P008F
DTC P008F
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 P008F
-
Engine Coolant Temperature (ECT) Fuel Temperature Not Plausible
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 V to the ECT sensor signal circuit and supplies a ground to the low reference circuit.
The ECM uses this rationality diagnostic to determine if the input from the ECT sensor or fuel temperature sensor is skewed. The ECM will compare the temperature difference between the ECT sensor and fuel temperature sensor to determine if the temperatures are within an acceptable operating range of each other.
Conditions for Running the DTC
DTC P0016, P0112, P0113, P0117, P0118, P0182, P0183, P0335, P0336, P0340 or P0341 is not set.
Condition 1
* Ignition has been OFF for 8 hours or more.
* The ambient temperature is greater 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 greater 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.
DTC P008F will only run once per ignition cycle until a Pass, Fail or Disable condition exists.
Conditions for Setting the DTC
Condition 1
The ECM determines the absolute temperature difference between the ECT sensor and fuel temperature sensor is more than 100°C (180°F) at engine start.
OR
Condition 2
* The ECM determines the absolute temperature difference between the ECT sensor and fuel temperature sensor is more than 20°C (36°F), but less than or equal to 100°C (180°F) after 60 seconds of engine run time.
* Block heater is not detected.
Action Taken When the DTC Sets
DTC P008F is a Type B DTC.
Conditions for Clearing the DTC
DTC P008F is a Type B DTC.
Diagnostic Aids
* Inspect the ECT sensor terminals and the ECT harness connector for corrosion. This condition results in a greater voltage on the ECT sensor signal circuit, which is interpreted by the ECM as a colder ECT.
* This diagnostic runs in a specific range. Measure and record the resistance of the ECT sensor at various ambient temperatures between -7 to +80°C (+19 to +176°F), then compare those measurements to the Temperature Versus Resistance (Fuel Temperature Sensor) Temperature Versus Resistance (Fuel Temperature Sensor)Temperature Versus Resistance (IAT Sensor 1) Temperature Versus Resistance (IAT Sensor 1)Temperature Versus Resistance (EGT Sensors) Temperature Versus Resistance (EGT Sensors)Temperature Versus Resistance (IAT Sensor 2) Temperature Versus Resistance (IAT Sensor 2)Temperature Versus Resistance (ECT Sensors) Temperature Versus Resistance (ECT Sensors)Temperature Versus Resistance (EGR Temperature Sensors) Temperature Versus Resistance (EGR Temperature Sensors) table.
* A slight to moderate resistance in the ECT sensor signal circuit or low reference circuit will affect this diagnostic. This condition results in a greater voltage on the ECT sensor signal circuit, which is interpreted by the ECM as a colder ECT.
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)
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
1. Ignition OFF, inspect the cooling system surge tank for the proper coolant level. Refer to Cooling System Leak Testing Component Tests and General Diagnostics and Cooling System Draining and Filling (Static Fill) Cooling System Draining and Filling (Static Fill)Cooling System Draining and Filling (Vac N Fill) Cooling System Draining and Filling (Vac N Fill)Cooling System Draining and Filling (Static Fill Diesel) Cooling System Draining and Filling (Static Fill).
2. Ignition OFF for 8 hours or greater.
3. Ignition ON, observe the scan tool Fuel Temperature Sensor and ECT Sensor parameters. The ECT and Fuel Temperature Sensor should be within 20°C (36°F) of each other.
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/Failure Records data.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the ECT sensor.
2. 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 5.0 ohms between the low reference circuit terminal 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.
3. Ignition ON, verify the scan tool ECT parameter is colder than -39°C (-40°F).
• If greater than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
4. Install a 3 A 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 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 K20 ECM.
5. If all circuits test normal, test or replace the B34 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. Refer to Temperature Versus Resistance (Fuel Temperature Sensor) Temperature Versus Resistance (Fuel Temperature Sensor)Temperature Versus Resistance (IAT Sensor 1) Temperature Versus Resistance (IAT Sensor 1)Temperature Versus Resistance (EGT Sensors) Temperature Versus Resistance (EGT Sensors)Temperature Versus Resistance (IAT Sensor 2) Temperature Versus Resistance (IAT Sensor 2)Temperature Versus Resistance (ECT Sensors) Temperature Versus Resistance (ECT Sensors)Temperature Versus Resistance (EGR Temperature Sensors) Temperature Versus Resistance (EGR Temperature Sensors).
* Refer to Thermostat Diagnosis Thermostat Diagnosis.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Engine Coolant Thermostat Replacement (V6)
* Engine Coolant Temperature Sensor Replacement Service and Repair
* Control Module References Control Module References for ECM replacement, setup, and programming