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Fault code P0401, have replaced cracked tailpipe, EGR valve, EGR vacuum solenoid, reset and still engine light comes on after 10 miles! Won't pass inspection can anyone help

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Posted on Jul 30, 2013


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Posted on Jan 02, 2017

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SOURCE: 2000 Honda Accord EGR Valve Error P0401

-after you change the part you have to reset/clear the code

-this can be done by either:
(1) using the OBD2 code reader that Autozone used OR since option 2 (below) is very quick
(2) disconnecting the battery for about 30 seconds (this will delete all codes/radio presets/etc) but it will also clear the 'check engine' code
-this is what I do AFTER i write down my radio station presets :)

-hopefully the new EGR valve resolves your issue after you CLEAR the code
...but that code just means a an insufficient amount of Exhaust Gas recirculation (pressure difference) used to keep the emissions in check
-if it comes back, then there are a few other fixes to try also

-let me know if you need further assistance
-please remember to rate me `fix-ya`if it works

Posted on Nov 03, 2008

  • 4669 Answers

SOURCE: exhaust recircuulation flow insufficient detected-p0401.

Can you give me a code number. Also the egr ports plug in the elbow the valve is bolted to. Remove the elbow and clean the ports.

Posted on Mar 15, 2009

  • 202 Answers

SOURCE: P0401 Exhaust Gas Recirculation Flow Insufficient

check the metal line that comes off the exhaust and make sure it isnt plugged with carbon. also remove the egr and check the port and see it's clogged as well

Posted on Nov 17, 2009

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P0401 indicates that the Exhaust Gas Recirculation Flow Insufficient Detected. This can be because EGR is faulty . As you have replaced this then the problem must be with the vacuum line . EGR valve vacuum line which can be broken or blocked. The vacumn ine must bbe checked for leaks or any blocks using an vacumn pump connected the line.

P0420 indicates that the down stream oxygen sensor reading is not steady and it is connected with the code P0401.

Posted on Jan 05, 2011

  • 1165 Answers

SOURCE: ive got a 98 chevy lumina with a p0401 code ive

Did you have the engine scanned, or did you do it yourself? The reason I ask is, the code would need to be cleared after the new egr valve was installed. You would need to do another scan, and then clear the code with the scanner tool. If you tried to clear the light by removing power from the ECM, that would only clear the light from the dash temporarily. The code would still be present in the ECM memory which would cause the light to reappear.

Posted on Mar 09, 2011

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It shows code P0401. Already replaced the EGR valve and catalytic converter plus sensors. What now.

You didn't say if you have any symptoms so I will assume you don't. After you made the repairs, you have to have the code removed. Any major auto parts store will do it for free. If the code don't come back, its fixed.

Mar 23, 2015 | 2001 Hyundai Santa Fe

2 Answers

P0401 error code

Depending on your Year and Model, there are some more prone to this Code than others because of the material used in the intake manifold. Ford and its affiliates switched from Aluminum to Plastic to prevent sooting.

On the old style 4.6L a passage under the Airhorn would clog and prevent EGR flow. Bad EGR flow is a Code 401. It can be a Solenoid valve failing to open, but many times it is a clogged passage as I mentioned. Sometimes a bad EGR has a ruptured diaphragm which can be checked by drawing the Vacuum out of it.

For those engines a simple $10 gasket and removal of 8 screws will allow you to scrape out the valley the passage is in.

So this fix is not real expensive, get parts at common autoparts stores.

Apr 06, 2013 | Ford F-150 Cars & Trucks

1 Answer

1996 toyota corolla p0401

code p 0401 refers to exhaust gas recirculation (EGR) system--insufficient flow detected ===causes --hose leak/ blockage--basic setting not carried out if applicable ---wiring---EGR valve ---EGR solenoid --ECM
take it to an accredited service centre that has experience on your make of vehicle , tell them the fault details and get a proper diagnosis to determine the fault and a quote

Mar 27, 2017 | Toyota Corolla Cars & Trucks

1 Answer

Ford e150 codes: p0401, p1401 and p0174. read the more details to see what the symptoms are.

Stop, DO NOT replace expensive parts or O2 sensor! Ford Explorer codes p0174 , p0401 , rough idle and check engine light on. First thoroughly check all of the hoses and elbows connected to the intake and EGR (vacuum system) for splits, cracks, holes or tears, this could quickly cause these codes and fixes for less than $10. Check all connectors and the EGR valve sensor it could have a crack as well, inspect thoroughly because a split sensor could appear attached to the vacuum hoses but hoses could just be sitting there not actually attached due to a split or crack. This was my problem replaced the EGR valve sensor and the two little vacuum hoses attached to them for $50-60 with in stock parts at the local parts store. Took less than 10 minutes to replace and is easily accessible, the check engine light turned off immediately without having to reset the codes by disconnecting the battery, idle became normal and fuel efficiency better. If you have THOROUGHLY inspected every hose, connector and elbow and found no issues, clean the MAF with electrical contact cleaner ( let dry) and clean the EGR with carbon cleaner. A dirty MAF or EGR could also cause these codes to pop up. If this still doesn't work, then consider replacing the EGR, if that isn't it then try the O2 sensor. Good luck!

