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

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What are the probable cause(s) of DTC P1406?


Definition of Diagnostic Trouble Code P1406 Audi: EGR Temperature Sensor Range/Performance BMW: Heated Catalyst Internal Control Module Checksum/ROM Error Buick: EGR Valve Pintle Position Circuit Cadillac: EGR Valve Pintle Position Circuit Chevrolet: EGR Valve Pintle Position Circuit Ford: Differential Pressure Feedback Sensor Downstream Hose Off Or Plugged GMC: EGR Valve Pintle Position Circuit Isuzu: EGR Valve Pintle Position Circuit Lincoln: Differential Pressure Feedback Sensor Downstream Hose Off Or Plugged Mazda: DPFE Sensor Downstream Hose Off Or Plugged Mercury: Differential Pressure Feedback Sensor Downstream Hose Off Or Plugged Oldsmobile: EGR Valve Pintle Position Circuit Pontiac: EGR Valve Pintle Position Circuit Saturn: EGR Valve Pintle Position Circuit Toyota: Turbo Pressure Sensor Range/Performance Problem Volkswagen: EGR Temperature Sensor Range/Performance Volvo: Termperature Warning > 100 degrees C

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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

1 Answer

P1405


P1405- Differential pressure feedback sensor upstream hose off or plugged
It has to do with your EGR operation

The Differential feedback pressure sensor is located under the hood on the drivers side.

If you locate your EGR valve you will see a tube going from it to your exhaust manifold.

you will notice 2 small tubes leading from the large one feeding into a small sensor....this is the DPFE sensor which is throwing your code.

Now....the DPFE "could" be doing its job by telling you the orfice in the tube is plugged, but the DPFE is known to fail on these trucks.....but it throws a code P401....

It may be a good idea to try a new DPFE sensor before a new EGR tube.


Hope helps.

Mar 09, 2012 | 2003 Vauxhall Vectra

1 Answer

I replaced the EGR valve on the car and now have an error code indicating "EGR valve insufficient air flow..." I cleaned out a lot of carbon and junk that I could reach with a short piece of wire and pipe cleaners. How do I clean it properly? Thank you very much!


The air flow through the EGR is usually detected by a DPFE (differential Pressure Feedback Exhaust) sensor. The DPFE is connected by two pipes/ports on the exhaust feed pipe leading to the EGR. This sensor measures the pressure difference (differential) in the two pipes when the EGR is open; the more open the EGR the more the pressure imbalance detected by the DPFE. If the pipes/ports to the DPFE become clogged or the sensor malfunctions, the signal to the ECU will be seen as incorrect as compared to how much the EGR has opened...'insufficient air flow'. It is just as likely for the DPFE to fail as the EGR when there are 'EGR problems' . Hope this gives you another thing to check

Sep 21, 2011 | 1996 Geo Prizm

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