Diagnostic Instructions

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

Circuit	Short to Ground	Open	High Resistance	Short to Voltage	Signal Performance
Exhaust Gas Temperature Sensor 1 Signal	P0545	P0546	P20E2	P0546	P20E2
Exhaust Gas Temperature Sensor 1 Low Reference	--	P0546	P20E2	P0546	P20E2

Typical Scan Tool Data

EGT Sensor 1

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Ignition ON Parameter Normal Range: -39 to +999°C (-38 to +1,830°F)
Exhaust Gas Temperature Sensor 1 Signal	-40°C (-40°F)	1 000°C (1,832°F)	1 000°C (1,832°F)
Exhaust Gas Temperature Sensor 1 Low Reference	--	1 000°C (1,832°F)	1 000°C (1,832°F)

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

Conditions for Setting the DTC

P0545

The ECM detects that the EGT sensor is less than 0.32 volts 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

Conditions for Clearing the DTC

DTCs P0545 and P0546 are Type A DTCs.

Diagnostic Aids

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Description and Operation

Diesel Particulate Filter (DPF) System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Special Tools

J 25070 Heat Gun 500-750°F

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 and scan tool disconnected 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

Important: You must perform the Circuit/System Testing in order to verify the integrity of the EGT sensor circuits before proceeding with the Component Testing.

To simulate a high temperature failure condition, heat the sensor with the J 25070 while measuring and recording the resistance. Compare those measurements to the Temperature Versus Resistance.

While monitoring the DMM, manipulate the sensor harness under varying temperature conditions to help duplicate an intermittent condition.

If a heat gun is unavailable, a high temperature condition may be achieved by test driving the vehicle at normal operating temperature while monitoring the scan tool EGT Sensor 1 and 2 parameters.

Repair Instructions

Repair Verification

1. Install any components or connectors that have been removed or replaced during diagnosis.
2. Perform any adjustment, programming, or setup procedures that are required when a component or module is removed or replaced.
3. Clear the DTCs.
4. Turn OFF the ignition for 90 seconds.
5. Duplicate the Conditions for Running the DTC and use the freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to the Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure.
6. Perform the Diesel Particulate Filter (DPF) Service Regeneration.