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P0401 after O2 sensor replacement

Tiny
STXHAMMER
  • MEMBER
  • 2002 FORD EXPLORER
  • 4.0L
  • 6 CYL
  • AUTOMATIC
  • 166,000 MILES
Hello, I recently replaced by driver side bank 2 o2 sensor. Now I am showing P0401 code. Also upon acceleration there’s a whining sound almost like a super charger sound. Is it the EGR? Or a loose hose? I have picked up some carbon cleaner also and plan on doing that also. I will be back home this weekend to search for a vacuum leak if it’s that. Thank you in advance.
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Friday, December 14th, 2018 AT 11:42 PM

11 Replies

Tiny
ASEMASTER6371
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Good morning,

The 401 code is for the DPFE sensor. It is n exhaust back pressure sensor.

Was there a code prior to this that made you think the sensor was bad?

Roy

401 possible issues

P0401
Descriptor
Egr Flow Insufficient Detected
Probable Causes
Differential Pressure Feedback EGR (DPFE) Sensor Downstream Hose Off or Plugged
Differential Pressure Feedback EGR (DPFE) Sensor Hoses Both Off
Differential Pressure Feedback EGR (DPFE) Sensor Hoses Reversed
EGR Vacuum Regulator (EGRVR) Circuit Shorted to Power
EGR Vacuum Regulator (EGRVR) Solenoid Damaged
EGR Vacuum Regulator (EGRVR) solenoid Circuit Open to Powertrain Control Module (PCM)
Exhaust Gas Recirculation (EGR) Flow Restricted
Exhaust Gas Recirculation (EGR) Orifice Tube Damaged
Exhaust Gas Recirculation (EGR) Solenoid
Exhaust Gas Recirculation (EGR) Valve
Exhaust Gas Recirculation (EGR) Valve Leak Vacuum
Exhaust Gas Recirculation (EGR) Valve Stuck Closed
Powertrain Control Module (PCM)
Powertrain Control Module (PCM) Damaged
Reference Voltage from Powertrain Control Module (PCM) Open to Differential Pressure Feedback EGR (DPFE) Sensor
Vacuum Supply
Voltage Power Open to EGR Vacuum Regulator (EGRVR) Solenoid
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Saturday, December 15th, 2018 AT 7:55 AM
Tiny
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If you’re talking about the o2 sensor, it had the P0156 code.
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Saturday, December 15th, 2018 AT 8:41 AM
Tiny
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Okay, did you do any of these checks or just replace the sensor?

Roy

P0156
Descriptor
Ho2S Sensor Circuit Malfunction (Ho2S-22)
Probable Causes
Exhaust Leaks
Sensor Contaminated or Damaged
Sensor Wires Crossed
Wiring and Pins Pinched, Shorted, or Corroded
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Saturday, December 15th, 2018 AT 8:45 AM
Tiny
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Replaced it. The wiring was melted.
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Saturday, December 15th, 2018 AT 11:43 AM
Tiny
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Good. I would replace the DPFE sensor.
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Saturday, December 15th, 2018 AT 2:06 PM
Tiny
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Would you happen to have the location of it. Passenger side of the motor I assume. And plug and play?
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Saturday, December 15th, 2018 AT 2:40 PM
Tiny
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It is on top of the motor behind the throttle body. It has two rubber hoses that go to the exhaust manifold.

It is a plug and play replacement.

Roy
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Saturday, December 15th, 2018 AT 5:26 PM
Tiny
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It seems my DPFE sensor is stuck on there. May try some wd40 on the hoses. Is that safe or no?
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Wednesday, December 19th, 2018 AT 1:12 PM
Tiny
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Yes, you can but if you damage them, replace them. They are special hoses due to the heat from the exhaust.

Roy
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Wednesday, December 19th, 2018 AT 1:22 PM
Tiny
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Okay, thanks. I’ll try without it again tomorrow. Thanks
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Wednesday, December 19th, 2018 AT 1:59 PM
Tiny
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You are welcome.

We are always glad to help.

Roy
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Wednesday, December 19th, 2018 AT 2:00 PM

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