Jun 23, 2012 | 2002 Ford E-Series

2 Answers

Have 1999 Mercury Sable and failed emissions for P0401 code, I replaced the EGR Valve and had the code reset, service engine light came on again Approx 15 miles later. Took it to Auto Zone and they gave...

I am not surprized. The chances that replacing an EGR valve will fix a code P0401 on ANY Ford vehicle is about 1/2 of 1 percent. You most likely either have clogged up EGR ports in your intake manifold, or you have a defective Delta Pressure Feedback EGR (DPFE) sensor.

To find out which it is, apply vacuum to the EGR valve vacuum port with the engine idling. The engine should stumble and/or stall. If it does not, your ports are clogged. If it does, the most likely cause of your problem is the DPFE sensor. However, the EGR vacuum control solenoid could also be the cause.
You cannot properly test the EGR vacuum control solenoid without the proper equipment, but you can check to make sure that there is manifold vacuum going into one side of the solenoid and you can check to make sure that there are no breaks or leaks in the line that runs between the solenoid and the valve. If you find any of these, repair as necessary. If you do not find a problem with the vacuum lines, then you can take a "guess" and replace the DPFE. If this does not work, then you can "guess" again and replace the solenoid. If it still does nort work, then you probably have a bad electrical circuit to the solenoid (once again, requiring the proper equipment to diagnose).

Please also review the following article: What Else Could Be Wrong?

Nov 18, 2011 | 1999 Mercury Sable

1 Answer

Check engine light stays on the code that keeps coming up is P0401 changed egr valve clened out carbon build up also smell gas when first start not driving and fuel millage not as good car runs good though...

Could be a EGR vacuum issue or temp sensor issue

Common Problems That Trigger the P0401 Code
  • Restriction in the EGR passages, usually caused by carbon buildup
  • Lack of a proper vacuum signal to the EGR Valve from EGR Vacuum Solenoid
  • EGR Vacuum Modulator is defective
  • EGR Temperature Sensor is defective
  • EGR Valve is defective
This is from:

Jan 31, 2011 | 1998 Chevrolet Lumina

1 Answer


P0401 indicates that the Exhaust Gas Recirculation Flow Insufficient Detected. This can be because EGR is faulty . As you have replaced this then the problem must be with the vacuum line . EGR valve vacuum line which can be broken or blocked. The vacumn ine must bbe checked for leaks or any blocks using an vacumn pump connected the line.

P0420 indicates that the down stream oxygen sensor reading is not steady and it is connected with the code P0401.

Jan 05, 2011 | 2001 Toyota Camry

1 Answer

I just bought a 1997 Mercury Sable it was a private sale. Once I got it home the check engine light was on can't remember the code but it when I looked it up it was the canister purge valve. Spent $80. for...

P0401 insufficient EGR flow.

Possible causes:
  • Fault in vacuum supply to EGR vacuum regulator solenoid.
  • EGR valve stuck closed or iced.
  • EGR valve diaphragm leaks.
  • EGR valve or flow path restricted.
  • EGR vacuum hose off, plugged or leaks.
  • VPWR circuit open to EGR Vacuum Regulator solenoid.
  • EVR circuit to PCM open.
  • EVR circuit to PCM shorted to PWR.
  • Differential Pressure Feedback EGR (D.P.F. EGR) sensor pressure hoses both connected improperly.
  • D.P.F. EGR sensor pressure hoses reversed.
  • D.P.F. EGR sensor VREF circuit open.
  • Downstream pressure hose off.
  • Downstream pressure hose plugged.
  • Damaged orifice tube assembly.
  • Damaged EGR Vacuum Regulator solenoid.
  • Damaged D.P.F. EGR sensor.
  • Damaged PCM.

P0443 indicates an intermittent EVAP canister purge valve circuit failure.
Possible causes:
  • Intermittent EVAP canister purge valve or VPWR circuit open.
  • Damaged EVAP canister purge valve.

Mar 13, 2009 | 1997 Mercury Sable

1 Answer

97 tracer P0401 code won't go away

Late suggestion; it may be that the code needs to be reset via a code reader and that the problem will remain in memory until forcibly removed. That is fairly common.

Feb 22, 2009 | 1998 Mercury Tracer

1 Answer

97 tracer P0401 code won't go away

the light may have nothing to do with the previous fault
run the fault codes again

Sep 11, 2017 | 1998 Ford Expedition

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