In EURO4 diesel engine with CPF, injection is devided into 2 pilot, 1 main, 2 post injections. Among these injections, pilot and main injections are for the operation of engine, however post injections are for CPF regeneration. Only in activating condition of CPF regeneration during driving, post injection starts. 1st post injection happens at the end of combustion cycle then, injected fuel is used to raise exhaust temperature. that temp. is sensed at T3 exhaust tempt. sensor which is ahead of Turbo charger. 2nd post injection happens at exhaust cycle then, injected fuel is also used to raise exhaust temperature. that temp. is sensed T5 exhaust tempt. sensor which is between Oxydation catalyst and CPF. The reason of raising exhaust tempt. is because exhaust tempt. in diesel engine is too low for CPF regeneration. The optimum tempt. for CPF regeneration is 550~600℃ thus, the goal of post injection is raise exhaust tempt. to that range of tempt.. However if exhaust tempt. is too high, turbo charger or CPF are likely to be damaged. Therefore if tempt. measured at each sensor is out of permittable value(specification), ECM deactivates CPF regeneration.
P0546 is set when the Exhaust gas temperature sensor(EGTS) - VST signal is detected over maximum set temperature(890℃),- In case that exhaust gas temperature on the front side of VGT is abnormally increased -, for more than 1sec. Therefore, check component or vehicle is driven in severe driving condition.
*. In case that real exhaust gas temperature reaches up to 900℃, engine and exhaust line(Turbo charger), CPF can be damaged.
Item | Detecting Condition | Possible Cause | ||
DTC Strategy | ● Voltage monitoring | ● Abnormal over-load (driving) condition ● Exhaust gas temp. sensor(T3-VGT) wiring ● Exhaust gas temp. sensor(T3-VGT) component | ||
Enable Conditions | ● IG KEY "ON" | |||
Threshold Value | ● Exhaust gas temp. exceeds 900℃(EGTS-VGT) | |||
Diagnostic Time | ● 1.0 sec. | |||
Fail Safe | Fuel Cut | NO | ||
EGR Off | NO | |||
Fuel Limit | NO | |||
Check Lamp | OFF | |||
Temp. (℃) | Nominal (kΩ) | NEW | AGED | ||
Min(kΩ) | Max(kΩ) | Min(kΩ) | Max(kΩ) | ||
100 | 371 | 289 | 481 | 272 | 515 |
300 | 5.92 | 5.3 | 6.61 | 5.15 | 6.79 |
600 | 0.363 | 0.347 | 0.379 | 0.341 | 0.386 |
900 | 0.0893 | 0.0842 | 0.0949 | 0.0833 | 0.096 |
Fig.1) 4.8V is outputted at EGTS output signal circuit, when exhaust gas temp. is approx.150℃.
When exhaust gas temp. is 550~600℃ at CPF regeneration, output voltage drops to 0.3~0.4V.
Connect GDS to Data Link Connector (DLC).
Warm engine up to normal operating temperature.
Turn "OFF" electrical devices and A/C.
Monitor "E/GAS TEMP. PRE VGT","E/GAS TEMP. PRE CPF" parameter on the GDS.
Specification : "E/GAS TEMP." is displayed.
Fig.1) "EXHAUST GAS TEMP." at idle is shown. Monitor if abnormall difference between "Fig. 1) data" and the data from the vehicle to test.
Electrical systems consist of a lot of harness and connectors, poor connection of terminals can cause various problems and damge of component.
Perform checking procedure as follows.
Check damage of harness and terminals : Check terminals for contact resistance, corrosion and deformation.
Check connecting condition of ECM and component connector : Check terminal seperation, damage of locking device and connecting condition between terminal and wiring.
Disconnect the pin which requires checking at male connector and insert it to the terminal at female connector for checking connecting condition. ( after checking, reconnect the pin at correct position. )
Is the problem found?
 | ▶ Repair the trouble causing part and go to "Verification of Vehicle Repair". |
 | ▶ Go to "Signal Circuit Inspection ". |
Check signal circuit voltage
IG KEY "OFF", ENGINE "OFF"
Disconnect EGTS(T3-VGT) connector.
IG KEY "ON"
Measure the voltage between signal terminal of EGTS(T3-VGT) harness connector.
Specification : 4.8V~5.1V
Is the measured voltage within the specification?
| ▶ Go to "Ground Circuit Inspection". |
| ▶ Go to "2.Check open in signal circuit" as follows. |
Check open in signal circuit
IG KEY "OFF", ENGINE "OFF"
Disconnect EGTS(T3-VGT) connector and ECM connector.
Check the resistance between signal terminal of EGTS(T3-VGT) harness connector and EGTS signal terminal of ECM harness connector.
Specification : Continuity ( below 1.0Ω )
Is the measured resistance within the specification?
| ▶ Go to "3. Check short to ground in signal circuit"as follows. |
| ▶ Repair open in signal circuit and go to "Verification of Vehicle Repair". |
Check short to ground in signal circuit
IG KEY "OFF", ENGINE "OFF"
Disconnect EGTS(T3-VGT) connector and ECM connector.
Check the resistance between signal terminal of EGTS(T3-VGT) harness connector and chassis ground.
Specification : Discontinuity ( Infinite Ω )
Is the measured resistance within the specification?
| ▶ Go to "Ground Circuit Inspection". |
| ▶ Repair short to ground in signal circuit and go to "Verification of Vehicle Repair". |
IG KEY "OFF", ENGINE "OFF"
Disconnect EGTS(T3-VGT) connector.
IG KEY "ON"
Measure the voltage between signal terminal of EGTS(T3-VGT) harness connector and chassis ground. [ TEST "A" ]
Measure the voltage between signal terminal and ground terminal of EGTS(T3-VGT) harness connector. [ TEST "B" ]
( Signal terminal : Check + prove , Ground terminal : Check - prove )
Specification : [TEST "A"] Voltage - [TEST "B"] Voltage = below 200mV
Is the measured voltage within the specification?
| ▶ Go to "Component Inspection". |
| ▶ When "B" voltage is not detected : Repair open in ground circuit and go to "Verification of Vehicle Repair". ▶ When the voltage difference between "A" and "B" is above 200mV : Eliminate the causes of excessive resistance and go to "Verification of Vehicle Repair". |
IG KEY "OFF", ENGINE "OFF".
Disconnect EGTS(T3-VGT) connector.
Measure the resistance between signal terminal and ground terminal of EGTS(T3-VGT) connector. (Component side)
Temp. (℃) | Nominal (kΩ) | NEW | AGED | ||
Min(kΩ) | Max(kΩ) | Min(kΩ) | Max(kΩ) | ||
100 | 371 | 289 | 481 | 272 | 515 |
300 | 5.92 | 5.3 | 6.61 | 5.15 | 6.79 |
600 | 0.363 | 0.347 | 0.379 | 0.341 | 0.386 |
900 | 0.0893 | 0.0842 | 0.0949 | 0.0833 | 0.096 |
Is the measured resistance at certain temperature within the specified resisance range at the temperature?
| ▶ Go to "Verification of Vehicle Repair". |
| ▶ Replace EGTS(T3-VGT) and go to "Verification of Vehicle Repair". |
After a repair, it is essential to verify that the fault is corrected.
After connecting GDS select "Diagnostic Trouble Codes(DTCs)" mode to and then clear DTC.
Drive the vehicle within DTC Enable conditions in General information.
After selecting "Diagnostic Trouble Codes(DTCs)" mode and check DTC is recorded again.
Are any DTCs recorded ?
| ▶ Go to the DTC guide of recorded NO. in GDS |
| ▶ System operates within specification. |
