P0115, P0117, P0118

DTC Code	DTC Name
P0115	Engine Coolant Temperature Circuit Malfunction
P0117	Engine Coolant Temperature Circuit Low Input
P0118	Engine Coolant Temperature Circuit High Input

DESCRIPTION

A thermistor, whose resistance value varies according to the ECT, is built into the Engine Coolant Temperature (ECT) sensor.

The structure of the sensor and its connection to the ECM are the same as those of the Intake Air Temperature (IAT) sensor.

Tech Tips

When DTC P0115, P0117 or P0118 is set, the ECM enters fail-safe mode. During fail-safe mode, the ECT is estimated to be 80°C (176°F) by the ECM. Fail-safe mode continues until a pass condition is detected.

DTC No.	DTC Detection Condition	Trouble Area
P0115	Open or short in Engine Coolant Temperature (ECT) sensor circuit for 0.5 seconds (1 trip detection logic)	Open or short in ECT sensor circuit ECT sensor ECM
P0117	Short in Engine Coolant Temperature (ECT) sensor circuit for 0.5 seconds (1 trip detection logic)	Short in ECT sensor circuit ECT sensor ECM
P0118	Open in Engine Coolant Temperature (ECT) sensor circuit for 0.5 seconds (1 trip detection logic)	Open in ECT sensor circuit ECT sensor ECM

Tech Tips

When any of these DTCs are set, check the ECT by entering the following menus: Powertrain / Engine and ECT / Data List / All Data / Coolant Temp.

Reference
Temperature Displayed	Malfunction
-40°C (-40°F)	Open circuit
140°C (284°F) or higher	Short circuit

MONITOR DESCRIPTION

The Engine Coolant Temperature (ECT) sensor is used to monitor the ECT. The ECT sensor has a thermistor with a resistance that varies according to 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. These 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.

Example:

If the sensor output voltage is more than 4.91 V for 0.5 seconds or more, the ECM determines that there is an open in the ECT sensor circuit, and sets DTC P0118. Conversely, if the voltage output is less than 0.14 V for 0.5 seconds or more, the ECM determines that there is a short in the sensor circuit, and sets DTC P0117.
If the malfunction is not repaired successfully, a DTC is set 0.5 seconds after the engine is next started.

WIRING DIAGRAM

INSPECTION PROCEDURE

Tech Tips

If other DTCs relating to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
Read freeze frame data using the intelligent tester. 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.

PROCEDURE

READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)

Connect the intelligent tester to the DLC3.
Turn the power switch on (IG).
Turn the tester ON.
Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Coolant Temp.

Read the value displayed on the tester.

Standard
Between 80°C and 97°C (176°F and 207°F) with warm engine.

Result
Temperature Displayed	Proceed to
-40°C (-40°F)	A
140°C (284°F) or higher	B
Between 80°C and 97°C (176°F and 207°F)	C

Tech Tips

If there is an open circuit, the intelligent tester indicates -40°C (-40°F).
If there is a short circuit, the intelligent tester indicates 140°C (284°F) or higher.

B

READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN SENSOR) Click here

C

CHECK FOR INTERMITTENT PROBLEMS Click here

A

READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN SENSOR)
1. Disconnect the E14 Engine Coolant Temperature (ECT) sensor connector.
2. Connect terminals 1 and 2 of the ECT sensor connector on the wire harness side.
3. Connect the intelligent tester to the DLC3.
4. Turn the power switch on (IG).
5. Turn the tester ON.
6. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Coolant Temp.
7. Read the value displayed on the tester.
  
  Standard
  
  140°C (284°F) or higher.
NG
READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN ECM) Click here

OK

CONFIRM GOOD CONNECTION TO SENSOR. IF OK, REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here
READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN ECM)
1. Disconnect the E14 ECT sensor connector.
2. Connect terminals THW and E2 of the E1 ECM connector.
  
  Tech Tips
  
  Before checking, do visual and contact pressure checks on the ECM connector.
3. Connect the intelligent tester to the DLC3.
4. Turn the power switch on (IG).
5. Turn the tester ON.
6. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Coolant Temp.
7. Read the value displayed on the tester.
  
  Standard
  
  140°C (284°F) or higher.
NG
CONFIRM GOOD CONNECTION TO ECM. IF OK, REPLACE ECM Click here

OK

REPAIR OR REPLACE HARNESS OR CONNECTOR
READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN SENSOR)
1. Disconnect the E14 ECT sensor connector.
2. Connect the intelligent tester to the DLC3.
3. Turn the power switch on (IG).
4. Turn the tester ON.
5. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Coolant Temp.
6. Read the value displayed on the tester.
  
  Standard
  
  -40°C (-40°F)
NG
READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN ECM) Click here

OK

REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here
READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN ECM)
1. Disconnect the E1 ECM connector.
2. Connect the intelligent tester to the DLC3.
3. Turn the power switch on (IG).
4. Turn the tester ON.
5. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Coolant Temp.
6. Read the value displayed on the tester.
  
  Standard
  
  -40°C (-40°F)
NG
REPLACE ECM Click here

OK

REPAIR OR REPLACE HARNESS OR CONNECTOR

SFI SYSTEM, Diagnostic DTC:P0115, P0117, P0118