Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P011A: Engine Coolant Temperature (ECT) Sensor 1-2 CorrelationDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
ECT Sensor 1 Signal | P0117, P011A | P0118, P011A | P0118, P011A | P0116, P0128, P011A |
Low Reference | -- | P0118, P011A | P0118, P011A | P0128, P011A |
ECT Sensor 2 Signal | P2185 | P2184 | P2184 | P0116, P0128, P011A |
Low Reference | -- | P2184 | P2184 | P0128, P011A |
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Parameter Normal Range: -39 to +120°C (-38 to +248°F) | |||
ECT Sensor Signal | 149°C (302°F) | -40°C (-40°F) | -40°C (-40°F) |
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F) |
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Parameter Normal Range: -39 to +120°C (-38 to +248°F) | |||
ECT Sensor 2 Signal | 149°C (300°F) | -40°C (-40°F) | -40°C (-40°F) |
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F) |
Circuit/System 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 signal circuit and a ground for the low reference circuit. The ECM uses this rationality diagnostic to determine if the input from the ECT sensor 1 or ECT sensor 2 is skewed. The ECM will compare the temperature difference between the ECT sensor 1 and the ECT sensor 2 to determine if the temperatures are within an acceptable operating range of each other.
Conditions for Running the DTC
| • | DTCs P0117, P0118, P0128, P2184, P2105 are not set. |
| • | The ignition is ON. |
| • | DTC P011A runs continuously within the enabling conditions. |
Conditions for Setting the DTC
When the ECM detects a temperature difference between ECT sensor 1 and ECT sensor 2 of more than 5°C (41°F).
Action Taken When the DTC Sets
DTC P011A is a Type B DTC.
Conditions for Clearing the DTC
DTC P011A is a Type B DTC.
Diagnostic Aids
| • | Inspect the ECT sensor terminals for corrosion and for engine coolant leaking through the sensor. Engine coolant that is leaking through the sensor will create a high resistance short to ground. This condition results in less voltage on the ECT sensor signal circuit, which is interpreted by the ECM as a warmer ECT. |
| • | This diagnostic runs in a specific range. Measure and record the resistance of the ECT sensor at various ambient temperatures warmer than -8°C (+18°C), then compare those measurements to the Temperature vs Resistance table. Refer to Temperature Versus Resistance . |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
- Verify that the DTCs P0117, P0118, P2184 or P2185 are not set.
- If the ignition has been OFF for 10 hours or more, the ECT sensor 1 and the ECT sensor 2 should be within 5°C (41°F) of each other, and also the ambient temperature. Turn ON the ignition, with the engine OFF, and use a scan tool to observe the ECT sensor 2 and the ECT sensor 1 parameters. Compare those sensor parameters to each other, and to the ambient temperature. A comparison between ambient temperature and the coolant temperature sensors will determine which ECT is skewed.
- A quick comparison between ECT sensor 1 and ECT sensor 2 can be made at any time to determine which sensor is skewed.
- 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 data.
| ⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
Circuit/System Testing
Important: If you are unable to determine which ECT sensor is skewed, you must perform Circuit/System Verification first.
- Ignition OFF, disconnect the harness connector at the affected ECT sensor.
- Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal A and ground.
- Ignition ON, verify the scan tool ECT parameter is colder than -39°C (-40°F).
- Install a 3A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool ECT parameter is warmer than 149°C (300°F).
- If all circuits test normal, test or replace the ECT sensor.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the ECM. |
| ⇒ | If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Component Testing
Measure and record the resistance of the ECT sensor at various ambient temperatures and compare those measurements to the Temperature vs. Resistance table. Refer to Temperature Versus Resistance .
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
