Differential pressure sensor(DPS) is piezzo electric type sensor. Sensing the differential pressure between in front of CPF and in the back of CPF, DPS outputs linear signal from 0~5V. Using output signal, DPS detects the amount of soot, sulfide, SOF(soluble organic fraction) to determine if CPF regeneration is needed.
※CPF regeneration : When vehicle is in steady speed condition and above normal engine loading condition, if differential pressure between before and after CPF is above the specified pressure, ECM considers that stored soot inside of CPF is excessive. In this condition, exhaust gas tempt. is raised by post injection 1 and 2 to warm CPF up to 550℃~650℃. In this high tempt, soot inside of CPF burns up naturally and this mechanism is called as "CPF regeneration".Most of soot is burned up during regeneration process but a little amount of soot is not burned up and stored inside of CPF continuously. The stored soot decreases the efficiency of CPF slowly. DPS corrects CPF regeneration period and duration as comparing and calculating the differential pressure due to stored soot with the total distance covered.
P1403 is set when outdoor temp. is -5℃ and failure ID signal is outputted as 1. If differncial pressure does not change or it is extremly low, ECM recognizes hose line to be faulty. This code is likely to be set when vehicle is parked at a slope with front side of vehicle headed to downward.
Item | Detecting Condition | Possible Cause | ||
DTC Strategy | ● Voltage monitoring | ● Water freezing ● DPS Wiring ● DPS component ● Reversly connectedDPS hose line ● Clogged DPS hose ● Clogged CPF inlet section ● Clogged CPF | ||
Enable Conditions | ● Engine running | |||
Threshold Value | ● Abnormal signal outputted at below -5℃ of outdoor temp. | |||
Diagnostic Time | ● Immediately | |||
Fail Safe | Fuel cut | NO | ||
EGR Off | NO | |||
Fuel Limit | NO | |||
Check Lamp | NO | |||
As accelerating, DPS signal output voltage does not vary too much. Even when accelerator pedal is fully depressed, the signal voltage fluctuates just a little bit like "Fig. 2". However, the more CPF is used, the more waveform fluctuates.
Connect Scantool to Data Link Connector (DLC).
When atmospheric temp. is below 0℃, monitor data as soon as turning engine ON.
Turn "OFF" electrical devices and A/C.
Monitor "DIFFERENTIAL PRESSURE" and "PRESSURE PRE CPF" parameter on the scantool.
specification : "DIFFERENTIAL PRESSURE" and "PRESSURE PRE CPF" data vary normally.
even at the temperature of below 0℃
※ When data do not vary
☞ Check if diconnected differential pressure sensing hose or pressure leakage is detected. Check if the deformation(which may disturb water flow) of the steel pipe connecting CPF and DIFFERENTIAL PRESSURE SENSOR as well.
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 "Power Circuit Inspection".
IG KEY "OFF", ENGINE "OFF"
Disconnect DPS connector.
IG KEY "ON"
Measure the voltage of DPS connector terminal 1.
Specification : 4.8V~5.1V
Is the measured voltage within the specification?
▶ Go to "Signal Circuit Inspection".
▶ Repair open in power circuit and go to "Verification of Vehicle Repair".
Check signal circuit voltage
IG KEY "OFF", ENGINE "OFF"
Disconnect DPS connector.
IG KEY "ON"
Measure the voltage of DPS connector terminal 2.
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".
Check open in signal circuit
IG KEY "OFF", ENGINE "OFF"
Disconnect DPS connector and ECM connector.
Check continuity between DPS connector terminal 2 and ECM connector(C244-K) terminal 36.
Specification : Continuity (below 1.0Ω)
Is the measured resistance within the specification?
▶ Go to "3. Check short to ground in signal circuit".
▶ Repair open in signal circuit and go to "Verification of Vehicle Repair".
Check short in signal circuit
IG KEY "OFF", ENGINE "OFF"
Disconnect DPS connector and ECM connector.
IG KEY "ON"
Check continutity between DPS connector terminal 2 and chassis ground. ( Test for short to ground )
Check voltage between DPS connector terminal 2 and chassis ground. ( Test for short to battery )
Specification : Test for short to ground : Discontinuity (Infinite Ω )
Test for short to battery : below 0.1 V
Is the isolation of DPS signal circuit normal?
▶ Go to "Ground Circuit Inspection".
▶ Repair short in signal circuit and go to "Verification of Vehicle Repair".
IG KEY "OFF", ENGINE "OFF"
Disconnect EGTS connector.
IG KEY "ON"
Measure the voltage of DPS connector terminal 2. [ TEST "A" ]
Measure the voltage between DPS connector terminal 2 and 3. [ TEST "B" ]
( terminal 2 : Check + prove , terminal 3 : 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".
DPS visual inspection
IG KEY "OFF", ENGINE "OFF"
Disconnect DPS connector.
Check DPS terminals for corrosion and contamination.
Check (1)connecting condition of DPS and pressure sensing hose, (2)exhaust gas pressure leakate, (3)miss connection of pressure sensing hose (reverse connection) is detected.
Is DPS related problem detected?
▶ If needed, replace DPS or pressure sensing hose and go to "Verification of Vehicle Repair".
▶ Go to "2. Monitor DPS signal waveform" as follows.
Monitor DPS signal waveform
IG KEY "ON", ENGINE "OFF"
Connect DPS connector.
Connect oscilloscope to DPS connector terminal 2.
After warming engine up, monitor the waveform at idle and during acceleration.
Specification : Refer to "Signal Waveform ＆ Data" of "General Information".
Is DPS signal waveform is similar to the waveform of "Signal Waveform ＆ Data"?
▶ Go to "Verification of Vehicle Repair".
▶ Replace DPS and go to "Verification of Vehicle Repair".
After a repair, it is essential to verify that the fault is corrected.
After connecting Scantool select "DIAGNOSTIC TROUBLE CODES(DTCs)" mode.
Clear recorded DTC using Scantool.
Drive the vehicle within DTC "Enable conditions" in "General information".
After selecting "DIAGNOSTIC TROUBLE CODES(DTCs)" mode and check if DTC is recorded again.
Are any DTCs recorded ?
▶ Go to the DTC guide of recorded NO. in Scantool.
▶ System operates within specification.
