Circuit Description
The engine control module (ECM) monitors the temperature of the engine coolant for engine control and as an enabling criteria for some diagnostics. The amount of air flow into an engine is proportional to the amount of heat an engine generates. The ECM monitors the amount of air flow into the engine to calculate engine coolant temperature (ECT). The ECM uses the calculated temperature to determine if the engine has warmed up to the thermostat regulating temperature. If the coolant temperature does not increase normally, does not reach the regulating temperature of the thermostat, or goes over the thermostat regulating temperature, diagnostics that use the ECT as enabling criteria may not run when expected. If the engine coolant temperature is stuck in range above a certain threshold, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0217 Engine Coolant Over temperature
Conditions for Running the DTC
| • | DTCs P0117, P0118, P0122, P0123, P0502, P0562, P0563, P0606, P2610, and U0101 are not set. |
| • | The engine has been OFF for more than 6 hours |
| OR |
| The start-up engine coolant temperature (ECT) is less than 45°C (113°F). |
| • | The engine is running. |
| • | The ECT is more than 50°C (122°F). |
| • | The intake air temperature (IAT) is more than 35°C (95°F). |
| • | The airflow into the engine is less than 45 g/s or the calculated airflow into the engine is less than 43 g/s. If the ECM detects that the airflow into the engine is more than 45 g/s or 43 g/s after the diagnostic runs for 60 seconds, the ECM will not report a pass or fail. |
| • | This DTC runs once per ignition cycle once the above conditions are met. |
Conditions for Setting the DTC
The ECM detects that the engine coolant temperature is more than 107°C (225°F) for more than 2 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
| • | An overheating condition may cause this DTC to set. |
| • | After starting the engine, the engine coolant temperature should rise steadily, then stabilize after the thermostat opens. |
| • | Test the ECT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor can result in a driveability condition. Refer to Temperature Versus Resistance . |
| • | Check for the proper operation of the engine cooling system. |
| • | For an intermittent condition, refer to Symptoms - Engine Cooling . |
Test Description
The numbers below refer to the step numbers in the diagnostic table.
-
The cooling system could be causing this DTC to set. For example, restricted air flow through the radiator, low coolant level, or the incorrect type of coolant.
-
This step tests for excessive resistance in the ECT circuit.
-
This step isolates the condition. If the temperature changes, test for a condition in the low reference circuit. If the temperature remains the same, test the signal circuit for a condition.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |
2 |
Important: If DTC P0117 is also set, refer to DTC P0117 . Is the engine cooling system low on coolant? | -- | Go to Loss of Coolant | Go to Step 3 |
Is the customer's concern that the engine is operating at a higher temperature than normal or that the engine is overheating? | -- | Go to Step 4 | ||
4 |
Important: Return to this diagnostic procedure after you complete the thermostat diagnosis. Test for the correct operation of the thermostat. Refer to Thermostat Diagnosis . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 5 |
5 |
Important: Return to this diagnostic procedure after you complete the engine cooling fan diagnosis. Test for the correct operation of the engine cooling fans. Refer to Cooling Fan Circuit Diagnosis . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 6 |
Is the temperature more than the specified value? | 214°C (417°F) | Go to Step 10 | Go to Step 7 | |
Is the temperature more than the specified value? | 214°C (417°F) | Go to Step 8 | Go to Step 9 | |
8 | Test the low reference circuit of the ECT sensor for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 |
9 | Test the signal circuit of the ECT sensor for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 |
10 | Test for shorted terminals and poor connections at the ECT sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 12 |
11 | Test for shorted terminals and poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 13 |
12 | Replace the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- |
13 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- |
14 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 15 |
15 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
