401 Trouble Code

[Fiberford]

I recently started getting trouble code 401 on my '98 Explorer. I cleaned the MAF once, reset the computer, and it came back the next day. I cleaned it again with another cleaner, the code went away for three days. I know this code reads "EGR flow insufficient" but also know the EGR doesn't work without medium range readings from the MAF. Is this logic correct or I am going about this wrong. Seems like if the code goes away, the MAF needs a real good cleaning.

 

[Msupertek]

Ford Certified Technician

Here is the run down buddy follow my directions and within minutes you'll have it figured out. I you have a DVOM (digital volt ohms meter), probe the grey and red wire with the negative lead and probe (I am pretty sure it is brown and white) the brown and white wire with the positive, you should have somewhere between .60v to 1.10v. Large range but thats a good sign, then apply 10 inches of vacuum with a hand vacuum pump to the EGR (just disconnect the green vacuum line from the EGR and install your line there on the diaphram housing). Your engine should run very noticeably rough when 10 inches of vacuum is applied. Voltage should raise somewhere near 4v or more, if it does not put a new DPFE sensor on it (sensor which detects Exhaust pressure to see if egr is opened), or if when you apply vacuum nothing happens the and the engine runs perfect put an EGR Valve on it. Disconnect the battery for 3 minutes to erase the computers keep alive memory and reset the mil light (malfunction indicator lamp). Your good to go. By the way it is pretty common for the valves to stick on 5.0L, the first thing I usually do is operate the EGR with my hand vacuum pump and see if its stuck. If the car doesn't run rough just go ahead and replace it, there should be a noticalbe drop in rpm and the vehicle should run rough if the EGR is opened at idle.

 

[Robb]

Run the tests, but 9 outa 10 times, the DPFE is shot.

Robb