1998f1504.6wtriton runs fine but getting codes 401,171and174check all vacum lines,dpfe sensor,sprayed carb cleaner everywhere,new egr ,egr tube,took off elbow and throttle body cleaned it up no blockage ,checkedpcv and vacum lines clear,took off maf cleaned it ,cranks up runs fine light is bugging me.

P0401 OBD-II Trouble Code - Insufficient EGR Flow

What does that mean?
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.

Symptoms
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.

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

Re-Check the possible solutions and tell us news (remember rated this).

Does the egr vavle open ? You will need to use a scanner to test the dpfe voltage when the egr valve is energized you should read around 3.5 4.00 volts. Also you could remove the vacume line from the egr valve and with the engine running you should see around 100 rpm drop in engine rpm at least this would indicate the egr valve is capable of flowing egr gases through the system to the cylinders.

Technical Description

Insufficient EGR Flow

What does that mean?

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.
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

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 noticeable 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)

EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emissions 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.

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 vacuum

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 noticeable 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

Check for

vacuum leaks on intake manifold,

the air tube between the air filter.

intake manifold vacuum hose.

===
clean throttle plate with Berryman carburator cleaner

SEE sample picture HERE
===

Also remove carbon built up behind the EGR valve and the EGR passage tube.

===

Vacuum leak WILL offset the intended 14.7 to 1 air fuel ratio.

More un-metered air (leaks) will lean out the fuel mixture.

Use small amount of Berryman carb clearer at potential air leak area will help you identify trouble spot.

At idle,just spray and listen for the RPM surge.

The in-rush of carb clearer will increase the RPM on the motor.

Record the problem spot(s) and address it later.

===

EGR carbon built up require 2+ hours to clean from start to finish.

You will need a new EGR base gasket before your start.

Locate and remove the EGR valve after the vehicle is cool down.

Carefully record the connector and vacuum line (for older vehicle) location by drawing an easily to follow diagram.

Remove the EGR valve.

Inspect the location of the carbon built-up inside the valve and the EGR passage tube.

SOAK these areas with WD-40 spary.

You will need a small screwdriver,cloth hanger and lot of newspaper and time to get this cleaning done right.

RE-SOAK the carbon and let it sit for over-night will also help.

One the last round,pass a shop vacuum of the EGR valve and the passage pipe.

Install the new EGR gasket and connectors.

Allow the vehicle to warm up outdoor to burn up any remaining WD-40.


Take it for a test drive.


Please rate my answer if it's useful to you.


Cheers,

Mustgo

Check for

vacuum leaks on intake manifold,

the air tube between the air filter.

intake manifold vacuum hose.

===
clean throttle plate with Berryman carburator cleaner

SEE sample picture HERE
===

Also remove carbon built up behind the EGR valve and the EGR passage tube.

===

Vacuum leak WILL offset the intended 14.7 to 1 air fuel ratio.

More un-metered air (leaks) will lean out the fuel mixture.

Use small amount of Berryman carb clearer at potential air leak area will help you identify trouble spot.

At idle,just spray and listen for the RPM surge.

The in-rush of carb clearer will increase the RPM on the motor.

Record the problem spot(s) and address it later.

===

EGR carbon built up require 2+ hours to clean from start to finish.

You will need a new EGR base gasket before your start.

Locate and remove the EGR valve after the vehicle is cool down.

Carefully record the connector and vacuum line (for older vehicle) location by drawing an easily to follow diagram.

Remove the EGR valve.

Inspect the location of the carbon built-up inside the valve and the EGR passage tube.

SOAK these areas with WD-40 spary.

You will need a small screwdriver,cloth hanger and lot of newspaper and time to get this cleaning done right.

RE-SOAK the carbon and let it sit for over-night will also help.

One the last round,pass a shop vacuum of the EGR valve and the passage pipe.

Install the new EGR gasket and connectors.

Allow the vehicle to warm up outdoor to burn up any remaining WD-40.


Take it for a test drive.


Please rate my answer if it's useful to you.


Cheers,

Mustgo

Code P1401 Is (DPFE Curcuit High Input )Its Part Of The EGR System It Tells The EGR Valve What To Do The DPFE Stands For (Delta Pressure Feedback EGR Sensor) It Messures Pressure In The EGR System And Tell The ECM Weither To Open Or Close The EGR Valve

1. Have tried cleaning out the throttle body? Carb cleaner and a rag should do the trick. Also, try bypassing the vacuum solenoid. First, remove the vacuum line from the solenoid, start the car, and then connect the vacuum line directly to the EGR valve. The car should run very rough and die. If not, then there is still something blocking the system (since you replaced everything, it might be down in the pipe (between valve and exhaust)). Also, ensure that the vacuum is strong enough by ensuring that the lines sticks to your fingers. Final possibility is that your new sensor is bad. You can do a voltage check (with igntion turned toon: 1 wire at 5 volts, 1 wire at 0 volts and 1 wire at about .5 tp 1.1 volts). The aftermarket sensors are not always of the best quality.
   

P1400 on your vehicle is described as :Differential Pressure Feedback EGR Circuit Low Input You either need a new DPFE valve, or a new EGR valve. Both can be tested for functionality before replacing them both. EGR valve is more likely I think. Cleaning it may not improve its performance, but its worth a try. Also check the vacuum lines between the DPFE and EGR system. The EGR valve and DPFE are usually close together above the exhaust manifold/downpipe. you need service instructions to test these items, suggest you go to a garage really...