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P0401 - Exhaust Gas Recirculation Flow Insufficient Detected
- Harness or connectors (EGR volume control valve circuit is open or shorted.) - EGR volume control valve stuck closed - EGR volume control solenoid valve - Dead (Weak) battery - EGR passage clogged - Exhaust gas leaks
- Clean EGR Valve - Repair EGR harness or connector - Replaced EGR volume control solenoid valve - Replaced EGR volume control valve
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.
problems are consistent with an egr problem before replacing try to clean carbon and free valve --remove egr and with a carb or brake cleaner clean the carbon the most common problem is carbon build up causing the valve to malfunction continue to drive can cause a full break down with the vehicle not starting or stalling while driving
EGR system malfunction. Check EGR circuit/switches. Check/replace EGR vacuum hoses. Check/replace EGR Vacuum Modulator. Remove and clean EGR valve. Test EGR valve by applying vacuum to open. If necessary, replace.
You have two options to fix this error code. One, obviously, you can replace the EGR valve. If you do this, just reset the codes and you should be good to go. Two, you can remove the EGR valve and clean the carbon build up out of it. You can do this with throttle body cleaner and just make sure to let it dry out before you put it back on. You need to make sure that the valve (diaphram) is moving freely after you clean it. If it isn't, you are going to need to replace the EGR valve. Let me know if you have any further questions. Thanks for rating my response and for using FixYa!
If it is not just badly clogged, the intake does not need to be cleaned out. If you want to clean it out then take some brake cleaner and spray it in there and wipe it with a rag. I have never seen someone have to clean the intake due to not being clogged. Just my expierence I would just change the EGR and go from there
EGR flow is monitored by the PCM by it looking for a reaction in the FRONT O2 sensor in responce to the command given to the EGR valve. The linear electronic EGR valve sends a return signal to the PCM indicating the relative position of the step motor and hence how far open (or closed) the EGR valve is in responce to the PCM command. The PCM expects to see (within a set of given parameters) a change in the O2 sensor reading (change in exhaust gas make up) after the EGR valve is commanded open or closed. If it doesn't, or that change is not within the expected parameters, a code will be set based on the skewed data. Generally a "insufficient flow" code will be set by:
1.Faulty EGR valve (sticking, or "lying" to the PCM about the actual valve position) 2.Faulty electrical connection at the EGR valve (causing false data) 3.Clogged EGR passages 4. Bad read from the MAP, or TPS, causing the PCM to misinterpret the EGR data based on faulty operational data from the other sensors 5. (Very rarely) A marginally "slow" O2 sensor. (PCM does not "see" the change in exhaust make up quick enough and interprets that as poor EGR flow.)I have found that normally this code means that the EGR is not opening the amount that it has been commaneded to by the PCM. Normal cure for me lately has beed to repalce the EGR valve and to clean out the passages while the valve is off. The Tech 2 is able to command the EGR open and show the commanded opening and the actual opening. When this code is present the actual and commanded do not match closely at all.Thanks for using FixYa - a FixYa rating is appreciated for taking the time to answer your FREE question.
-after you change the part you have to reset/clear the code
-this can be done by either:
(1) using the OBD2 code reader that Autozone used OR since option 2 (below) is very quick
(2) disconnecting the battery for about 30 seconds (this will delete
all codes/radio presets/etc) but it will also clear the 'check engine'
-this is what I do AFTER i write down my radio station presets :)
-hopefully the new EGR valve resolves your issue after you CLEAR the code
...but that code just means a an insufficient amount of Exhaust Gas
recirculation (pressure difference) used to keep the emissions in check
-if it comes back, then there are a few other fixes to try also
-let me know if you need further assistance
-please remember to rate me `fix-ya`if it works