Toyota Tundra. Manual — part 1531

MONITOR DESCRIPTION

Engine coolant temperature (ECT) sensor cold start monitor

When a cold engine start is performed and then the engine is warmed up, if the ECT 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 a DTC is stored.

ECT sensor soak monitor

If the ECT 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 a DTC is stored.

MONITOR STRATEGY

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

ECT sensor cold start monitor:

TYPICAL ENABLING CONDITIONS - ECT SENSOR COLD START MONITOR

sensor value does not
change.

Related DTCs

P0116: Engine coolant temperature (ECT) sensor cold start
monitor
P0116: ECT sensor soak monitor

Required Sensors/Components (Main) ECT sensor
Required Sensors/Components
(Related)

None

Frequency of Operation

Once per driving cycle

Duration

10 seconds or more

MIL Operation

2 driving cycles

Sequence of Operation

None

Monitor runs whenever following DTCs not present

P0112, P0113 (Intake Air Temperature Sensor)

Battery voltage

10.5 V or more

Time after engine start

1 second or more

ECT at engine start

Less than 60°C (140°F)

Soak time

0 seconds or more

Accumulated MAF

1963 g or more

Fuel cut

OFF

Difference between ECT at engine start and IAT

Less than 40°C (72°F)

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra

ECT sensor soak monitor:

TYPICAL ENABLING CONDITIONS - ECT SENSOR SOAK MONITOR

TYPICAL MALFUNCTION THRESHOLDS

ECT sensor cold start monitor:

TYPICAL MALFUNCTION THRESHOLDS - ECT SENSOR COLD START MONITOR

ECT sensor soak monitor:

TYPICAL MALFUNCTION THRESHOLDS - ECT SENSOR SOAK MONITOR

COMPONENT OPERATING RANGE

COMPONENT OPERATING RANGE

INSPECTION PROCEDURE

HINT:



If any of DTCs P0115, P0117, P0118 or P0125 are set simultaneously with DTC P0116, the ECT sensor
may have an open or a short circuit. Troubleshoot those DTCs first.



Read freeze frame data using the Techstream. Freeze frame data records the engine condition when
malfunctions are detected. 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.

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

a. Connect the Techstream to the DLC3.

b. Turn the ignition switch to ON.

c. Turn the Techstream ON.

Monitor runs whenever following DTCs not present

P0102 - P0103: MAF meter

Battery voltage

10.5 V or more

Engine

Running

Soak time

5 hours or more

Either (a) or (b) condition met

-

(a) ECT

60°C (140°F) or more

(b) Accumulated MAF

3931 g or more

ECT sensor value change

Less than 5°C (9°F)

Difference between current ECT sensor value and previous ECT
sensor value when engine stopped

Less than 5°C (9°F) [varies with ECT
of last trip engine stop]

ECT

ECT sensor value changes in accordance with actual ECT

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra

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

e. Read the DTC.

Result

RESULT REFERENCE

B: GO TO DTC CHART

A: Go to next step.

2. INSPECT THERMOSTAT

a. Remove the thermostat (see REMOVAL ).

b. Measure the valve opening temperature of the thermostat.

Standard opening temperature: 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.

c. Reinstall the thermostat (see INSPECTION ).

NG: REPLACE THERMOSTAT (See REMOVAL )

OK: REPLACE ENGINE COOLANT TEMPERATURE SENSOR (See REMOVAL )

DTC P011B ENGINE COOLANT TEMPERATURE/INTAKE AIR TEMPERATURE CORRELATION

DESCRIPTION

The engine has two temperature sensors, an Engine Coolant Temperature (ECT) sensor and an Intake Air
Temperature (IAT) sensor, to detect the temperature while the engine is in operation. A thermistor, whose
resistance value varies according to the temperature, is built into each sensor. When the temperature is low, the
resistance of the thermistor increases. When the temperature is 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 time and the ignition timing to control the engine.

DTC DETECTION CONDITION AND TROUBLE AREA REFERENCE CHART

Result

Proceed to

P0116 is output

A

P0116 and other DTCs are output

B

DTC

DTC Detection Condition

Trouble Area

All of the following conditions are

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra

Fig. 84: Voltage Graph Between ECT And IAT Sensor
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

HINT:



Waiting is required to prevent the temperature of the engine from affecting the readings. If the engine has
been operated recently, it will not be 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 ECT and IAT are
very similar. When the vehicle has been parked for less than 7 hours, differences in the readings may
exist, this does not necessarily indicate a fault.

MONITOR DESCRIPTION

The ECM monitors the difference between the Engine Coolant Temperature (ECT) and the Intake Air
Temperature (IAT) when the engine is started cold to detect the engine temperature conditions accurately. The

P011B

met (2 trip detection logic):

a. The battery voltage is 10.5 V

or higher.

b. 7 hours or more have elapsed

from engine stop on the
previous trip.

c. 15 seconds after a cold

engine start.

d. The minimum Intake Air

Temperature (IAT) after the
engine starts is higher than -
10°C (14°F).

e. The average Engine Coolant

Temperature (ECT) before
the engine starts is higher
than -10°C (14°F).

f. The difference between the

readings of ECT and IAT is
higher than 20°C (36°F).



IAT sensor



ECT sensor



ECM

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra