Tip & How-To about Mercedes-Benz E-Class

DFPE Differential Feedback Pressure Exhaust sensor

1.7) DFPE - Differential Feedback Pressure Exhaust (sensor)


What is it? This is an electrical device that measures the differential pressure between two ports on the pipe that supplies the exhaust gases to the EGR.


Where is it located? The DFPE is located near to both the EGR and the exhaust feed-pipe to the EGR. THE DFPE makes two piped connections to the exhaust feed-pipe in front of the EGR valve


How does it work? The two pipes on the exhaust feed-pipe are connected at two separate sites. When exhaust flows through the feed-pipe it creates a differential in pressure between the two ports and the DPFE detects this and responds by altering a voltage output to the ECU. The ECU is able to detect for how long and by how much the EGR is open by monitoring the DFPE output. Until the engine has warmed the DFPE signal should indicate no EGR activity as the ECU disables the EGR from opening when coolant (engine) temperature readings are low. The EGR is kept closed by either the ECU not sending voltage to the EGR actuator (in cases of direct motor/solenoid control of the EGR) or by not charging the vacuum control solenoid valve on the vacuum line to the EGR (in cases where vacuum is used to actuate the EGR).



Symptoms of faulty DFPE


The DFPE may misread the differential pressure leading to the ECU opening or closing the EGR valve at the wrong time. The symptoms mimic very much the effects of a faulty EGR namely:-


  • Erratic idling - if DFPE signals 'no pressure' in error and ECU opens the EGR valve.
  • Misfire ('pinking') - if DFPE detects 'pressure' in error and ECU keeps EGR closed.


Note: Sometimes a DPFE fault can be misdiagnosed:

1) If the coolant temperature sensor is at fault and sends an incorrect 'the engine is warm' signal then the ECU responds by opening the EGR valve prematurely causing the engine to stumble and stall. This pattern looks very much like a fault from the DPFE when in fact the DPFE might be working perfectly.

2) If the vacuum control valve fails to open when instructed. Apply 5 volts between the socket pins on the valve to check for valve opening.


How to Check? Applying pressure to one or the other ports on the DPFE should result in a change in electrical output as detected by a volt meter. No change in voltage output indicates the DFPE is faulty.


How to Fix? Make sure the pipes to the DFPE are free of leaks and clear of carbon deposits. If the DFPE is itself faulty then it must be replaced.



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Code p1400 gmc enjoy 2007 what is the problem in this code


Definition of Diagnostic Trouble Code P1400 Audi: EGR Valve Circ Electrical Malfunction BMW: Heated Catalyst Battery Voltage or Current too Low during Heating (Bank 1) Chrysler: Manifold Differential Pressure Sensor Circuit Malfunction Dodge: Manifold Differential Pressure Sensor Circuit Malfunction Ford: Differential Pressure Feedback EGR Circuit Low Input Hyundai: EGR System Monitor Malfunction Infiniti: EGRC Solenoid/V Jaguar: Exhaust Gas Recirculation Valve Position Control Jeep: Manifold Differential Pressure Sensor Circuit Malfunction Lexus: Sub-TPS Malfunction Lincoln: Differential Pressure Feedback EGR Circuit Low Input Mazda: DPFE Sensor Circuit Low Input Mercedes: EGR Switchover Valve Malfunction (C230 Only) Mercury: Differential Pressure Feedback EGR Circuit Low Input Mitsubishi: Manifold Differential Pressure Sensor Circuit Malfunction Nissan: Differential Pressure Feedback EGR Circuit Low Input Subaru: Fuel Tank Pressure Control Solenoid Circuit Low Input Toyota: Sub-Throttle Position Sensor Malfunction Volkswagen: EGR Valve Circ Electrical Malfunction

Jun 20, 2015 | 2007 GMC Envoy Denali

1 Answer

1401 egr code


P1401 FORD - DPFE Sensor Circuit High
Faulty Differential Pressure Feedback Electronic (DPFE) sensor
- Differential Pressure Feedback Electronic (DPFE) sensor harness is open or shorted
- Differential Pressure Feedback Electronic (DPFE) sensor circuit poor electrical connection. This is not likely the EGR but the EGR pressure sensing valve.

