P112A
DTC P112A
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P112A
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Intake Air Temperature (IAT) Sensor 1-Fuel Temperature Sensor Correlation
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The fuel temperature sensor and intake air temperature (IAT) sensor 1 are variable resistors. The fuel temperature sensor is located in the fuel pump and the IAT Sensor 1 is part of the mass air flow intake air temperature (MAF/IAT) sensor assembly. The engine control module (ECM) supplies 5 V to the signal circuits, and a ground for each sensor's low reference circuit. The ECM monitors the and Fuel Temperature Sensor and IAT Sensor 1 circuits in order to calculate the temperature of the fuel and air. The ECM monitors the Fuel Temperature Sensor and IAT Sensor 1 signals for excessively high or low voltages, or for a voltage that is not in correlation with the other sensor's start up signal.
Conditions for Running the DTC
Condition 1
* Ignition has been OFF for 8 hours or more.
* The ambient temperature is warmer than -60°C (-76°F).
* The engine is running.
OR
Condition 2
* Ignition has been OFF for 8 hours or more.
* The ambient temperature is warmer than -60°C (-76°F).
* The engine is running.
* In the first 60 s of engine run time, the ECM determines the block heater is OFF.
AND
* In the first 10 minutes of engine run time, the vehicle speed as been at least 24 km/h (15 mph) for at least 5 minutes and the ECM determines there is no Sunload
This DTC runs once per key cycle when the conditions in 1 or 2 are met.
Conditions for Setting the DTC
Condition 1
The ECM determines the absolute temperature difference between the Fuel Temperature Sensor and the IAT Sensor 1 signals is more than 100°C (180°F) at start up.
OR
Condition 2
* The ECM determines the absolute temperature difference between the Fuel Temperature Sensor signal and the IAT Sensor 1 signal is more than 20°C (36°F), but less than or equal to 100°C (180°F) after 10 minutes of engine run time.
* The ECM determines the block heater if OFF.
* The ECM determines there is no sunload.
Action Taken When the DTC Sets
DTC P112A is a Type B DTC.
Conditions for Clearing the DTC
DTC P112A is a Type B DTC.
Diagnostic Aids
* Skewed temperature sensors may cause this DTC to set.
* The Fuel Temperature Sensor is located in the Fuel Pump.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
Description and Operation
Fuel System Description Fuel System Description
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
Note:
* Perform Step 1 of this verification procedure only if the ignition has been OFF for 8 hours or more.
* The vehicle sitting in direct sun light or having the block heater ON will skew the results.
1. Ignition ON, observe the following scan tool parameters. The readings should be within 20°C (36°F) of each other, and the ambiant air temperature.
* Fuel Temperature Sensor
* IAT Sensor 1 Sensor
2. Engine idling, verify the appropriate scan tool parameters' readings are within the specified range. The readings depend on the current ambient temperature and the vehicle operating conditions.
* -37 to +139°C (-35 to +282°F); Fuel Temperature Sensor
* -39 to +148°C (-38 to +298°F); IAT Sensor 1 Sensor
3. 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
Note:
You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
1. For testing of the Fuel Temperature Sensor, refer to: Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for DTC P0182 or P0183.
.
2. Ignition OFF, disconnect the harness connector at the mass air flow/intake air temperature sensor.
3. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 ohms between the low reference circuit terminal 1 or A 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 K20 ECM.
4. Ignition ON, verify the scan tool parameter of the temperature sensor is colder than -39°C (-38°F).
• If warmer than the specified range, test the signal circuit terminal 2 or B for a short to ground. If the circuit tests normal, replace the K20 ECM.
Note:
If a short to voltage is found on the sensor signal circuit, the 3A fuse in the jumper wire will open.
5. Install a 3A fused jumper wire between the signal circuit terminal 2 or B and ground. Verify the scan tool parameter is warmer than 148°C (298°F).
• If colder 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 K20 ECM.
6. If all circuits test normal, test or replace the temperature sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Mass Airflow Sensor with Intake Air Temperature Sensor Replacement Mass Airflow Sensor with Intake Air Temperature Sensor Replacement
* Control Module References Control Module References for ECM replacement, setup, and programming