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OBD-Codes.comhttps://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.
Po401 egr system circuit problem Most problems occur with the back pressure transducer the hose on the under side goes bad also but some times it is the control solenoid under the intake manifold that goes bad during decel the valve nust close to see if flow is detected into intake if not the Check engine light will come on 2 trip detection .
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).
but for convenience I have reproduced that information here: . Generic OBD Error Code Details for P0401Exhaust 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
Trouble codes are normaly 4 digits with a "P" or "B" before it. I am gonna assume that you meant P0138 and P0401:
P0138 is Oxygen Sensor Circuit High Voltage (Bank 1, Sensor 2) P0401 is Exhaust Gas Recirculation Flow Insufficient Detected
A code P0138 may mean that one or more of the following has happened:
Faulty O2 sensor
Short to battery voltage in O2 sensor signal circuit
High fuel pressure (not as likely)
Possible Solutions
Here are some potential solutions:
Replace O2 sensor
Repair short to battery voltage in o2 sensor signal circuit
Based on what the tech manuals say I would change the DPFE sensor for the EGR Valve, careful not to tear the special silicone rubber hoses that go to it from the exhaust, as a Ford dealer tech I saw these codes allot, and the DPFE sensor was almost always the issue or the hoses going to it.
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