Service engine light on - code p0401 - EGR Sensor - 1999 Sable - Taurus - could be a build up of carbon Can you clean them or must they be replaced?

Answer 1

You can try cleaning it, but in general, most people have found that it needs to be replaced.

Although it is probably too late for this particular user, I recently searched and searched for an answer to the same questions about the p0401 in the late 90's Sable (Taurus)

Mine is a 3.0 24 valve Duratec. I am not sure about the process for any other models.

tools required:

• throttle body cleaner
• paper towels
• hard metal wire
• socket wrench and a 5/16, and a 10 millimeter deep well
• digital camera
• patience

OK: Here goes. Before you do anything else, do not buy any parts, whatsoever. Get to Autozone...buy some throttle body/air intake cleaner. Detach your negative (most likely black) battery cable (unless you owners manual suggests otherwise) Take a digital picture of how your throttle body looks before you start taking it apart. You will need to know where the various springs reattach.

Get yourself a socket wrench, with a 5/16ths, and a deep-well 10 millimeter socket. Take off your air cleaning tube, and make sure you are certain which hoses reconnect to where. once it's off, you'll see a brass plate inside the exposed hold. That is called the throttle plate. There is a lever to the left side that controls when it opens and closes, this lever is attached to a series of springs and a steel cable (the throttle cable). Take off the retention plate for the throttle cable (it will also be valuable to remove the throttle cable from its place, so that you are sure that you have not stretched it out in any way). Then, whip out that 10 mil deepwell, and take off the 3 bolts and one post screw holding the throttle body on. Yes, you are going to clean it, but that comes later, never mind that sticker on the top of the opening that says 'do not clean throttle body,' you won't hurt anything.

Take off the throttle body gasket, and do not break it, you will need it later. If it needs scraped off, take a picture of what it looked like for a reference, a discount auto parts store will try to sell you the wrong one, i promise. and that is a whole can of worms in a different story.

When you look inside the area revealed by removing the throttle body and gasket, you will see the air intake manifold. See where the egr valve is, looks like it goes into the manifold, right? No, none of those holes that are actually inside the manifold lead to it. Instead, on the face of where the throttle body mounted to the manifold, there is a c-shaped passage-way that has 3 opening that would allow air to bypass the throttle body gasket. remove the egr valve (10 mil as well) and get your piece of hard metal wire. you will have to make a 90 degree turn inside the egr passage to find where its outlet is, but, if you can't get the wire through, that is what is causing your p0401. remove that valve on the top of the air intake passage way (it's your idle air control valve, and you can't go liberally spraying throttle body cleaner into if or you will burn our the little motor at the end). in either case, whether it is completely clogged or not, place a paper towel underneath that c-shaped passage (it took me a while to figure out what people were talking about, mine was solid-black, caked completely with carbon, I didn't even realize it was supposed to be an open channel!!) completely douse it with the throttle body cleaner to break it up a little, and proceed to clean it out with your hard metal wire (a tiny, flat screwdriver might also be helpful, but be careful the cast mold of your air intake is aluminum, and will scratch very easily) repeat as necessary until it is clean, and make sure the passage is open leading to the egr valve (top left of the C).

Now you can clean out your throttle body itself. I found it easiest just to spray some cleaner in it, and let it sit. You do not want to scratch the inside of the throttle body. the cleaner, and then a good wiping with some paper towels will do the trick. Get back to Autozone, and bring the throttle body gasket (or picture of it) and order a new one, make absolutely certain that they are the same...remember, can of worms. you don't want what happens with the wrong gasket, it is unbelievably stressful to have your Mercury Sable station wagon sound like it is ready for the Indy 500.

replace all the parts, referencing the first digital pics you took to ensure it's all assembled properly.

I would suggest (although it is not necessary) to leave off the clean air tube overnight, and prop a brick on the gas pedal to open the throttle plate, it will allow all the acetone and alcohol from the throttle body cleaner in the a.i. manifold to evaporate.

