P0115
Engine Coolant Temperature Sensor Circuit:
CIRCUIT OPERATION
- 5-volt voltage is applied to the engine coolant temperature sensor output terminal (terminal 1) from the ECM (terminal 44)
- 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 resistor decreases.
- The engine coolant temperature sensor output voltage increases when the resistor increases and decreases when the resistor decreases.
TECHNICAL DESCRIPTION
- The engine coolant temperature sensor converts the engine coolant temperature to a voltage and output it.
- The ECM
In addition, it checks that the engine coolant temperature (signal) does not drop while the engine is warming up.
DTC SET CONDITIONS
Check Conditions
- Two seconds or more have passed since the staring sequence was completed.
Judgement Criteria
- Engine coolant temperature sensor output voltage has continued to be 4.6 volts or higher [corresponding to a coolant temperature of -45°C (-49°F) or lower] for 2 seconds.
or
- Engine coolant temperature sensor output voltage has continued to be 0.1 volt or lower [corresponding to a coolant temperature of 140°C (284°F) or higher] for 2 seconds.
Check Conditions, Judgement Criteria
- Engine coolant temperature sensor output voltage increased from a value lower than 1.6 volts to a value higher than 1.6 volts [coolant temperature decreases from a higher than 40°C (104°F) temperature to a lower than 40°C (104°F) temperature].
- Then the engine coolant temperature sensor output voltage has continued to be 1.6 volts or higher for five minutes.
Check Conditions, Judgement Criteria
- About 60 - 300 seconds have passed for the engine coolant temperature to rise to about 10°C (50°F) after starting sequence was completed.
- However, time is not counted when fuel is shut off.
Check Conditions
- Engine coolant temperature was 7°C (44.6°F) or more immediately before the engine was stopped at the last drive.
- Engine coolant temperature was 7°C (44.6°F) or more when the engine started.
Judgement Criteria
- Engine coolant temperature fluctuates within 1°C (33.8°F) after five minutes have passed since the engine was started.
- However, time is not counted if any of the following conditions are met.
1. Intake air temperature is 60°C (140°F) or more.
2. Volume air flow sensor output frequency is 70 Hz or less.
3. During fuel shut-off operation.
- Only one monitor during one drive cycle
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 loose connector.
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tools:
MB991502: Scan Tool (MUT-II)
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
STEP 1. Using scan tool MB991502, check data list item 21: Engine Coolant Temperature Sensor.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to "ON" position.
3. Set scan tool MB991502 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.
If they match, this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope With Intermittent Malfunction.
If they don't match, go to Step 2.
STEP 2. Check the engine coolant temperature sensor.
1. Disconnect engine coolant temperature sensor connector B-11.
2. Measure the continuity between engine coolant temperature sensor side connector terminals 1 and 2.
- There should be continuity. (50 - 72 kohms)
If continuity, go to Step 3.
If no continuity, replace the engine coolant temperature sensor. Then go to Step 8.
STEP 3. Check the circuit at engine coolant temperature sensor connector B-11.
1. Disconnect connector B-11 and measure at the harness side.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 1 and ground.
- Voltage should be between 4.5 and 4.9 volts.
4. Turn the ignition switch to "LOCK" (OFF) position.
5. Check for the continuity between terminal 2 and ground.
- Should be less than 2 ohms .
If all checks above meet the specifications, go to Step 4.
If any check above does not meet the specifications, go to Step 5.
STEP 4. Check harness connector B-11 at engine coolant temperature sensor for damage.
If harness connector B-11 is in good condition, replace the engine coolant temperature sensor. Then go to Step 8.
If harness connector B-11 is damaged, repair or replace it.Refer to Harness Connector Inspection. Then go to Step 8.
STEP 5. Check harness connector C-58 at the ECM
If harness connector C-58
If harness connector C-58
STEP 6. Check the harness wire between engine coolant temperature sensor connector B-11 and ECM connector C-58
If the wire between engine coolant temperature sensor connector B-11 and ECM connector C-58
If the wire between engine coolant temperature sensor connector B-11 and ECM connector C-58
STEP 7. Check the engine coolant temperature sensor.
1. Disconnect engine coolant temperature sensor connector B-11.
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:
5.1 - 6.5 kohms [at 0°C (32°F)]
2.1 - 2.7 kohms [at 20°C (68°F)]
0.9 - 1.3 kohms [at 40°C (68°F)]
0.26 - 0.36 kohms [at 80°C (176°F)]
If within specifications, replace the ECM or PCM. Then go to Step 8.
NOTE: If not within specifications, replace the engine coolant temperature sensor Then go to Step 8.
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 Nm (22 ± 7 ft.lb)
STEP 8. Test the OBD-II drive cycle
1. Carry out a test drive with the drive cycle pattern. Refer to Procedure 6 - Other Monitor.
2. Read the diagnostic trouble code, and confirm that diagnostic trouble code P0115 does not reset.