Obd code 401 - 1999 Mitsubishi Eclipse

oh yes i know its you EGR valve (Exhaust Gas Recalculation)

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 Related EGR Articles: P0400 - P0402 - P0403 - EGR System Explained

Read more at: http://www.obd-codes.com/p0401
Copyright OBD-Codes.com

Code 401 is for a problem with the EGR valve.
Code 449 is for a problem with the vent valve solenoid for the gas tank venting system or EVAP.
You would need a shop manual to get the test procedures for each code.

You would need the flow chart for the code as it pertains to Chrysler products.
Code 401 means the computer is getting a low flow signal from the EGR valve sensor. The flow could in fact be low due to the EGR not opening, or the sensor could be faulty.

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.

http://www.obd-codes.com/trouble_codes/ here features your problem codes. 401 is an EGR or exhaust gas recirculation problem. saying exhaust gas is not getting back to the intake. this is almost a non issue. its there purely to help reduce emissions by your vehicle and a by product is actually more heat being shunted back to the motor and less power as bad gas gets mixed with good oxygen. the other is an oxygen sensor malfunction. this is concerning as the computer may be telling the engine to "Lean out" the fuel. pushing less fuel into half or all of the engines cylinders and when it burns it burns much hotter than a "rich" mixture. head to this link and start checking your engine for loose, cracked or damaged little black hoses called vacuum lines. http://www.obd-codes.com/p0171 that is likely why your engine cooked. the mechanic may have spilt oil onto the sensor too.

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

for info on the P0401:
http://www.obd-codes.com/p0401

PO-401
EGR Flow Insufficient Detected

code P401 is exhaust gas recirculation-insufficient flow detected.

This is an airflow problem. Usually thought to be a EGR valve problem but the problem is the sensor not the valve. With OBD 2 you should have a DPFE sensor. (Delta Pressure Feedback EGR) that is a silver box with 2 hoses coming off the bottom that connect to the egr tube. That is the problem. Replace the sensor and your P0401 (that is the correct way to write the code as the P stands for Powertrain) will go away. The new updated DPFE sensor will be plastic and will probably require an updated connector. The connector should come with the updated sensor. And please use Ford Sensors.
Thank you for using FixYa - a FiXyA rating is appreciated!!

Hi, since the check engine light (CEL) is on you need to get the trouble codes read. Most auto parts stores will do this for free. If there isn't one nearby, any shop should be able to read it (for a charge) or you could buy your own code reader.

The code(s) you'll get will be in the format PXXXX like P0171 or similar. Once you have the codes you can look them up here to get a description - http://www.obd-codes.com/trouble_codes/

Or post the codes back here and we'll help you out. The next step is to get those codes though so you know exactly which areas of the engine to concentrate your diagnosis efforts on. Good luck!