Oct 19, 2012 | Cars & Trucks

2 Answers

Need to find and replace the DPFE-15 sensor. Dealership diagnosed when service engine light came on and saaid this is what needed replacing. Problem is I do not know where to find it on the engine.


Exhaust Gas Recirculation (EGR) System The exhaust gas recirculation (EGR) system is designed to:
  • reintroduce exhaust gas into the combustion cycle.
  • lower combustion temperatures.
  • reduce the formation of oxides or nitrogen (NOX).
The amount of exhaust gas reintroduced and the timing of the cycle varies by calibration. Timing and volume are controlled by the following:
  • engine rpm
  • engine vacuum
  • exhaust system back pressure
  • engine coolant temperature
  • air charge temperature
  • throttle position
The EGR valve (EGR valve) (9D475) is vacuum-actuated. The vacuum hose routing diagram is shown on the Vehicle Emission Control Information (VECI) decal. The EGR system is a differential pressure feedback EGR Sensor system. Differential pressure feedback EGR Sensor is a subsonic closed loop EGR system. The differential pressure feedback EGR system:
  • monitors EGR flow rate by the pressure drop across the metering orifice located in the EGR tube.
  • uses a differential pressure feedback EGR sensor as the feedback device.
  • uses the EGR valve only as a pressure regulator, rather than a flow metering device.
  • controlled pressure is varied by the valve movement using vacuum output of the EGR vacuum regulator solenoid (9J459).
  • allows for a more accurate assessment of EGR flow requirements.


Differential Pressure Feedback EGR Flow Diagram


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Differential Pressure Feedback EGR Sensor Removal
  1. Disconnect engine control sensor wiring (12A581) from Differential Pressure Feedback EGR Sensor.
  1. Disconnect Differential Pressure Feedback EGR Sensor hoses from EGR valve to exhaust manifold tube (9D477).
  1. Remove retaining nuts or bolts (depending upon application) and EGR Differential Pressure Feedback transducer.
Installation
  1. Follow removal procedure in reverse order.
  1. Tighten retaining nuts or bolts (depending upon application) to 5-7 Nm (45-61 lb-in).


    Differential Pressure Feedback EGR Sensor, 3.0L (2V) Engine


    aa0036a.gif



    Differential Pressure Feedback EGR Sensor, 3.0L (4V) Engine


    a23840a.gif


    Item Part Number Description 1 6049 RH Cylinder Head 2 - Differential Pressure Feedback EGR Sensor 3 - Nut (2 Req'd) 4 - Stud Bolt 5 - Bolt (2 Req'd) 6 - Differential Pressure Feedback EGR Sensor Bracket A - Tighten to 5-7 Nm (45-61 Lb-In) B - Tighten to 8-12 Nm (71-106 Lb-In)

    Engine Emission Control Component Location-3.4L SHO Engine


    a25013a.gif


    Item Part Number Description 1 95607-05200 Nut 2 - EGR Sensor Hose 3 - EGR Sensor Hose 4 95027-08016 Bolt 5 - Differential Pressure Feedback EGR Sensor 6 9J433 Differential Pressure Feedback EGR Sensor Mounting Bracket 7 9D474 EGR Solenoid Vacuum Valve (2 Req'd) 8 A4670 Vacuum Tube Assembly 9 9424 Intake Manifold 10 9J459 EGR Vacuum Regulator Solenoid A - Tighten to 5-7 Nm (45-61 Lb-In)
Hope this helps

Aug 14, 2011 | 1999 Ford Taurus

2 Answers

my code reader says p1401 ford exscape


p 1401 is a code for differential pressure feedback egr circuit high input there is a small square sensor on the engine with a vacuum line here is some info Exhaust Gas Recirculation (EGR) System Monitor” Differential Pressure Feedback EGR
The Differential Pressure Feedback EGR System Monitor is an on-board strategy designed to test the integrity and flow characteristics of the EGR system. The monitor is activated during EGR system operation and after certain base engine conditions are satisfied. Input from the ECT, IAT, TP and CKP sensors is required to activate the EGR System Monitor. Once activated, the EGR System Monitor will perform each of the tests described below during the engine modes and conditions indicated. Some of the EGR System Monitor tests are also performed during on demand self-test.

