P0545
DTC P0545 or P0546
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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 (EGT) sensors 1 and 2 are variable resistors that measure the temperature of the exhaust at the inlet and 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.
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 (Fuel Temperature Sensor) Temperature Versus Resistance (EGT Sensors) Temperature Versus Resistance (IAT Sensor 1) Temperature Versus Resistance (ECT Sensors) Temperature Versus Resistance (IAT Sensor 2).
* EGT sensors may fail while operating under extreme temperatures. Review the Freeze Frame Failure Records to verify the failure criteria.
* 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 to +999°C (-38 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 that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
Important: Perform the Repair Verification after performing the 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 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 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 A 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 -35°C (-31°F).
• If warmer 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 or replace 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 (Fuel Temperature Sensor) Temperature Versus Resistance (EGT Sensors) Temperature Versus Resistance (IAT Sensor 1) Temperature Versus Resistance (ECT Sensors) Temperature Versus Resistance (IAT Sensor 2).
Repair Instructions
* Exhaust Particulate Filter Cleaning (LMM DPF Regeneration Enable) Exhaust Particulate Filter Cleaning (LMM DPF Service Regeneration) for Regeneration Enable
* Exhaust Temperature Sensor Replacement - Position 1
* Engine Control Module Replacement
Repair Verification
Notice: Refer to Diesel Particulate Filter (DPF) Regeneration Enable Notice.
Certain engine control conditions can cause the DPF to overload with soot. It will be necessary to clean the DPF as instructed to remove the excess soot accumulation. To avoid the customer's return to the service department, perform the appropriate Exhaust Particulate Cleaning procedure that is specified in the provided link.