DTC P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage. Oldsmobile Intrigue 1999

For 1990-2009 cars only

Makes 🢒 Oldsmobile 🢒 1999 🢒 Intrigue 🢒 Body and Accessories 🢒 Wiring Systems 🢒 DTC P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage

Engine Controls Components
Engine Data Sensors
OBD II Symbol Description Notice

Circuit Description

The engine coolant temperature (ECT) sensor is a thermistor mounted in the engine coolant stream. The powertrain control module (PCM) applies a voltage of about 5.0 volts to the ECT sensor through a pull up resistor. When the engine coolant is cold, the sensor (thermistor) resistance is high and the PCM measures a high signal voltage. As the engine coolant warms, the sensor resistance becomes less and the ECT signal voltage measured at the PCM drops. With a fully warmed up engine, the ECT signal voltage should measure about 1.5 to 2.0 volts. If the PCM detects an ECT signal volage that is intermittently greater than the range of the ECT sensor, DTC P1115 is set.

Conditions for Running the DTC

The engine is running for longer than 15 seconds.

Conditions for Setting the DTC

The ECT sensor intermittently indicates a coolant temperature of more than 134°C (274°F).

Action Taken When the DTC Sets

The PCM stores the conditions which were present when the DTC set as Fail Records data only.

Conditions for Clearing the MIL/DTC

•	A history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction.

•	The DTC may be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

Diagnostic Aids

Inspect for the following conditions:

•	A faulty connection at the PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connections.

•	Inspect the wiring harness for damage. If the harness appears to be OK, observe the ECT display on a scan tool while moving the connectors and wiring harnesses related to the ECT sensor. A change in the ECT display indicates the location of the malfunction.

•	A skewed or mis-scaled ECT sensor. Refer to Temperature vs Resistance .

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

DTC P1115 - ECT Sensor Circuit Intermittent High Voltage

Step	Action	Value(s)	Yes	No
1	Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Use a scan tool in order to select DTC info, Last Test Fail and note any other DTCs set. Is DTC P0118 also set?	--	Go to DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage	Go to Step 3
3	Test for a faulty sensor ground circuit terminal connection at the engine coolant temperature (ECT) sensor. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 9	Go to Step 4
4	Inspect for a faulty ECT signal circuit terminal connection at the ECT sensor. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 9	Go to Step 5
5	Test the ECT signal circuit between the ECT sensor connector and the PCM for an intermittent open. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 9	Go to Step 6
6	Test the ECT signal circuit between the ECT sensor connector and the PCM for an intermittent short to voltage. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 9	Go to Step 7
7	Inspect for a faulty sensor ground circuit terminal connection at the PCM. If a problem is found, repair as necessary. Refer to Connector Repairs in Wiring Systems. Was a problem found?	--	Go to Step 9	Go to Step 8
8	Test for an intermittent open in the sensor ground circuit. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 9	Go to Diagnostic Aids
9	Review and record the scan tool Fail Records data. Clear the DTCs. Operate the vehicle within the Fail Records conditions as noted. Use the scan tool in order to monitor the Specific DTC info for DTC P1115. Does the scan tool indicate DTC P1115 failed?	--	Go to Step 2	System OK