Reattach the clean air tube (if you haven't already) and then reattach your neg. power cable. Start her up...and listen to that kitty purr. just kidding, for a while it will run strange, and unbelievable amounts of smoke will pour out. that's the carbon you cleaned up and the throttle body cleaner burning off. don't stress. Let it idle for a while. An extended strange idle means something went wrong, either a vacuum leak (bad gasket, you could have not reattached a hose)

If you took off you neg battery cable, you will find that your SES / CEL light has been reset and is now off. Don't be too confident, this could have only been one of your problems. Drive it for a day or 2, and see if it comes back on. if you get another p0401, then it is 75% certain to be your dpfe sensor. It's back, behind the throttle body, under the a.i. manifold, on the drivers side of the engine. You'll need that 5/16th and alot of blind groping to get it off. The new sensors are shaped differently, so you will also need to get new hoses (which is probably a good practice anyways). the 'ref' hose will need to be at least an inch longer than it was with the factory dpfe sensor.

happy times, hope this helps someone.

I'd bet you anything it has nothing to do with your egr valve. Hope you didn't waste the cash on a new one yet. Most often a new dpfe sensor does the trick. But in the Fords, depending on the engine, there is also a passageway that clogs up within your intake manifold. If your egr valve mounts onto the front of the intake on the drivers side, i would take the throttle body off and look just in case. If there is excessive carbon build-up, clean it out with some throttle body cleaner, and it might help your problem. Cheap fix, if your patience isn't considered an expense. Good luck. the dpfe sensor might run you 20-30 bucks, and a new throttle body gasket is 99 cents.

AnswerIt means the PCM sees a lack of EGR valve flow. That could be a problem with the EGR, EGR passages, EGR control system, EGR position sensor, wiring, or PCM. Answerp0401 is insufficient flow in the egr. take off your throttle body and clean out the c-shaped passage on the face of the air intake maniflod. if that fails, get a new dpfe sensor. if that fails, check all of your hoses again. If that fails......well....we're getting closer to a bad pcm here....next is the vacum (evr) then the egr vavle itself. best of luck. my 98 sable has the 24 valve durotec 3.0-it was the passage on the face of the a.i.manifold that caused all of my egr problems. Who told you that, a dealer, mechanic? did they check everything first? did they apply vacum to the valve and see if it was faulty? did they replace the dpfe?

60% of late 90's early 00's Ford and Mercury p0401's are a bad dpfe sensor. 30%are a clogged egr passage after the throttle body in the manifold. 9% are either the valve or the evr vacum. that leaves 1% to be either a leaky hose, or a pcm. check again before you drop bookoo bucks on a pcm

good luck

mb

It has to do with DPFE sensor circuit high voltage detected. EGR temp sensor malfunction. That is all I can find. Hope this helps.

I found this: P1401 Differential Pressure Feedback EGR Circuit High Input

It is fairly common for this to be a problem with the sensor, not the EGR valve. The message is misleading. Also, it there is a 1400 message with it, it is most certainly the sensor, not the valve.

jcjimz

The advice above about the passage from the EGR to the throttle body is good. Usually you don't have to replace thr EGR but if you're taking it off replace it any way, it's not expensive. On the 3 liter DOHC Ford, Mercury engines the problem with the EGR is most always the passage through the manifold to the throttle body. Take off the EGR and the throttle body. From the EGR the port makes a hard right to the throttle body that you can not see. On the throttle body side there is a C shaped groove that is on the left of the main large port. It is probably full of carbon. Get a spray can of B-12 Chemtool and clean it out. You will see on the upper side of this groove that there is a small port. This goes to the EGR. Take your B-12 and clean the entire port then spray it into the port to the EGR. Let it sit then spray it again. Take the hose from the B-12 and spray it from the EGR side too. Let it soak. Do this until you get a steady flow of B-12 from the EGR to the throttle body. After weeks of spending money and time replacing things this was the entire problem and have been told by a reputable mechanic that 90% of the time that's the whole problem.