DTC P0117 Without RPO CTF
Circuit Description
The engine coolant temperature (ECT) sensor is a variable resistor, sometimes called a thermistor, that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT signal circuit . When the ECT is cold, the sensor resistance is high. When the ECT increases, the sensor resistance lowers. With high sensor resistance, the ECM detects a high voltage on the ECT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the ECT signal circuit. If the ECM detects an excessively low ECT signal voltage, which is a high temperature indication, this DTC will set.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The ECT sensor temperature is more than 110°C (230°F) for more than 1 seconds.
Action Taken When the DTC Sets
The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
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. |
| • | 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 ECT should rise steadily to about 80°C (176°F) then stabilize when the thermostat opens. |
| • | Use the Temperature vs. Resistance value table in order to test the ECT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor could result in poor driveability concerns. Refer to Temperature Versus Resistance . |
| • | If the condition is suspected of being an intermittent, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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If this DTC can only be repeated by duplicating the Failure Records, refer to Temperature vs Resistance. The table may be used to test the ECT sensor at various temperatures in order to evaluate the possibility of a shifted sensor that may be shorted above or below a certain temperature. If this is the case, replace the ECT sensor. If the ECT sensor appears to be OK, the malfunction is intermittent: refer to Diagnostic Aids.
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When testing ECT signal circuit for a short to ground, you may need to inspect for continuity between all other ECM circuits.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 |
Does the scan tool indicate that the ECT sensor temperature is more than the specified value? | 138°C (280°F) | Go to Step 4 | Go to Step 3 |
Does the DTC reset? | -- | Go to Step 4 | Go to Diagnostic Aids | |
4 |
Does the scan tool indicate that the ECT sensor temperature is less than the specified value? | -38°C (-36°F) | Go to Step 6 | Go to Step 5 |
Did you find and correct the condition? | -- | Go to Step 8 | Go to Step 7 | |
6 | Replace the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement . Did you complete the replacement? | -- | Go to Step 8 | -- |
7 | Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data . Did you complete the replacement? | -- | Go to Step 8 | -- |
8 |
Does the DTC run and pass? | -- | Go to Step 9 | Go to Step 2 |
9 | With a scan tool observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
