ECD SYSTEM, Diagnostic DTC:P0544, P0545, P0546

DTC Code	DTC Name
P0544	Exhaust GAS Temperature Sensor Circuit (Bank 1 Sensor 1)
P0545	Exhaust Gas Temperature Sensor Circuit Low (Bank 1 Sensor 1)
P0546	Exhaust Gas Temperature Sensor Circuit High (Bank 1 Sensor 1)

DESCRIPTION

The exhaust gas temperature sensors are installed in front of and behind the DPF (*1) catalytic converter to sense the exhaust gas temperature.

A thermistor built into the sensor changes its resistance value according to the exhaust gas temperature. The lower the exhaust gas temperature is, the greater the thermistor resistance value becomes. The exhaust gas temperature becomes, the lower the thermistor resistance value becomes.

The exhaust gas temperature sensor is connected to the ECM. The 5 V power source voltage in the ECM is applied to the exhaust gas temperature sensor from terminals THCI (bank 1 sensor 1) and THCO (bank 1 sensor 2) via resistor R.

The resistor R and the exhaust gas temperature sensor are connected in series. When the resistance value of the exhaust gas temperature sensor changes in accordance with changes in the exhaust gas temperature, the voltage at terminals THCI (bank 1 sensor 1) and THCO (bank 1 sensor 2) also changes. Based on these signals, when DPF catalyst regeneration is needed, the ECM operates the injector to obtain target upstream temperature of the DPF catalytic converter as mentioned through sensor 1. In addition, the ECM monitors the rate of DPF catalytic converter temperature increase using sensor 2.

*1: Diesel Particulate Filter

DTC No.	DTC Detection Condition	Trouble Area
P0544	Sensor 1 output is less than 0.2 V or more than 4.95 V for 8 seconds or more (1 trip detection logic)	Open or short in exhaust gas temperature sensor (on upstream) circuit Exhaust gas temperature sensor (on upstream) ECM
P0545	Sensor 1 output is less than 0.2 V for 8 seconds or more (1 trip detection logic)	Open or short in exhaust gas temperature sensor (on upstream) circuit Exhaust gas temperature sensor (on upstream) ECM
P0546	Sensor 1 output is more than 4.95 V for 8 seconds or more (1 trip detection logic)	Open or short in exhaust gas temperature sensor (on upstream) circuit Exhaust gas temperature sensor (on upstream) ECM

Tech Tips

Sensor 1 represents a sensor located upstream on the DPF catalytic converter.
Sensor 2 represents a sensor located downstream on the DPF catalytic converter.

After confirming DTC P0544, P0545, P0546, P2031, P2032, and P2033, check the upstream and downstream exhaust gas temperature by selecting the following menus on the tester: Powertrain / Engine and ECT / Initial Exhaust Temp (In) and Initial Exhaust Temp (Out).

Result

Condition	Exhaust Gas Temperature	Exhaust Gas Temperature Sensor Condition
Idling after warm-up	Constant at 50 to 700°C (122 to 1,292°F)	Normal
	0°C (32°F)	Short circuit
	1,000°C (1,832°F)	Open circuit

WIRING DIAGRAM

INSPECTION PROCEDURE

Note

After replacing the ECM, the new ECM needs registration Click here and initialization Click here.

PROCEDURE

READ VALUE USING INTELLIGENT TESTER (EXHAUST GAS TEMPERATURE)

Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.

Note

Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.
Connect the intelligent tester to the DLC3.
Turn the ignition switch to the ON position.
Turn the tester on.

Enter the following menu items: Powertrain / Engine and ECT / Initial Exhaust Temp (In) and Initial Exhaust Temp (Out) and read its value displayed on the intelligent tester.

Standard
Same as the actual exhaust gas temperature (50 to 700°C [122 to 1,292°F] during idling after warm-up), and varies after an engine speed of 3,000 rpm is maintained for 1 minute.

Result

Temperature Displayed	Proceed to
1,000°C (1,832°F)	A
0°C (32°F) (After warming up the engine)	B
OK: Same as the actual exhaust gas temperature (50 to 700°C [122 to 1,292°F] during idling after warm-up), and varies after maintaining the engine speed of 3,000 rpm for 1 minute after accelerating the engine from idling to 3,000 rpm	C

Tech Tips

If there is a short circuit, the intelligent tester will indicate 0°C (32°F).
If there is an open circuit, the intelligent tester will indicate 1,000°C (1,832°F).

READ VALUE USING INTELLIGENT TESTER (SHORT IN WIRE HARNESS) Click here

CHECK FOR INTERMITTENT PROBLEMS

READ VALUE USING INTELLIGENT TESTER (OPEN IN WIRE HARNESS)
1. Disconnect the exhaust gas temperature sensor connector.
2. Connect terminals 1 and 2 of the exhaust gas temperature sensor wire harness side connector.
3. Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.
  
  Note
  
  Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.
4. Connect the intelligent tester to the DLC 3.
5. Turn the ignition switch to the ON position.
6. Turn the tester on.
7. Enter the following menu items: Powertrain / Engine and ECT / Initial Exhaust Temp (In).
8. Read the value.
  
  Standard
  
  0°C (32°F)
9. Reconnect the exhaust gas temperature sensor connector.
NG
READ VALUE USING INTELLIGENT TESTER (OPEN IN ECM) Click here

OK

REPLACE EXHAUST GAS TEMPERATURE SENSOR
READ VALUE USING INTELLIGENT TESTER (OPEN IN ECM)
1. Disconnect the exhaust gas temperature sensor connector.
2. Connect terminals THCI and E2 of the ECM connectors.
  
  Tech Tips
  
  Before checking, do a visual and contact pressure check on the ECM connector.
3. Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.
  
  Note
  
  Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.
4. Connect the intelligent tester to the DLC3.
5. Turn the ignition switch to the ON position.
6. Turn the tester on.
7. Enter the following menu items: Powertrain / Engine and ECT / Initial Exhaust Temp (In).
8. Read the value.
  
  Standard
  
  0°C (32°F)
9. Reconnect the exhaust gas temperature sensor connector.
NG
REPLACE ECM

OK

REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - EXHAUST GAS TEMPERATURE SENSOR)
READ VALUE USING INTELLIGENT TESTER (SHORT IN WIRE HARNESS)
1. Disconnect the exhaust gas temperature sensor connector.
2. Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.
  
  Note
  
  Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.
3. Connect the intelligent tester to the DLC3.
4. Turn the ignition switch to the ON position.
5. Turn the tester on.
6. Enter the following menu items: Powertrain / Engine and ECT / Initial Exhaust Temp (In).
7. Read the value.
  
  Standard
  
  1,000°C (1,832°F)
8. Reconnect the exhaust gas temperature sensor connector.
NG
READ VALUE USING INTELLIGENT TESTER (SHORT IN ECM) Click here

OK
READ VALUE USING INTELLIGENT TESTER (SHORT IN ECM)
1. Disconnect the exhaust gas temperature sensor connector.
2. Disconnect the ECM connector.
3. Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.
  
  Note
  
  Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.
4. Connect the intelligent tester to the DLC3.
5. Turn the ignition switch to the ON position.
6. Turn the tester on.
7. Enter the following menu items: Powertrain / Engine and ECT / Initial Exhaust Temp (In).
8. Read the value.
  
  Standard
  
  1,000°C (1,832°F)
9. Reconnect the exhaust gas temperature sensor connector.
10. Reconnect the ECM connector.
NG
REPLACE ECM

OK

REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - EXHAUST GAS TEMPERATURE SENSOR)