P011B

DTC P011B

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptor
DTC P0111
- Engine Coolant Temperature (ECT) - Intake Air Temperature (IAT) Correlation




Diagnostic Fault Information






Typical Scan Tool Data






Circuit Description

The intake air temperature (IAT) sensor is a variable resistor that measures the temperature of the engine coolant. The powertrain control module (PCM) supplies 5 volts to the IAT signal circuit and supplies a ground to the low reference circuit. The PCM monitors the mutual performance of the IAT and the engine coolant temperature (ECT) signals. The PCM monitors the warm up and cool down behavior of the sensors, after a vehicle driven at operating temperature is shut down. If the PCM detects that the IAT is not with in a predetermined range of ECT after a long soak, or the IAT and ECT are not within a range of each other, as compared to a previous cold start, this DTC sets.


The following table illustrates the difference between temperature, resistance, and voltage:






Conditions for Running the DTC

* The ignition has been off continuously for at least 7 hours.
* The battery voltage is at least 10.5 volts.
* The engine coolant temperature is at least -10°C (14°F) at engine start up.
* The IAT sensor is at least -10°C (14°F) after engine start.
* The engine has been running for at least 35 seconds.
* DTC P011B runs once per ignition cycle when the above conditions are met.



Conditions for Setting the DTC

The difference between the ECT sensor and the IAT sensor is greater than 20°C (36°F) after engine start up.


Action Taken When the DTC Sets

DTC P011B is a Type B DTC.


Conditions for Clearing the MIL/DTC

DTC P011B is a Type B DTC.


Diagnostic Aids

* Test the IAT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor can result in a DTC or a driveability condition. Refer to Temperature Versus Resistance (Temperature Versus Resistance).
* If the vehicle has sat overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F).
* High resistance in the circuit of the ECT sensor could set a DTC.



Reference Information
Schematic Reference

Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference

* Powertrain Control Module Connector End Views (Powertrain Control Module Connector End Views)
* Engine Controls Connector End Views (Engine Controls Connector End Views)

Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information


Circuit/System Verification

1. Verify that the following DTCs are not set: P0110, P0112 and P0113.

• If any of the DTCs are set, refer to DTC P0110, P0112, or P0113 (P0110).

2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.



Circuit/System Testing

1. Leave the ignition OFF for at least 7 hours.
2. Ignition ON, verify that the IAT sensor parameter and the ECT sensor parameter are within 10°C (18°F) of the ambient air temperature.

• If greater than the specified value, test the signal circuit of the appropriate sensor for high resistance. If the circuit tests normal, test the operation of appropriate temperature sensor.

3. If all circuits and the sensor test normal, replace the PCM.



Component Testing

1. Ignition OFF, disconnect the harness connector at the temperature sensor.

Important: A thermometer can be used to test the sensor off the vehicle.


2. Test the IAT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the Temperature Versus Resistance (Temperature Versus Resistance) table and verify that the resistance is within 5 percent of the specification.

• If not within the specified range, replace the temperature sensor.




Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Engine Coolant Temperature Sensor Replacement (Service and Repair)
* Intake Air Temperature Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for engine control module replacement, setup, and programming