Check Engine - P0401

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14.6@97MPH

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I've got a check engine light with the code P0401 on my 1998. This is the only code showing. It translates at AutoZone to an EGR problem. I don't notice any driveability problems.

Is this most likely a bad EGR valve? I've been searching some other posts on this problem and I'm not sure.

Is replacing this really that hard? Also, I've been searching on replacing it, and it doesn't look easy.

So far in searching all the Mark VIII message boards, a bad EGR doesn't seem very common?

If it matters, my 98 has 104k miles. I also never replaced an EGR on my 1993 quarter million mile Mark VIII.

Thanks,
Ken
 
More than likely the DPFE is bad, or it had a momentary loss of proper flow thru the sense tubes. Did you clear the code or just read it? I would simply clear it and see if it comes back after a weeks time. EGR valves are hardly ever bad.
 
Psychostang said:
More than likely the DPFE is bad, or it had a momentary loss of proper flow thru the sense tubes. Did you clear the code or just read it? I would simply clear it and see if it comes back after a weeks time. EGR valves are hardly ever bad.
Click to expand...

What is a DPFE and where is it? Sorry for the stupid question.

I did unplug my battery for long enough to turn the check engine light off, and it came back on again after another 150-miles or so. Is unplugging the battery enough to clear the codes?

Ken
 
On OBD-II vehicles, disconnecting the battery does absolutely nothing. It only clears the KAM, which now requires the vehicle to re-learn all parameters. It may take a little while before all drive cycles are completed. Go back to autozone, and have them clear the code, not just read it.
 
If you buy a OBDII reader for I think it is 24 bucks, you can read them yourself and clear them also yourself. Just a useful tool to have at home when you need it.
 
+2 DPFE ford has had a tsb out for a few years now stating if you get a egr code on any FoMoCo veh replace the dpfe first. and 9.9 times out of 10 thats it
 
Update - I did get a cheap code reader, reset the code twice and the same code came back on twice.

I just ordered the DPFE sensor from Max along with the vacuum tubes that go into it. My local dealer wanted way too much $$ for the part.

Hopefully this fixes my problem.

Any advice on how to replace this part? It looks like I have to take the wipers off then the windshield wiper cowel off and I should have enough access to get to the DPFE sensor?

Ken
 
This pic may help you visualize things a bit better. The DPFE sensor is mounted to the same bracket that holds the IMRC controller behind the intake. You should only have to remove the passenger side cowl to get to it, and maybe not even that.

There aren't any "vacuum" lines connected to it, there are 2 hi-temp hoses that connect to the EGR tube below the DPFE sensor to monitor the flow.

HPIM2357rr.jpg
 
i had this code on the wife's Taurus and as i was taking it apart to replace the dpfe i found the line blocked with crap(carbon). cleaned it out and turned out i didnt need any parts, ,but as chicken and others have said, its almost always the dpfe itself
 
Had the DPFE go out on my Town Car, common problem on Ford's. I know for a gen 1 the cowls get in the way but not sure on a 98.
 
Doug thanks for the pics! I found some pics on .org too. Similar pics to yours where a can see a small part of the sensor. I mostly know where it is by feel vs. sight. I'll try and post some better pics of the sensor after I get the cowl out.

I also know the new sensor will have a slightly different design and color.

And yes, the tubes Max is sending me are 'high temp' tubes. He actually had a part number for each of the 2-tubes that go into the DPFE sensor, he had them in stock and is sending them to me with the sensor. I can't see those tubes at all, but I can feel them. Might as well replace them in case that is part of or all of the problem.

Ken
 
I've replace the DPFE sensor and reset the CE light (just replacing the sensor did not turn the CE light off). I did take the cowl out to get to it, and getting that out wasn't easy or fun.

Next dumb question. How long or how many miles do I have to run the car before it goes through all it's drive cycles (to make sure the CE light doesn't come back on)?

I still haven't put the cowl back on, and don't want to until I know I've fixed the problem 100%.

So far I've driven 30-miles and had the car running for a total of about an hour.

Doug - I pm'd you about this too.

