Check engine light came on codeP0401

Hi Joe

Like all solenoid valves, you can clean them with throttle body cleaner and then test the solenoid electronically with a 12 volt supply.

P0401 Exhaust EGR Flow Insufficient

Toyota Nation Forum https://www.toyotanation.com > threads > p0401-exha...
May 1, 2014 - The sensor is how the ECM determines there's insufficient EGR flow. It's on the intake-side of the system and if not enough exhaust-gases flow ...

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P0401 : EGR Flow Insufficient on 1996 Toyota Corolla

OBD-Codes.com https://www.obd-codes.com > forums > viewtopic
Jan 20, 2007 - on EGR codes, we recommend replacing the EGR, vacuum modulator and VSV (if equipped) and cleaning out the carbon buildup to the intake from the ...
If that finds nothing wrong, remove the EGR valve and bypass tube and check them for cleanliness and blockages. If they are blocked, follow your maintenance manual's instructions for cleaning them out so you do not damage the valve, then replace them and reset the ECM.

Insufficient EGR Flow - P0401 Code - Toyota

That's not what this code is about .P0401 - EGR Flow Insufficient Detected . Probably clogged egr passages .
P0401 - EGR Flow Insufficient Detected The EGR system is monitored during steady state driving conditions while the EGR is commanded on. The test fails when the signal from the DPF EGR sensor indicates that EGR flow is less than the desired minimum.

• Vacuum supply
• EGR valve stuck closed
• EGR valve leaks vacuum
• EGR flow path restricted
• EGRVR circuit shorted to PWR
• VREF open to D.P.F. EGR sensor
• D.P.F. EGR sensor downstream hose off or plugged
• EGRVR circuit open to PCM
• VPWR open to EGRVR solenoid
• D.P.F. EGR sensor hoses both off
• D.P.F. EGR sensor hoses reversed
• Damaged EGR orifice tube
• Damaged EGRVR solenoid
• Damaged PCM

Perform KOER self-test and look for DTC P1408 as an indication of a hard fault. If P1408 is not present, look for contamination, restrictions, leaks, and intermittents.

wow I wish ford could make a egr system that wouldn't fail as I've seen this one go a lot lately ! anyways the code is for insufficient flow in the egr system , this is a means to recirculate some of your exhaust back into your intake , as a means to reburn some of your excess fuel (emissions) , anyways it consists of a means to meter some of the exhaust , and control it (off/on) also to measure the amount that goes in , its part of the closed loop of the fuel inlet system , the fault code is specifically saying flow sensor cant detect any flow in the pipe , there can be a few causes for this including a bad flow sensor , all are from my opinion a poorly designed system (it doesn't self clean it's self ) as almost a guaranty every 60k miles your gonna have some problem with it

Here's a link on your P0401 and how to repair, OBD II code P0401 Exhaust EGR Flow Insufficient

P2106 THROTTLE ACTUATOR CONTROL SYSTEM,-PO401-EGR INSUFFICIENT FLOW

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).

P0401....Exhaust Gas Recirculation Flow Insufficient Detected

best advice with the EGR valve problem is to make a gasket with a coca cola can and sel it off completely

When you replaced the EGR valve did you check the EGR passage to make sure it wasn't clogged. Since exhaust gasses flow through the EGR passage carbon builds up on the walls restricting flow which can eventually lead to the code p0401 Insufficient EGR flow.

Remove the air tube to the throttle body. Open the throttle all the way and look inside with a flash light. You are looking for a lump of carbon at the egr port int the intake manifold.

Remove the egr valve, using a hanger or stiff wire, clean out the egr port removing the carbon from the intake manifold.

it is your EGR Valve. 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

LOCATION:
drivers side of the engine bay, just under the intake manifold plenum where the throttle body bolts up! If you take the air snokel off you'll see it better! It has a remote mountted vaccum solenoid with a 2 wire connector going to it that you should be able to see near the throttle body.
Follow the hose from the solenoid down to the valve and you'll find it!

hopes this helps-------lebones