2001 Isuzu Trooper Logo
Posted on Dec 17, 2009
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Have a code p0401 how do u fix it , I know it has something to do with the egr system but I,m not sure where its located on my trooper, engine size is 3.5 v6

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  • Posted on Jun 14, 2012
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I have a 2000 Isuzu Trooper that had a PO401 code that would reset and then 2 miles later the light was on again - I found if you remove the EGR valve and start the engine that the engine should idle rough - If it doesnt and you have vacumn at the intake port spray carb cleaner down the port slowly and see how long it takes for the engine to run rough - Keep spraying till the engine dies and spray some more down the passage and let the engine set for 5 minutes and then restart the engine - it will run rough at first but clear out - you should be able to feel the engine RPM change when you put your finger over the intake vaccumn port for the egr - If not then repeat the cleaning method again - If you do feel the rpm change then put the egr valve back on and clear the code and run your drive cycle to see if it is fixed.

  • Anonymous Jun 14, 2012

    I have a 2000 Isuzu Trooper that had a PO401 code that would reset and then 2 miles later the light was on again - I found if you remove the EGR valve and start the engine that the engine should idle rough - If it doesnt and you have vacumn at the intake port spray carb cleaner down the port slowly and see how long it takes for the engine to run rough - Keep spraying till the engine dies and spray some more down the passage and let the engine set for 5 minutes and then restart the engine - it will run rough at first but clear out - you should be able to feel the engine RPM change when you put your finger over the intake vaccumn port for the egr - If not then repeat the cleaning method again - If you do feel the rpm change then put the egr valve back on and clear the code and run your drive cycle to see if it is fixed.

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  • Posted on Dec 17, 2009
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It may be a bad EGR valve or it may just have carbon buildup. It can also be carbon buildup in the intake. If your Trooper is hard to start, idles poorly, and runs rough the EGR valve is more than likely bad. If you are not experiencing these symptoms then it is probably just dirty.

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What are codes p0401 and p0300 mean on a 2000 isuzu trooper

P0401 is EGR problem
P0300 is a cylinder 3 misfire.
Replace EGR valve and do a full tune-up.
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Egr vacuum solenoid location

what type of toyota u have or if u can give me the engine code i might b able to help u
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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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1996 Trooper (P0401 Code- GONE!!!-) BUT,,,,now I have Code- P1133 and P1153. Both are O2 sensor codes. Here is the weird thing! I tried everything in the book to try and fix the P-0401- Insufficient...

I had a similar problem with code PO401
The solution was to loosen up the throttle cable a bit.
Since the TPS value has to be at 0.0% at idle.
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OBD Codes P0401; P0171; P0174. EGER valve sensor vacuum tube winds up upon starting; will not idle. What have others found to be the issue? EGR sensor has gotten very hot and plastic tube connectors have...

p0401 egr flow insufficient. p0171 system to lean ( bank 1 ). p0174 system to lean ( bank 2 ). common problems that trigger p0401--
  • Restriction in the EGR passages, usually caused by carbon buildup
  • The EGR Valve is defective
  • Lack of proper vacuum or electrical signal to the EGR valve
  • Malfunctioning EGR Vacuum supply solenoid
  • Lack of proper EGR system feedback to the computer from the:
    • Manifold Absolute Pressure Sensor (MAP)
    • Differential EGR Pressure Feedback Sensor (DPFE)
    • EGR Valve Position Sensor (EVP)
    • EGR Temperature Sensor - p0174--
    • In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling also
    • Inspect all vacuum and PCV hoses, replace if necessary
    • Check for a dirty fuel filter and proper fuel pressure p0171- and p0174 are about the same.
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How do I clean the EGR PIPE in this 1996 Trooper? I have a P0401 code, have replaced the EGR valve, put a cleaner thru the system via the air intake, put a cleaner in the gas and still the P0401 code. I...

It should just unbolt. The problem is those tend to get frozen to the exhaust manifold, especially the higher mileage ones. Once you get it of, let it set in carb cleaner for awhile. If you have a flexable wire gun stock type brush, this will help aid you in this. You might even try a local machine shop for the carb solvent if you do not have any.
1helpful
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2002 Mercury cugar P0401 and P1401

DTC 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.

Causes: 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 Solutions: In 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


DTC P1401 - Differential Pressure Feedback Electronic Sensor circuit High Voltage

I think that you need a new DPFE; first check it, you could also have something restricted. There are ports in the throttle body that can cause this as well. Check THIS LINK.

Hope helps.
4helpful
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2000 isuzu trooper: OBD-II Trouble Code: P0401 Insufficient EGR F

Your SUV is really giving you a hard time, lol. Sorry but I've had those days too.
I would try to check if you have blocked EGR passages. If ok check for restricted MAP sensor vacuum hose/passage or restricted exhaust. I know you replaced the CAT but if the muffler is blocked then there would still be a restriction. Also check the wiring and connection to the MAP sensor.
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My check engine light and TCS light came on. Code

P0401: Isufficient Flow Detected in EGR system.
-clean the EGR port with the carburetor cleaner.
-clean the EGR passage inside the EGR valve with the caburetor cleaner.
Reset the light, if the light still coming back, then replace the EGR valve.
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