P0116

P0116-ENGINE COOLANT TEMPERATURE SENSOR PERFORMANCE





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams. Electrical Diagrams

Theory of Operation

The Coolant Temperature Sensor is located near the thermostat housing and is used to measure the engine coolant temperature. The Coolant Temperature Sensor receives 5-volts and a sensor ground from the Engine Control Module (ECM). The ECM monitors the change in voltage to determine the coolant temperature. There are two parts to this fault code, a key on check and a rationality check. After an 8 hour cold soak, at key ON the readings for the inlet air temperature, battery temperature, intake air temperature and coolant temperature are all compared. If the temperatures differ more than a calibrated amount, then the appropriate sensor fault code would be recorded. The key on monitor is disabled for ambient temperatures below 20°F. This monitor looks for all the sensors to be grouped on one temperature or, in the case that the monitor fails, three sensors grouped at one temperature and one outlier. In the case that all four sensor values are distributed over a range of temperatures this diagnostic will not run. A block heater is one possible cause of such a distribution. The ECM rationality check looks at the temperature reading from the sensor over time and ensures that it changes with engine running. If the sensor reading does not change over a calibrated time limit, the fault will be recorded. Both the key-on and rationality portions of this monitor require that the diagnostic fails in two consecutive drive cycles before the MIL lamp is lit. The ETC lamp will also be illuminated. During this time the ECM uses a default value for the Coolant Temperature Sensor. The ECM turns off the MIL lamp when the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:
While the engine is running.

- Set Condition:
The Engine Control Module (ECM) does not read a change in value from the sensor over time.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. LOW COOLANT LEVEL
1. Turn the ignition off.
2. With the engine cold, verify the level of coolant in the cooling system.

Is the cooling system full of coolant?

Yes

- Go To 2

No

- Fill the cooling system to the proper level.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

2. COOLANT TEMPERATURE SENSOR
1. Remove the Coolant Temperature Sensor and reconnect the wiring to the sensor.
2. Turn the ignition on.
3. Monitor scan tool while heating the sensor with an external heat source (DO NOT USE OPEN FLAME).

Does the reading from the sensor increase at least (5°F) on the scan tool?

Yes

- Go To 3

No

- Replace the Coolant Temperature Sensor.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. THERMOSTAT

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

1. Start the engine.
2. Allow the engine to reach normal operating temperature.

Does the thermostat open properly at the correct temperature?

Yes

- Go To 4

No

- Replace the Thermostat.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

4. COOLANT TEMPERATURE SENSOR
1. Let vehicle cold soak for eight hours.
2. Turn the ignition on.
3. With a scan tool, monitor inlet air temperature, battery temperature, intake air temperature and coolant temperature.

NOTE: Make sure ambient air temperature is above 20°F when performing this test.

NOTE: Make sure there is no external heat source, such as a block heater, operating during this test or within the 8 hour cold soak.

Does the Coolant Temperature Sensor read differently from the other sensors?

Yes

- Replace the Coolant Temperature Sensor.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Refer to the INTERMITTENT CONDITION - DIESEL diagnostic procedure. Intermittent Condition Test.