DTC P1114 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage. Buick Century 1999

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1999 🢒 Century 🢒 Engine 🢒 Engine Controls - 3.1L 🢒 DTC P1114 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage

Engine Controls Components
Cell 20: Engine Data Sensors-A/C Refrig Press, ECT, IAT, MAP and TP
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Engine Coolant Temperature (ECT) sensor is a thermistor mounted in the engine coolant stream. The PCM applies a voltage (about 5.0 volts) through a pull up resistor to the ECT signal circuit. When the engine coolant is cold, the sensor (thermistor) resistance is high therefore the PCM will measure 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 that is intermittently below the range of the ECT sensor, DTC P1114 will set.

Conditions for Running the DTC

Engine running.

Conditions for Setting the DTC

•	The ECT sensor is intermittently greater than 139°C (282°F)

•	The condition is present for at least 3 seconds.

Action Taken When the DTC Sets

The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.

Conditions for Clearing the MIL/DTC

•	The DTC becomes history when the conditions for setting the DTC are no longer present.

•	The history DTC clears after 40 malfunction free warm-up cycles.

•	The PCM receives a clear code command from the scan tool.

Diagnostic Aids

Check for the following conditions:

Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

•	Poor terminal connection.

Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Refer to Intermittents and Poor Connections Diagnosis , and Connector Repairs Wiring Systems.

•	Damaged harness.

Inspect the wiring harness for damage. If the harness appears to be OK, observe the sensor display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the sensor display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems.

•	Inspect the PCM and the engine grounds for clean and secure connections.

If the DTC is determined to be intermittent, reviewing the Fail Records can be useful in determining when the DTC was last set.

Step	Action	Value(s)	Yes	No
1	Was the Powertrain OBD System Check performed?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Select Diagnostic Troble Codes (DTCs) and note any other DTCs set. Is DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage also set?	--	Go to DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage	Go to Step 3
3	Test the ECT signal circuit between the ECT sensor connector and the PCM for an intermittent short to ground. If a problem is found, repair as necessary. Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals , and Connector Repairs . Was a problem found?	--	Go to Step 4	Go to Diagnostic Aids
4	Review and record scan tool Fail Records data. Clear DTCs. Operate vehicle within Fail Records conditions as noted. Using a scan tool, monitor Specific DTC info for DTC P1114. Does scan tool indicate DTC P1114 failed?	--	Go to Step 2	System OK