P1115

DTC P1115

Circuit Description

The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT signal circuit and supplies a ground to the low reference circuit. If the ECM detects an intermittent high ECT signal voltage, which is a low temperature indication, this DTC sets.

The following table illustrates the difference between temperature, resistance, and voltage:






DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage

Conditions for Running the DTC

* The engine run time is more than 120 seconds.

* This DTC runs continuously once the above condition is met.

Conditions for Setting the DTC

The ECM detects that the ECT is less than -38°C (-36°F) intermittently for a total of 4 seconds during a 45 second time period.

Action Taken When the DTC Sets

* The control module stores the DTC information into memory when the diagnostic runs and fails.

* The malfunction indicator lamp (MIL) will not illuminate.

* The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.

* The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC

* 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 non-emission related diagnostic.

* Clear the DTC with a scan tool.

Diagnostic Aids

* 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.

* If the vehicle has set overnight, the ECT sensor and the intake air temperature (IAT) sensor values should display within 3°C (5°F). Refer to Temperature Versus Resistance Temperature Versus Resistance.

* For an intermittent condition, refer to Intermittent Conditions Intermittent Conditions.