Circuit Description
DTC P0116 inspects the accuracy of the engine coolant temperature (ECT) sensor signal. The ECT sensor is a thermistor. A thermistor is a resistor whose value varies with temperature. The ECT sensor resistance is high when the coolant temperature is cold, and the ECT sensor resistance is low when the coolant temperature is warm. The engine control module (ECM) applies a 5-volt to the ECT sensor. The ECM monitors the voltage across the ECT sensor and converts the voltage into a temperature reading. The ECM will receive a high voltage input when the coolant temperature is cold. The ECM will receive a low voltage input when the coolant temperature is warm. A DTC P0116 may set if the ECT sensor voltage does not indicate that the engine coolant temperature has increased sufficiently during engine operation.
Conditions for Setting the DTC
| • | The coolant temperature is higher than 85°C (185°F). |
| • | The difference between modeled ECT and the starting ECT is higher than expected while the difference between the ECT signal and the starting ECT is less than expected. |
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate. |
| • | The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers. |
| • | A history DTC is stored. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF at the end of 3 consecutive validation cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 warm-up cycles without a fault. |
| • | DTCs can be cleared by using the scan tool. |
Diagnostic Aids
Inspect for any of the following conditions:
| • | Inspect for the proper operation of the engine cooling system, including the correct coolant level. |
| • | A faulty thermostat that stays open slightly can cause a DTC P0116 to set in cold weather when the vehicle is started and let sit while warming up. |
| • | Inspect for a faulty electrical connection to the ECM. |
An intermittent condition may be caused by a fault in the ECT sensor electrical circuit. Inspect the wiring harness and components for an intermittent condition.
Repair any electrical circuit faults that were found. If a DTC P0116 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC was first set.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Perform the Diagnostic System Check-Engine Controls. Is the system check complete? | -- | Go to Step 2 | |||||||||
2 | Check for DTC P0117 or DTC P0118 with a scan tool. Is DTC P0117 or P0118 present? | -- | Go to Step 3 | |||||||||
3 |
Is the ECT sensor value near the actual coolant temperature? | -- | Go to Step 11 | Go to Step 4 | ||||||||
4 |
Is the ECT below the specified value? | -30°C (-22°F) | Go to Step 5 | Go to Step 8 | ||||||||
5 |
Is the ECT above the specified value? | 180°C (356°F) | Go to Step 13 | Go to Step 6 | ||||||||
6 |
Is the ECT above the specified value? | 180°C (356°F) | Go to Step 7 | Go to Step 8 | ||||||||
7 | Repair the open or electrical resistance in the ECT sensor ground circuit. Is the repair complete? | -- | Go to Step 14 | Go to Step 9 | ||||||||
8 |
Was a repair necessary? | -- | Go to Step 14 | Go to Step 9 | ||||||||
9 |
Was a repair necessary? | -- | Go to Step 14 | Go to Step 10 | ||||||||
10 | Replace the ECM. Refer to Engine Control Module Replacement . Is the replacement complete? | -- | Go to Step 14 | -- | ||||||||
11 |
Was a repair necessary? | -- | Go to Step 14 | Go to Step 12 | ||||||||
12 |
Does DTC P0116 set? | -- | Go to Step 13 | Go to Diagnostic Aids | ||||||||
13 | Replace the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement . Is the replacement complete? | -- | Go to Step 14 | -- | ||||||||
14 |
Does the DTC run and pass? | -- | Go to Step 15 | Go to Step 2 | ||||||||
15 | With a scan tool, observe the stored information. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |
