P011A
DTC P011A
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 Correlation
Diagnostic Fault Information
Typical Scan Tool Data
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 or ECT 2 is skewed. The internal clock of the ECM will record the amount of time the ignition is OFF. If the calibration ignition OFF time is met at start-up, the ECM will compare the temperature difference between the ECT and the ECT 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.
* The engine run time is greater than 2 seconds.
* The start-up IAT is greater than -30°C (-22°F).
* DTC P011A runs continuously within the enabling conditions.
Conditions for Setting the DTC
When the ECM detects a temperature difference between the ECT and the 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 greater than -8°C (+18°C), then compare those measurements to the Temperature vs Resistance table.
Circuit/System Verification
Caution: Under pressure, the temperature of the solution in the radiator can be considerably higher, without boiling. Removing the radiator cap while the engine is hot (pressure is high), will cause the solution to boil instantaneously, with explosive force. The solution will spew out over the engine, fenders, and the person removing the cap. Serious bodily injury may result. Flammable antifreeze, such as alcohol, is not recommended for use at any time. Flammable antifreeze could cause a serious fire.
1. If the ignition has been OFF for 10 hours or more, the ECT 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 parameters. Compare those sensor parameters to each other, and also to the ambient temperature. A compare between ambient temperature and the coolant temperature sensors will determine which ECT is skewed
2. A quick compare between the ECT and ECT sensor 2 can be made at any time to determine which sensor is skewed.
3. Inspect the cooling system surge tank for the proper engine coolant level
4. 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 Records data.
Circuit/System Testing
Important: If you are unable to determine which ECT sensor is skewed, you must perform Circuit/System Verification first.
1. Ignition OFF, disconnect the harness connector at the affected ECT sensor.
2. Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal B and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the control module.
3. Ignition ON, verify the scan tool ECT parameter is less than -39°C (-40°F).
• If greater than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the control module.
4. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool ECT parameter is greater than 149°C (300°F)
• 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 control module.
5. If all circuits test normal, test or replace the ECT sensor.
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.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
* Engine Coolant Temperature Sensor Replacement
* Control Module References for engine control module (ECM) replacement, setup, and programming Programming and Relearning