CEL code 401, 95 Marquis, runs fine

GARYDALE

MEMBER
1940 FORD

Cel code 401, 95 Marquis, 99k, 4.6. Check engine light (code 401) has been on for a year. Maybe once every 2 months cel light will go off for a couple days and then come back on. Car runs smooth at all speeds including idle. MPG has dropped from 27 to 23.

Put hose on EGR valve, sucked on it while engine idleing and warm, heard it click each time I tried sucking, engine continued to run fine (red flag?). Pulled off green hose on EGR valve, (which comes from EGR vacuum solenoid, put finger over it and felt a very slight pulsating vacuum.

Question 1. Could that solenoid valve be the problem or was it my EGR 'suck test' showing that the EGR valve is bad. If that is actually a proper EGR test, since engine runs smooth at all speeds? I think I am getting something backwards.

Question 2. Are the EGR vacuum solenoid, EGR position sensor, and DPSE sensor 3 different items? After readin many posts, I'm a little confused as to even locate them on my car. Thanks for any feedback.

5 Replies

TAURUSWHEEL

MECHANIC
718 POSTS

Those three items are different in their operation, vacuum solenoid is controlled by the pcm, it regulates amount of vacuum applied to the egr valve according to engine conditions, egr position sensor sits on top of the egr valve and sends a signal to the pcm indicating egr valve position, dpfe sensor reads flow and makes adjustments accordingly, dpfe sensors on Fords are notorious for failure

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Saturday, March 10th, 2007 AT 10:36 PM

GARYDALE

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4 POSTS

I previously printed out some pics of my engine with lots of sensors, solenoids, and module locations. None show Egr position sensor. Top of my egr valve only has a hose connection coming out of it. None of my pics show location of a DPFE sensor.

I guess by now I wouldnt know how to check if I did find it. I'll find some more pictures.

Until I locate dpfe, does my question # 1 have any validity as to whether my egr valve or solenoid with a pulsating vacuum might be a concern? I thought when I sucked on it during idle, the engine was supposed to run rough, showing egr was at least opening up and working to cause rough idle etc? Thanks

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Saturday, March 10th, 2007 AT 11:37 PM

TAURUSWHEEL

MECHANIC
718 POSTS

The dpfe sensor is usually gray in color, follow the metal tube from the egr valve, there will be a nipple with a rubber hose that should lead to the dpfe sensor, some of the sensors use 2 hoses, some use one(pfe) I'm not sure of your car specs. Egr position sensor is mounted on top of the egr valve, has a loaded plunger that moves up and down with egr operation. Your post indicates you don't have one, only a rubber hose from the egr valve. The egr vacuum regulator may make a little noise, there is vacuum attached to it, the pcm regulates the amount delivered to the egr valve to control the amount of flow. Sometimes if there is an issue with the operation of the vacuum regulator, it may set a code in the hard memory, but not turn on the cel. What is code 401? I don't see it listed in my book? If you apply a vacuum source to the egr, does the car run rough? Doesn't take much vacuum, couple of inches will open it up, or less. Do you have a vacuum pump?

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Sunday, March 11th, 2007 AT 3:55 PM

GARYDALE

MEMBER
4 POSTS

I'll see if I can get a vacuum guage. I guess sucking on it isnt enough while running, even though I can hear the plunger move up and down while sucking when engine is off. Car still runs fine at all rpm. Code 401 at auto zone was' insufficient flow' in egr system. Their book lists 401 402 403 etc.

I located the egr position sensor. Aparrently that is what they call the plunger on the top half of egr valve. Back in my days ( Andy Roony- 60 minutes), they just called it a plunger, I guess thats why I coulnt seem to find it. Now it seems to be called a sensor.I'm learning anyway. And the vacuum control solenoid is a piece plastic. In my day everthing called solenoid was made of metal. Learned something again.

Found the dpse sensor. Looks like a 2' x 3' piece of alumimuim with 2 hoses going into the bottom of it.I think I'm catching on. Both of these hoses from dpfe go directly down and hook on to 2 tubes comeing from below the egr valve. Both the hoses and tubes down there look in great shape. On my 92 marquis it had a long metal tube with a rubber elbow in it etc.

Too bad that I dont have a neighbor mechanic living out here in the sticks, I could have learned all this stuff in about 10 seconds. At least I can still type pretty good. Thanks for you patience

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Sunday, March 11th, 2007 AT 8:47 PM

GARYDALE

MEMBER
4 POSTS

Finally put vacuum guage on EGR valve. It wont hold any vacuum, only clicks when vacuum applied. I think I have found the problem. Did I? Strange how car still runs perfect except for 3 less mpg. Thanks for helping