Question about 1996 Lexus LX 450

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Code on diagnostics p0401

Said gas recirculation insuffent flow. what needs to be done?

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Code on diagnostics p0401:

What is going on?
Exhaust Gas recirculation low flow detected means that: there is vacuum problem in the EGR system - between the combustion chamber, EGR valve (mechanical - blown up diaphragm or clogged airlets/hoses) , EGR Modulator Valve (mechanical - blown up diaphragm, dirty EG/air filter or clogged airlets/hoses) and Vacuum Switching Valve ((mechanical - blown up diaphragm or clogged airlets/hoses OR electrical - VSV not properly synchronizing with the ECM, for instance).

Effects?
This causes the combustion chamber temperature to increase and produce Oxides of Nitrate (NOx) that is out of an acceptable emission range. This triggers the Malfunction Light (check engine light) to stay on (after a couple of driving cycles)!
Solution: Focus on EGR airways (hoses...) and organs (EGR valve, EGR Modulator, VSV), clean, check or replace the defected one. VSV seems to be criticale as it plays electrical & mechanical function. Once the repair is done, Clear the P0401 code using an OBII scanner.

Posted on Jun 16, 2009

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Most common problem with Lx 450 EGR is EGR vsv. & then EGR modgulator Lexus & Toyota EGR systems rarely get plugged

Posted on Feb 03, 2009

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Clean out the e.g.r valve its blocked up,not familiar with lexus but the chances are it might need reseting after,most vw's do.

Posted on Dec 21, 2008

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What do OBDII Codes P0401 and P0404 indicate in a 2001 Chevy Impala?


P0401 usually means for most vehicles
Exhaust Gas Recirculation Flow Insufficient Detected

P0404 usually means for most vehicles
Exhaust Gas Recirculation Circuit Range/Performance


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What do the OBDII trouble codes P0401 & P0404 mean with 2001 Chevy Impala?


P0401 Exhaust Gas Recirculation Flow Insufficient Detected

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Fault code p0401


Most probably the EGR (Exhaust Gas Recirculation system) is full of gunk, generated by the exhaust gas and breeder fumes and needs to be cleaned. Though it might be some other system that triggers this error. You could do the following to see if it can be remedied.
  • Check/Clean Exhaust Gas Recirculation (EGR) System
  • Check/Replace Exhaust Gas Recirculation (EGR) Valve
  • Check Wiring and/or Connector(s) from/to Exhaust Gas Recirculation (EGR) Valve
It is likely this cannot be fixed easily and needs a full diagnostics and system cleanup at the Dealer/Skoda authorized service center. Might cost a lot since you probably need to remove the intake manifold, etc. to get the system cleaned properly.
You can read more about the code and the issue at ross-tech:
16785 P0401 001025

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Trouble code P0401


code p0401 refers to exhaust gas recirculation(EGR) system-insufficient flow detected--- Causes ---hose leak/blockage, basic setting not carried out( if applicable)wiring--EGR valve/solenoid---ECM I would check the EGR valve solenoid first. Replace the faulty units with genuine one because most aftermarket units are not set for OEM cpu units and are not completely
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May 11, 2013 | 1997 GMC Sonoma

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Trouble code P0401


P0401 Exhaust Gas Recirculation Flow Insufficient Detected
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Check engine light code P0401 98 Ford expedition


OBD-II Trouble Code P0401 - Insufficient EGR Flow

EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR. You may notice drivability problems such as pinging (a.k.a. pre-ignition knock) when the engine is under load or the vehicle is at higher speeds. There may also be other symptoms.

A code P0401 most likely means one or more of the following has happened:
The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
There is a blockage in the EGR (tube), most likely carbon buildup
The EGR valve is faulty
The EGR valve may not be opening due to a lack of vaccuum

Check it and keep us updated. Hope this helps (remember to rating this free answer).

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Fault code p0401


This error means Exhaust Gas Recirculation Flow Insufficient Detected.

You can deatils on the following site http://www.permoveo.ltd.uk/tabid/122/OBD-Error-Code/P0401/Diagnostics/Hyundai/Default.aspx

but for convenience I have reproduced that information here:
.
Generic OBD Error Code Details for P0401 Exhaust Gas Recirculation Flow Insufficient Detected What does this mean? OBD Code P0401refers to
EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR. SymptomsPossible sumptoms of OBD code P0401
You may notice drivability problems such as pinging (a.k.a. pre-ignition knock) when the engine is under load or the vehicle is at higher speeds. There may also be other symptoms. CausesPossible causes of OBD code P0401
A code P0401 most likely means one or more of the following has happened: •The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced•There is a blockage in the EGR (tube), most likely carbon buildup •The EGR valve is faulty •The EGR valve may not be opening due to a lack of vaccuum Possible SolutionsIn fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit. •Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's & DPFE voltage. There should be a noticable difference in RPM's with the EGR open •Clean out the EGR valve and/or tubing to remove deposits•Check the voltage at the DPFE, compare to specified values (refer to a repair manual for your specific model)•Replace the DPFE sensor (with a good quality / OEM one)•Replace the EGR valve Related CodesP0400 P0402 P0403

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I have 4 codes: 1- p0401 2- p0401 Pd 3- p0403 4- p0405 what do I have to do to get rid of these codes. what are these and where are they located on a 2004 grand am Thx


p0401
Exhaust gas recirculation-insufficient flow detected
p0403
Exhaust gas recirculation-circuit malfunction
p0405
Exhaust gas recirculation vave position sensor A- circuit low

hope this helps. not sure where they are located

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The DPFE sensor has failed on you egr system .Replace just this part and don't let someone sell you a egr valve .The sensor is about$70 and faily easy to do .:)

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