Diagnostic Aids

WARNING: This page is about a different car, the 2004 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.

An ECT sensor or PCM which is intermittently shorted to ground or 5-volt reference, open, or skewed is possible yet very unlikely.
An intermittent open or short to voltage in the ECT sensor signal circuit could result in a DTC P1115.
Use the Temperature vs Resistance Value scale to test the coolant sensor at various temperature levels to evaluate the possibility of a skewed sensor. A skewed sensor could result in poor driveability conditions. Refer to Temperature vs Resistance .
If an intermittent condition is suspected, refer to Intermittent Conditions .

DTC P1115

Step	Action	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) Connector End Views
1	Did you perform the Diagnostic System Check-Engine Controls?	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	Observe the DTC information with a scan tool. Is DTC P0118 set?	Go to DTC P0118	Go to Step 3
3	Observe the engine coolant temperature (ECT) sensor temperature while moving the ECT sensor connector and the powertrain control module (PCM) connector. Refer to Inducing Intermittent Fault Conditions in Wiring Systems. Does the scan tool indicate an abrupt change in value?	Go to Step 6	Go to Step 4
4	Observe the ECT parameter with a scan tool while moving the wiring harness at the ECT sensor and the PCM. Refer to Inducing Intermittent Fault Conditions in Wiring Systems. Does the scan tool indicate an abrupt change in value?	Go to Step 7	Go to Step 5
5	Observe the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	Go to Step 2	System OK
6	Repair the connector or terminal as necessary. Refer to Circuit Testing and Connector Repairs in Wiring Systems. Did you complete the repair?	Go to Step 8	-
7	Repair the harness or wiring as necessary. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair?	Go to Step 8	-
8	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running in the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	Go to Step 2	Go to Step 9
9	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	Go to Diagnostic Trouble Code (DTC) List	System OK