P0546
DTC P0545 or P0546
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 provide an overview of each diagnostic category.
DTC Descriptors
DTC P0545
- Exhaust Temperature Sensor 1 (EGT-1) Circuit Low Voltage
DTC P0546
- Exhaust Temperature Sensor 1 (EGT-1) Circuit High Voltage
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The exhaust gas temperature sensors position 1 are variable resistors that measures the temperature of the exhaust at the inlet second outlet of the diesel particulate filter (DPF). The engine control module (ECM) supplies a bias 5-volt signal to the EGT signal circuit, and supplies a ground to the low reference circuit. When the EGT is cold, the sensor resistance is low. When the EGT temperature increases, the sensor resistance increases. With high sensor resistance, the ECM detects a higher voltage on the EGT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the EGT signal circuit.
Conditions for Running the DTC
* The ignition is ON.
* This DTC runs continuously when the above condition is met.
Conditions for Setting the DTC
P0545
* The ECM detects that the EGT sensor is less than 0.32 volt.
* The condition exists for greater than 1 second.
P0546
The ECM detects that the exhaust temperature sensor is greater than 3.37 volts for greater than 1 second.
Action Taken When the DTC Sets
* DTCs P0545 and P0546 are Type A DTCs.
* Normal regeneration will be inhibited.
Conditions for Clearing the DTC
DTCs P0545 and P0546 are Type A DTCs.
Diagnostic Aids
* Inspect the EGT sensor terminals for corrosion.
* Measure and record the resistance of the EGT sensor at various ambient temperatures greater than -8°C (+18°F), then compare those measurements to the Temperature Versus Resistance (Exhaust Gas Temperature Sensor) Temperature Versus Resistance (Fuel Temperature Sensor) Temperature Versus Resistance (IAT Sensor 1) Temperature Versus Resistance (ECT Sensors) Temperature Versus Resistance (IAT Sensor 2).
* A short to a separate 5-volt source occurs, this DTC will set.
Circuit/System Verification
1. Engine running, observe the scan tool EGT Sensor 1 parameter. The reading should be within the normal range -39°C to +999°C (-38°F to +1,830°F), depending on the current ambient temperature and the vehicle operating conditions.
2. Engine running, observe the DTC information with a scan tool. DTCs P0545 or P0546 should not set.
3. 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
1. Ignition OFF, disconnect the harness connector at the EGT sensor 1.
2. Ignition OFF, for 90 seconds. Test for less than 5 ohms of resistance 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 ECM.
3. Ignition ON, verify the scan tool EGT Sensor 1 parameter is greater than 998°C (1,828°F).
• If less than the specified range, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the ECM.
4. Install a 3A fused jumper wire between the signal circuit terminal A and a good ground. Verify the scan tool EGT parameter is less than -39°C (-38°F).
• If greater 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.
5. If all circuits test normal, test the sensor.
Component Testing
Measure and record the resistance of the EGT sensor 1 at various ambient temperatures and compare those measurements to the Temperature Versus Resistance (Exhaust Gas Temperature Sensor) Temperature Versus Resistance (Fuel Temperature Sensor) Temperature Versus Resistance (IAT Sensor 1) Temperature Versus Resistance (ECT Sensors) Temperature Versus Resistance (IAT Sensor 2).
Repair Instructions
Notice: After performing the system repair, perform the following:
* A code clear with a scan tool, regardless of whether or not a DTC is set
* A Diesel Particulate Filter (DPF) Regeneration Enable with a scan tool
Perform the above to avoid possible soot overloading conditions or possible damage to the DPF.
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
* Exhaust Particulate Filter Cleaning (DPF Service Regeneration) Exhaust Particulate Filter Cleaning (DPF Regeneration Enable) for Regeneration Enable
* Exhaust Temperature Sensor Replacement - Position 1
* Engine Control Module Replacement Verification Tests