Thanks,
Ken
 
Check engine light is back on :( 1 1/2 hours and 50-miles is not enough driving for the car to go through all it's test cycles. The CE light came back on after ~60-miles. Of course I put the cowl back in by now.

I guess I'm the .5% of the cars that replacing the DPFE sensor does not fix error code p401. :confused:

Between this and the ABS problem, this car is not making me happy.

Doug - I may be down next week, or when you have time, to check my CE and ABS problems.

Ken
 
No reason to worry much about the cowl, as it doesn't seem that the DPFE sensor is the issue. I'd suspect the EGR valve or the vacuum control solenoid now.
 
did you hook up the hi temp hoses backwards? im not sure what one goes to what side off the top of my head, but i know not to switch them......
 
chicken said:
did you hook up the hi temp hoses backwards? im not sure what one goes to what side off the top of my head, but i know not to switch them......
Click to expand...

You can't really hook the hi-temp hoses up backwards because they are different sizes. At least on a 98 Mark they are different sizes.
 
Update! I did the suck test on my EGR valve and it works fine. I put a vacuum hose on the EGR vavle and sucked on it while the car was running and it almost stalled.........EGR valve works.

I next replaced the EGR vacuum solenoid (finally an easy repair, easier than wiper blades!). Cheap part too, only ~$30.

I pulled the codes right after I changed the vacuum solenoid and got P0443 (P0401 went away)? I did not let the car run for very long, or drive it any distance yet. I reset the codes and I'll see what happens when I put some miles on the car.

Doug - Thanks for posting these next possible fixes!!

Ken
 
14.6@97MPH said:
Update! I did the suck test on my EGR valve and it works fine. I put a vacuum hose on the EGR vavle and sucked on it while the car was running and it almost stalled.........EGR valve works.

I next replaced the EGR vacuum solenoid (finally an easy repair, easier than wiper blades!). Cheap part too, only ~$30.

I pulled the codes right after I changed the vacuum solenoid and got P0443 (P0401 went away)? I did not let the car run for very long, or drive it any distance yet. I reset the codes and I'll see what happens when I put some miles on the car.

Doug - Thanks for posting these next possible fixes!!

Ken
Click to expand...

You're welcome.

If you still have issues, look for vacuum leaks in the lines hooked up to the solenoid and the EGR valve.
 
P0443 now on 98 LSC

P0443 is the new code :( I’ve reset the CE light a couple of times and put some miles on the car between resets. I only get 1-code now and it is P0443. P0401 is gone, so the fixes above (DPFE sensor and EGR vacuum solenoid) have gotten rid of that code.

As Doug suggested, I have checked my vacuum lines around the EGR and the EGR vacuum solenoid and replaced 1-small one that was probably OK anyway. The rest of the lines looked good.

Any suggestions? P0443 doesn’t seem like a common Mark VIII problem? I’ve searched this site and the other Mark VIII boards and there are not a lot of posts (if any) on this code.

Help!!
 
EVAP - From the Service Manual:

The diagnostic trouble code (DTC) associated with an electrical fault of the EVAP canister purge valve is P0443 (EVAP system control valve circuit malfunction).
 
Last edited:
Sorry for the dumb question. Any pics of what the EVAP solenoid looks like and/or exactly where it is? I'm looking in the rear passenger side engine compartment (from the top) and I'm not seeing it :( The solenoid should have at least 2-vacuum lines and one electrical connection based on what they look like for other cars? I'm not finding any pics of what ours looks like online. :(

Ken
 
14.6@97MPH said:
Sorry for the dumb question. Any pics of what the EVAP solenoid looks like and/or exactly where it is? I'm looking in the rear passenger side engine compartment (from the top) and I'm not seeing it :( The solenoid should have at least 2-vacuum lines and one electrical connection based on what they look like for other cars? I'm not finding any pics of what ours looks like online. :(

Ken
Click to expand...

Turns out that it's in the passenger fenderwell, so I was probably wrong about you disturbing it. :(

The connector is at the top of this pic with the red and lg/bk wires.

HPIM1497.jpg
 
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