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DPFE Sensor Malfunction

DTC P1400, P1401 DETECTION CONDITION AND POSSIBLE CAUSES

DTC P1400, P1401 DPFE SENSOR MALFUNCTION
DETECTION CONDITION 
  • Average voltage of DPFE SIG circuit input below minimum (DTC P1400).
  • Average voltage of DPFE SIG circuit input above maximum (DTC P1401).
POSSIBLE CAUSE 
  • Leaking upstream pressure hose.
  • DPFE SIG shorted to GND.
  • DPFE SIG open.
  • DPFE SIG shorted to PWR.
  • VREF shorted to PWR.
  • VREF shorted to GND.
  • SIG RTN open.
  • Damaged DPFE sensor.
  • Damaged PCM.
DTC P1400, P1401 INSPECTION

STEP INSPECTION ACTION
1 DTC P1400: VERIFY DIFFERENTIAL PRESSURE FEEDBACK EGR (DPFE) VOLTAGE
  • Key On Engine Off (KOEO).
  • Access DPFEGR PID with a NGS Tester.
  • Was DPFEGR PID voltage less than 0.2 volt? 
 Yes The DPFE sensor voltage is less than the acceptable minimum.
Go to step 2.
No Fault is intermittent.
GO to step 14.
2 INDUCE OPPOSITE DPFE SENSOR VOLTAGE
  • Disconnect DPFE sensor connector. See ELECTRICAL COMPONENT LOCATOR article.
  • Key On Engine Off (KOEO).
  • Access DPFEGR PID with a NGS Tester.
  • Is DPFEGR PID value between 4.0 and 6.0 volts? 
 Yes Replace DPFE sensor.
GO to step 15.
No Go to step 3.
3 MEASURE VREF VOLTAGE AT DPFE SENSOR VEHICLE HARNESS CONNECTOR
  • Measure voltage between VREF BR/W and SIG RTN GY/R circuits at the DPFE sensor harness connector.
  • Was VREF voltage between 4.0 and 6.0 volts? 
 Yes Go to step 4.
No VREF voltage is out of range.
See TEST 1: VEHICLE REFERENCE VOLTAGE (VREF)  .
4 CHECK DPFE CIRCUIT FOR SHORTS TO GROUND AND SIG RTN
  • Disconnect NGS Tester from DLC.
  • Install Breakout Box, leave PCM disconnected.
  • Measure resistance between PCM test pin 65 (DPFE SIG) and PCM test pin 91 (SIG RTN)
  • Measure resistance between PCM test pin 65 (DPFE SIG) and PCM test pins 51 or 103 (PWRGND).
  • Is each resistance greater than 10,000 ohms? 
 Yes Replace PCM. See POWERTRAIN CONTROL MODULE .
GO to step 15.
No Repair short circuit.
GO to step 15.
5 DTC P1401: VERIFY DPFEEG PID VOLTAGE
  • Key On Engine Off (KOEO).
  • Access DPFEGR PID with a NGS Tester.
  • Key OFF.
  • Was DPFEGR PID voltage greater than 4.0 volts? 
 Yes The DPFE sensor voltage is greater than the acceptable maximum.
Go to step 6.
No The fault is intermittent.
GO to step 14.
6 CHECK DPFE FOR SHORT TO PWR
  • Disconnect DPFE sensor harness connector.
  • Key On Engine Off (KOEO).
  • Measure voltage between DPFE circuit BR/LG at the DPFE sensor harness connector and battery ground.
  • Key OFF.
  • Was voltage greater than 10.5 volts? 
 Yes The DPFE sensor voltage input is indicating a short to PWR.
Go to step 7.
No Go to step 8.
7 CHECK DPFE FOR SHORT TO PWR IN HARNESS
  • Install Breakout Box, leave PCM disconnected.
  • Key On Engine Off (KOEO).
  • Measure voltage between PCM test pin 65 (DPFE SIG) and PCM test pins 51 and 103 (PWR GND).
  • Key OFF.
  • Was voltage greater than 10.5 volts? 
 Yes Repair short circuit.
GO to step 15.
No Replace PCM. See POWERTRAIN CONTROL MODULE .
GO to step 15.
8 INDUCE OPPOSITE DPFE SENSOR VOLTAGE
  • Connect a jumper wire between the sensor DPFE BR/LG and SIG RTN circuits GY/R at the DPFE sensor harness connection.
    NOTE: If a NGS Tester communication concern exists, remove jumper immediately and go to step 14.
  • Access DPFEGR PID with NGS Tester.
  • Key OFF.
  • Was DPFEGR PID voltage less than 0.05 volt? 
 Yes Remove jumper.
Go to step 9.
No Unable to induce opposite signal.
GO to step 11.
9 VERIFY THAT VREF IS IN RANGE
  • Key On Engine Off (KOEO).
  • Measure voltage between the sensor VREF BR/W and SIG RTN circuits GY/R at DPFE sensor harness connector.
  • Key OFF.
  • Was VREF voltage between 4.0 and 6.0 Volts? 
 Yes Go to step 10.
No VREF is out of range.
See TEST 1: VEHICLE REFERENCE VOLTAGE (VREF)  .
10 CHECK DPFE FOR SHORT TO VREF IN HARNESS
  • Install Breakout Box, leave PCM disconnected.
  • Measure resistance between PCM test pin 65 (DPFE SIG) and test pin 90 (VREF).
  • Is resistance greater than 10,000 ohms? 
 Yes Replace DPFE sensor.
GO to step 15.
No Repair short circuit.
GO to step 15.
11 CHECK DPFE CIRCUIT FOR OPEN IN HARNESS
  • Install Breakout Box, leave PCM disconnected.
  • Measure resistance between PCM test pin 65 (DPFE SIG) and DPFE SIG circuit at the DPFE sensor harness connector.
  • Is resistance less than 5.0 ohms? 
 Yes GO to step 12.
No Repair open circuit.
GO to step 15.
12 CHECK SIG RTN FOR OPEN IN HARNESS
  • Measure resistance between PCM test pin 91 (SIG RTN) and SIG RTN GY/R circuit at the DPFE sensor harness connector.
  • Is resistance less than 5.0 ohms? 
 Yes Replace PCM. See POWERTRAIN CONTROL MODULE .
GO to step 15.
No Repair open circuit.
GO to step 15.
13 CHECK DPFE SIG FOR SHORT TO VREF IN HARNESS
  • Install Breakout Box, leave PCM disconnected.
  • Measure resistance between PCM test pin 65 (DPFE SIG) and PCM test pin 90 (VREF).
  • Is resistance greater than 10,000 ohms? 
 Yes Replace PCM. See POWERTRAIN CONTROL MODULE .
GO to step 15.
No Repair short circuit.
GO to step 15.
14 WIGGLE TEST DPFE SENSOR AND HARNESS
  • Key On Engine Off (KOEO).
  • Access DPFEGR PID with NGS Tester.
  • Observe DPFEGR PID for an indication of fault while performing the following: 
  • Lightly tap on DPFE sensor; wiggle the DPFE sensor connector and vehicle harness between sensor and PCM. A fault is indicated by a sudden change in DPFEGR PID voltage.
  • Is a fault indicated? 
 Yes Isolate fault and repair as necessary.
Go to step 15.
No Unable to duplicate or identify fault at this time. GO to
See TEST 4: INTERMITTENT  with DPFEGR PID data and list of possible causes.
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DTC P1405, P1406 DETECTION CONDITION AND POSSIBLE CAUSES

