[Previous][Next]
DTC P0116: Engine Coolant Temperature Circuit Range/Performance Problem
 
 
 
 
CIRCUIT OPERATION
  • 5-volt voltage is applied to the engine coolant temperature sensor output terminal from the ECM terminal WTS via the resistor in the ECM. The ground terminal is grounded with ECM terminal WTSE.
  • 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 resistor 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 does not change for specified period when engine coolant temperature sensor output voltage at engine start is over 7°C (45°F).
 
 
MONITOR EXECUTION
  • Once per driving cycle
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC set in memory for the item monitored below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Mass airflow sensor
  • Intake air temperature sensor
 
 
DTC SET CONDITIONS
Logic Flow Chart
 
 
Check Conditions
  • Engine coolant temperature was more than 7°C (45°F) when the engine started.
  • The accumulation is more than 300 seconds during the acceleration having the mass airflow rate of 12 g/sec or more.
  • The accumulation is more than 30 seconds during the deceleration having the mass airflow rate of 9 g/sec or less.
Judgment Criterion
  • Engine coolant temperature fluctuates within 1°C (1.8°F) after 330 seconds 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. During fuel shut-off operation.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Control as if the engine coolant temperature is 80°C (176°F).
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 9 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Engine coolant temperature sensor failed.
  • ECM failed.

 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle Communication Interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite Main Harness A
  • MB992747: V.C.I.-Lite USB Cable Short
  • MB992748: V.C.I.-Lite USB Cable Long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Using scan tool (M.U.T.-III), check data list item 6: Engine Coolant Temperature Sensor.
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T.-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(2) Turn the ignition switch to the "ON" position.
(3) Set scan tool (M.U.T.-III) to the data reading mode for item 6, 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.
Is the sensor operating properly?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
Go to Step 2.
 
STEP 2. Check the engine coolant temperature sensor.
Refer to Engine Coolant Temperature Sensor Check .
Is the engine coolant temperature sensor normal?
Go to Step 3.
Replace the engine coolant temperature sensor. Then go to Step 7.
 
STEP 3. Check the continuity at engine coolant temperature sensor harness side connector.
(1) Disconnect the engine coolant temperature sensor connector and measure at the harness side.
(2) Check for the continuity between terminal WTSE line and ground.
  • Continuity (2 ohms or less)
Does continuity exist?
Go to Step 5.
Go to Step 4.
 
STEP 4. Check of harness damage in WTSE line between engine coolant temperature sensor connector and ECM connector.
Is the harness wire in good condition?
Go to Step 6.
Repair the connector(s) or wiring harness. Then go to Step 7.
 
STEP 5. Check of harness damage in WTS line between engine coolant temperature sensor connector and ECM connector.
Is the harness wire in good condition?
Go to Step 6.
Repair the connector(s) or wiring harness. Then go to Step 7.
 
STEP 6. Using scan tool (M.U.T.-III), check data list item 6: Engine Coolant Temperature Sensor.
(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool (M.U.T.-III) to the data reading mode for item 6, Engine Coolant Temperature Sensor.
  • The engine coolant temperature and temperature shown with the scan tool should approximately match.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the sensor operating properly?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
Replace the ECM (Refer to, Removal and Installation ). Then go to Step 7.
 
STEP 7. 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 9 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P0116 set?
Retry the troubleshooting.
The inspection is complete.