P0116

P0116-ENGINE COOLANT TEMPERATURE SENSOR PERFORMANCE





For a complete wiring diagram Refer to Diagrams/Electrical.

Theory of Operation


The coolant temperature sensor is a variable resistor sensor and is used to measure the temperature of the coolant of the engine. The ECM supplies 5-volts to the coolant temperature signal circuit. The ECM monitors the change in voltage caused by changes in the resistance of the sensor to determine the coolant temperature. The engine coolant temperature sensor is located near the thermostat housing. 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 rationality check is referred to as a dither. The dither looks at the temperature reading from the sensor over time and ensures that it changes. This monitor is used to detect a "stuck" sensor. If the sensor reading does not change over a calibrated time limit, the fault will be recorded. Both the key-on and dither portions of this rationality error 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 an default value for the intake air temperature. 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 ECM does not read a change in value from the sensor over time.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview


Diagnostic Test


1. LOW COOLANT LEVEL
With the engine cold, verify the level of coolant in the radiator.
Is the radiator full of coolant?

Yes


- Go To2


No


- Fill the radiator with coolant- refer to the owners manual for assistance.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



2. COOLANT TEMPERATURE SENSOR
Remove the temperature sensor and reconnect the wiring to the sensor.
Turn the ignition on.
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 -15° C (5° F on the scan tool?

Yes


- Go To3


No


- Replace the coolant temp sensor.
- Perform 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 can result in personal injury or death.

Start the engine.
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 POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



4. COOLANT TEMPERATURE SENSOR
After an 8 hour cold soak, hook up scan tool and monitor inlet air temperature, battery temperature, intake air temperature and coolant temperature.

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


NOTE: Ensure 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 POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test


No


- Refer to the INTERMITTENT CONDITION - DIESEL Symptom. Intermittent Condition