
Click here
Start the engine and wait 60 seconds or more [C].
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [D].
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: P011B.

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 [A] through [D] 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:

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 P011B)

(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 P011B is output	A
DTC P011B and other DTCs are output	B

HINT:

If any DTCs other than P011B are output, troubleshoot those DTCs first.

GO TO DTC CHART

2.	READ VALUE USING TECHSTREAM (INTAKE AIR)

(a) Leave the vehicle for 7 hours or more.

HINT:

It is necessary to leave the vehicle for 7 hours or more to create conditions similar to the DTC detection conditions.

(b) Connect the Techstream to the DLC3.

(d) Turn the Techstream on.

(e) Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Intake Air.

Powertrain > Engine and ECT > Data List

Tester Display
Intake Air

(f) Read the value displayed on the Techstream.

Standard:

Difference between the intake air temperature and the actual outside air temperature is within 10°C (18°F).

HINT:

Temperature readings on the outside temperature gauge of the vehicle (if equipped) are not suitable for comparing to the intake air temperature reading. The outside temperature gauge has a significant delay built in to prevent swings in the temperature display. Use an accurate thermometer to determine the outside air temperature.
Perform "Inspection After Repair" after replacing the mass air flow meter sub-assembly.
Click here

REPLACE MASS AIR FLOW METER SUB-ASSEMBLY

3.	READ VALUE USING TECHSTREAM (COOLANT TEMP)

(a) Connect the Techstream to the DLC3.

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

(d) Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Coolant Temp.

Powertrain > Engine and ECT > Data List

Tester Display
Coolant Temp

(e) Read the value displayed on the Techstream.

Standard:

The difference between the coolant temperature and the actual outside air temperature is within 10°C (18°F).

HINT:

If the result is not as specified, check that there are no heat sources such as a block heater in the engine compartment.
Perform "Inspection After Repair" after replacing the engine coolant temperature sensor.
Click here

REPLACE ECM

REPLACE ENGINE COOLANT TEMPERATURE SENSOR

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Lexus NX: Engine Coolant Temperature / Intake Air Temperature Correlation (P011B)

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