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P0545






P0545-EXHAUST GAS TEMPERATURE SENSOR CIRCUIT LOW - BANK 1 SENSOR 1





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.

Theory of Operation

The aftertreatment temperature sensors are used by the Engine Control Module (ECM) to monitor the engine exhaust temperatures in the aftertreatment system. The aftertreatment temperature sensors are thermistors and change resistance based on the temperature being measured. The ECM provides a 5-volt reference voltage to the sensor. The ECM monitors the change in signal voltage and converts this to a temperature value. When the exhaust gas temperature is cold, the sensor or thermistor resistance is high. The ECM signal voltage only pulls down a small amount through the sensor to ground. Therefore, the ECM senses a high signal voltage or low temperature. When the exhaust gas temperature is hot, the sensor resistance is low. The signal voltage pulls down a large amount. Therefore, the ECM senses a low signal voltage, or a high temperature. The ECM will set the fault code if it detects that the aftertreatment Diesel Particulate Filter inlet Exhaust Gas Temperature Sensor Signal voltage is less than a calibrated voltage for longer than a calibrated period. The ECM illuminates the MIL lamp immediately when the diagnostic runs and fails. A default value for the aftertreatment diesel particulate filter inlet temperature reading will be used and active regeneration of the diesel particulate filter will be disabled. The ECM will turn off the MIL lamp immediately after the diagnostic runs and passes.

- When Monitored:
Ignition on.

- Set Condition:
The Exhaust Gas Temperature Sensor 1 Signal voltage is below.05 of a volt for 15 seconds.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, record all Freeze frame data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 30 seconds.
5. Turn the ignition on.
6. With the scan tool, read DTCs.

Did the DTC reset?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. TEMPERATURE SENSOR
1. While monitoring the scan tool, disconnect the Exhaust Temperature Sensor 1.

NOTE: Check connectors - Clean/repair as necessary.

Does DTC P0546 become active?

Yes

- Replace the Exhaust Temperature Sensor 1.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 3

3. (K185) EXHAUST TEMPERATURE SENSOR 1 SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT




1. Turn the ignition off.
2. Disconnect the ECM C2 harness connector.

NOTE: Check connectors - Clean/repair as necessary.

3. Measure the resistance between the (K185) Exhaust Temperature Sensor 1 Signal circuit and (K900) Sensor Ground circuit at the ECM C2 harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short between the (K185) Exhaust Temperature Sensor 1 Signal circuit and (K900) Sensor Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 4

4. (K185) EXHAUST TEMPERATURE SENSOR 1 SIGNAL CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the (K185) Exhaust Temperature 1 Sensor Signal circuit at the ECM C2 harness connector.

Is the resistance less than 10k Ohms?

Yes

- Repair the short to ground in the (K185) Exhaust Temperature 1 Sensor Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the Engine Control Module (ECM).
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. (K900) SENSOR GROUND CIRCUIT OPEN




1. Measure the resistance of the (K900) Sensor Ground circuit between the Exhaust Temperature 1 Sensor harness connector and the ECM C2 harness connector.

Is the resistance less than 1.00 Ohms?

Yes

- Go To 6

No

- Repair the open or high resistance in the (K900) Sensor Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

6. (K185) EXHAUST TEMPERATURE 1 SIGNAL CIRCUIT SHORTED TO ANOTHER CIRCUIT




1. Measure resistance from (K185) Exhaust Temperature 1 Signal circuit to all other circuits at the ECM C2 harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the circuits that are shorted together.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 7

7. ENGINE CONTROL MODULE (ECM)




1. Reconnect the ECM harness connector.
2. While monitoring the Exhaust Temperature Sensor 1 with scan tool, use a jumper wire and connect the sensor (K185) Exhaust Temperature 1 Signal circuit to the sensor (K900) Sensor ground wire at the sensor connector.

Did the DTC for voltage high go inactive and the DTC for voltage low become active?

Yes

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

No

- Replace the Engine Control Module (ECM).
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

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