P0118
DTC P0118: Engine Coolant Temperature Circuit High InputEnging Coolant Temperature Sensor Circuit:
CIRCUIT OPERATION
- 5-volt voltage is applied to the engine coolant temperature sensor output terminal (terminal No.1) from the ECM (terminal No.44) via the resistor in the ECM. The ground terminal (terminal No.2) is grounded with ECM (terminal No.49).
- The engine coolant temperature sensor is a negative temperature coefficient type of resistor. It has the characteristic that when the engine coolant temperature rises the resistance decreases.
- The engine coolant temperature sensor output voltage increases when the resistance increases and decreases when the resistance decreases.
TECHNICAL DESCRIPTION
- The engine coolant temperature sensor converts the engine coolant temperature to a voltage and outputs it.
- The ECM checks whether this voltage is within a specified range.
DESCRIPTIONS OF MONITOR METHODS
- Engine coolant temperature sensor output voltage is out of specified range.
MONITOR EXECUTION
- Continuous
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Not applicable
Sensor (The sensor below is determined to be normal)
- Not applicable
DTC SET CONDITIONS
Logic Flow Chart:
Logic Flow Chart
Check Condition
- 2 seconds or more have passed since the engine staring sequence was completed.
Judgment Criterion
- Engine coolant temperature sensor output voltage has continued to be 4.6 volts or higher [corresponding to a coolant temperature of -45 degree C (-49 degree F) or lower] for 2 seconds.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function-OBD-II Drive Cycle - Pattern 23. OBD-II Drive Cycle Pattern Lists
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Engine coolant temperature sensor failed.
- Open or shorted engine coolant temperature sensor circuit, or connector damage.
- ECM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
STEP 1. Using scan tool MB991958, check data list item 21: Engine Coolant Temperature Sensor.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to the data reading mode for item 21, Engine Coolant Temperature Sensor.
- The engine coolant temperature and temperature shown with the scan tool should approximately match.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES: It can be assumed that this malfunction is intermittent.
NO: Go to Step 2.
STEP 2. Check harness connector B-107 at the engine coolant temperature sensor for damage.
Q: Is the harness connector in good condition?
YES: Go to Step 3.
NO: Repair or replace it. Then go to Step 11.
STEP 3. Measure the sensor supply voltage at engine coolant temperature sensor harness side connector B-107.
1. Disconnect connector B-107 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No.1 and ground.
- Voltage should be between 4.5 and 4.9 volts.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.5 and 4.9 volts?
YES: Go to Step 7.
NO: Go to Step 4.
STEP 4. Measure the sensor supply voltage at ECM connector C-119 by backprobing.
1. Do not disconnect the ECM connector C-119.
2. Disconnect the engine coolant temperature sensor connector B-107.
3. Turn the ignition switch to the "ON" position.
4. Measure the voltage between terminal No.44 and ground by backprobing.
- Voltage should be between 4.5 and 4.9 volts.
5. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.5 and 4.9 volts?
YES: Go to Step 5.
NO: Go to Step 6.
STEP 5. Check harness connector C-119 at ECM for damage.
Q: Is the harness connector in good condition?
YES: Repair harness wire between engine coolant temperature sensor connector B-107 and ECM connector C-119 because of open circuit. Then go to Step 11.
NO: Repair or replace it. Then go to Step 11.
STEP 6. Check harness connector C-119 at ECM for damage.
Q: Is the harness connector in good condition?
YES: Replace the ECM. Then go to Step 11.
NO: Repair or replace it. Then go to Step 11.
STEP 7. Check for continuity at engine coolant temperature sensor harness side connector B-107.
1. Disconnect connector B-107 and measure at the harness side.
2. Check for the continuity between terminal No.2 and ground.
- Should be less than 2 Ohms.
Q: Does continuity exist?
YES: Go to Step 10.
NO: Go to Step 8.
STEP 8. Check harness connector C-119 at ECM for damage.
Q: Is the harness connector in good condition?
YES: Go to Step 9.
NO: Repair or replace it. Then go to Step 11.
STEP 9. Check for open circuit between engine coolant sensor connector B-107 (terminal No.2) and ECM connector C-119 (terminal No.49).
Q: Is the harness wire in good condition?
YES: Replace the ECM. Then go to Step 11.
NO: Repair it. Then go to Step 11.
STEP 10. Check the engine coolant temperature sensor.
1. Disconnect the engine coolant temperature sensor connector B-107.
2. Remove the engine coolant temperature sensor.
3. With the temperature sensing portion of engine coolant temperature sensor immersed in hot water, check resistance.
Standard value:
14 - 17 kOhms [at -20 degree C (-4 degree F)]
5.1 - 6.5 kOhms [at 0 degree C (32 degrees F)]
2.1 - 2.7 kOhms [at 20 degrees C (68 degrees F)]
0.9 - 1.3 kOhms [at 40 degrees C (104 degrees F)]
0.48 - 0.68 kOhm [at 60 degrees C (140 degrees F)]
0.26 - 0.36 kOhm [at 80 degrees C (176 degrees F)]
4. Apply 3M(TM) AAD part number 8731 or equivalent on the screw section of the engine coolant temperature sensor.
5. Install the engine coolant temperature sensor, and tighten to the specified torque.
Tightening torque: 29 ± 10 N.m (22 ± 6 ft-lb)
Q: Is the measured resistance at the standard value?
YES: Replace the ECM. Then go to Step 11.
NO: Replace the engine coolant temperature sensor. Then go to Step 11.
STEP 11. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to, Diagnostic Function - OBD-II Drive Cycle - Pattern 23. OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0118 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.