The Differential Pressure Feedback EGR sensor and circuit are continuously tested for opens and shorts. The monitor looks for the Differential Pressure Feedback EGR circuit voltage to exceed the maximum or minimum allowable limits.

The DTCs associated with this test are DTCs P1400 and P1401.
The EGR Vacuum Regulator solenoid is continuously tested for opens and shorts. The monitor looks for an EGR Vacuum Regulator circuit voltage that is inconsistent with the EGR Vacuum Regulator circuit commanded output state.

Jul 26, 2010 | 2001 Ford Escape

1 Answer

egr vacuum solenoid


Exhaust Gas Recirculation (EGR) System Monitor—Differential Pressure Feedback EGR The Differential Pressure Feedback EGR System Monitor is an on-board strategy designed to test the integrity and flow characteristics of the EGR system. The monitor is activated during EGR system operation and after certain base engine conditions are satisfied. Input from the ECT, CHT, IAT, TP and CKP sensors is required to activate the EGR System Monitor. Once activated, the EGR System Monitor will perform each of the tests described below during the engine modes and conditions indicated. Some of the EGR System Monitor tests are also performed during on demand self-test.
  1. The differential pressure feedback EGR sensor and circuit are continuously tested for opens and shorts. The monitor looks for the Differential Pressure Feedback EGR circuit voltage to exceed the maximum or minimum allowable limits.

    The DTCs associated with this test are DTCs P1400 and P1401.
  1. The EGR vacuum regulator solenoid is continuously tested for opens and shorts. The monitor looks for an EGR Vacuum Regulator circuit voltage that is inconsistent with the EGR Vacuum Regulator circuit commanded output state.

    The DTC associated with this test is DTC P1409.
  1. The test for a stuck open EGR valve or EGR flow at idle is continuously performed whenever at idle (TP sensor indicating closed throttle). The monitor compares the Differential Pressure Feedback EGR circuit voltage at idle to the Differential Pressure Feedback EGR circuit voltage stored during key on engine off to determine if EGR flow is present at idle.

    The DTC associated with this test is DTC P0402.
  1. The differential pressure feedback EGR sensor upstream hose is tested once per drive cycle for disconnect and plugging. The test is performed with EGR valve closed and during a period of acceleration. The PCM will momentarily command the EGR valve closed. The monitor looks for the differential pressure feedback EGR sensor voltage to be inconsistent for a no flow voltage. A voltage increase or decrease during acceleration while the EGR valve is closed may indicate a fault with the signal hose during this test.

    The DTC associated with this test is DTC P1405.
  1. The EGR flow rate test is performed during a steady state when engine speed and load are moderate and EGR vacuum regulator duty cycle is high. The monitor compares the actual Differential Pressure Feedback EGR circuit voltage to a desired EGR flow voltage for that state to determine if EGR flow rate is acceptable or insufficient. This is a system test and may trigger a DTC for any fault causing the EGR system to fail.

    The DTC associated with this test is DTC P0401. DTC P1408 is similar to P0401 but performed during KOER Self-Test conditions.
  1. The MIL is activated after one of the above tests fails on two consecutive drive cycles.
0a01005.gif EGR Vacuum Regulator Solenoid The EGR vacuum regulator solenoid (Figure 88) is an electromagnetic device which is used to regulate the vacuum supply to the EGR valve. The solenoid contains a coil which magnetically controls the position of a disc to regulate the vacuum. As the duty cycle to the coil increases, the vacuum signal passed through the solenoid to the EGR valve also increases. Vacuum not directed to the EGR valve is vented through the solenoid vent to atmosphere. Note that at 0% duty cycle (no electrical signal applied), the EGR vacuum regulator solenoid allows some vacuum to pass, but not enough to open the EGR valve.

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Exhaust Gas Recirculation (EGR) Vacuum Regulator Solenoid Removal and Installation
  1. Disconnect the battery ground cable (14301). For additional information, refer to Section 414-01 .
  1. Disconnect the vacuum hoses and the EVR solenoid electrical connector.
  1. Remove the two nuts and the EVR solenoid (9J459).
From the looks of the rubber mounting, I would say it's mounted on the cowl (firewall) on the passenger side in the engine compartment.

Please rate as fixya if this helps. Thanks

Feb 24, 2009 | 2001 Ford Escort ZX2

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