DTC P1405, P1406 DPFE SENSOR MALFUNCTION
DETECTION CONDITION 
  • Exhaust manifold side (upstream) DPFE sensor pressure hose is off or plugged (DTC P1405).
  • Intake manifold side (downstream ) DPFE sensor pressure hose is off or plugged (DTC P1406).
POSSIBLE CAUSE 
  • Improper upstream or downstream pressure hose connection.
  • Upstream or downstream pressure hose plugged.
  • Plugged or damaged pressure pickup tubes.
DTC P1405, P1406 INSPECTION

STEP INSPECTION ACTION
1 INSPECT UPSTREAM (DTC P1405) AND/OR DOWNSTREAM (DTC P1406) PRESSURE HOSE CONNECTIONS
NOTE: If DTC P1406 is currently present, DTC P1408 will be in output in Key On Engine Running (KOER) Self Test
  • Inspect upstream or downstream hose at DPFE sensor and orifice tube assembly for disconnect or poor connection. See ELECTRICAL COMPONENT LOCATOR article.
  • Is hose off or poorly connected? 
 Yes Reconnect hose(s) or repair as necessary.
Perform EGR Monitor Repair Verification Drive Cycle.
See DRIVE CYCLES  .
No Go to step 2.
2 INSPECT UPSTREAM (DTC P1405) AND/OR DOWNSTREAM (DTC P1406) PRESSURE HOSE FOR PLUGGING
NOTE: It is essential that the DPFE pressure hose is the correct service part and not a substitute.
  • Visually inspect upstream or downstream hose routing. Hose should not be pinched or have dips in it where water could settle and freeze.
  • Remove upstream or downstream hose and carefully inspect for plugging, water or leaks.
  • Is there a fault detected in the hose? 
 Yes Repair or replace hose(s) as necessary.
Perform EGR Monitor Repair Verification Drive Cycle.
See DRIVE CYCLES  .
No Go to step 3.
3 CHECK ORIFICE TUBE ASSEMBLY AND DPFE SENSOR
  • Inspect connections at the DPFE sensor for plugging or damage at sensor. See ELECTRICAL COMPONENT LOCATOR .
  • Inspect the exhaust and intake manifold side pressure pickup tube and orifice tube assembly for plugging, loose connection or damage.
  • Is DPFE sensor or orifice tube assembly plugged, loose or damaged? 
 Yes Repair or replace DPFE sensor or orifice tube assembly as necessary.
Go to step 5.
Perform EGR Monitor Repair Verification Drive Cycle.
See DRIVE CYCLES  .
No Go to step 4.
4 CHECK DPFE SENSOR OUTPUT BY APPLYING VACUUM WITH HAND PUMP
  • Disconnect pressure hoses at DPFE sensor.
  • Connect a hand vacuum pump to downstream connection at sensor (intake manifold side of sensor or the smaller diameter pickup tube), o Key On Engine Off (KOEO).
  • Access DPFEGR PID with NGS Tester and note PID value.
  • Apply 27-30 kPa (8-9 in-Hg) vacuum to the DPFE sensor and hold for a few seconds.
  • Quickly release vacuum.
    • The DPFEGR PID voltage must be between 0.2 and 1.3 volt with the key on and no vacuum applied.
    • The DPFEGR PID voltage must increase to greater than 4.0 volts with vacuum applied.
    • The DPFEGR PID voltage should drop to less than 1.5 volts in less than 3 seconds when vacuum is released.
    • Key OFF.
  • Does DPFEGR PID voltage indicate a fault in the DPFE sensor? 
 Yes Replace DPFE sensor.

Perform EGR Monitor Repair Verification Drive Cycle.


See DRIVE CYCLES  .
No Fault not found.
See TEST 4: INTERMITTENT  .
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