Troubleshooting
DTC P0115 Engine Coolant Temperature CircuitCIRCUIT DESCRIPTION
A thermistor is built into the engine coolant temperature 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 those of intake air temperature sensor.
DTC Detection Condition:
HINT: If the ECM detects the DTC P0115, P0117 or P0118, it operates the fail-safe function in which the engine coolant temperature is assumed to be 80 °C (176 °F).
HINT: After confirming DTC P0115, P0117 or P0118, confirm the engine coolant temperature in the "DIAGNOSIS/ENHANCED OBD II/DATA LIST/ALL" using the hand-held tester or the OBD II scan tool.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions:
Typical Malfunction Thresholds:
Component Operating Range:
The ECT (Engine Coolant Temperature) 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 resistance varies as output voltage from the sensor changes.
The ECM monitors the sensor voltage and uses this value to calculate the engine coolant temperature. 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:
When the ECM calculates that the ECT is less than -40 °C (-40 °F), or more than 140 °C (284 °F), and if either the condition continues for 0.5 sec. or more, the ECM will set a DTC.
Wiring Diagram:
Step 1:
Step 2:
Step 3:
Step 4:
Step 5:
INSPECTION PROCEDURE
HINT:
- If different DTCs related to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may be open.
- Read freeze frame data using the hand-held tester or the OBD II scan tool. 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, as well as other data from the time when a malfunction occurred.
CHECK FOR INTERMITTENT PROBLEMS
Hand-held tester only:
Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect when the ECM is in check mode with hand-held tester. In check mode, the ECM uses 1 trip detection logic, which has a higher sensitivity to malfunctions than normal mode (default), which uses 2 trip detection logic.
a. Clear the DTCs.
b. Set the check mode.
c. Perform a simulation test.
d. Check the connector and terminal.
e. Wiggle the harness and connector.