PO401 5.0 | Ford Explorer Forums - Serious Explorations

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PO401 5.0


Well-Known Member
February 10, 2019
Reaction score
City, State
Jacksonville FL
Year, Model & Trim Level
96 Explorer 5.0 rwd
So I’m getting around to turning off the Christmas lights. Working on the PO401, only code accept for an ABS code, and no symptoms. I changed the EGR (I happened to have one, it’s not that hard.) expecting no change. Unsurprisingly, no change. Yes the code was cleared.
So, how can I test the EVR? I don’t have a vacuum gauge, I read Code PO401
so I guess there is a resistance check? Anyone know the values? Any good tricks to find a vacuum leak? Maybe a way to test the sensor connected to the EGR?

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SoooOOOOoooo, I think I fixed it.

I’m a dumbass and forgot to put the little grey gasket on the back of the EGR valve so it wasn’t sealed... however, after installing it properly, I tried pulling vacuum through the line from the regulator to the valve and found a leak in the elbow, I massaged it with some grease and the light has stayed off. While I had it apart I measured the resistance in the sensor, not knowing the values I just looked for change as I actuated the plunger. I went ahead and took pics because people say it’s hard to remove the valve, my way isn’t.

You need a 13 and 15mm stubby ratcheting wrenches, zipties or string. Tie the heater hoses out of the way, and loosen the throttle cable. There is enough room to get the 13mm on the bottom nut and break it loose, it should thread off by hand after. The top nut has plenty of room. Pull the valve back and down and there is enough room to wiggle it out.








Get yourself one of these. Very handy tool to have in your arsenal... $19.99 at Harbor Freight.

That is the Egr valve on the early '96 and '97 5.0 engine. I remember that bottom nut on the Egr to be a real PITA. You only can get a wench on it to loosen a small turn and the rest is by hand while praying the nut doesn't drop.:)

Praying is the correct word! Getting it back on is fun too!
So now the check engine is off, just need to work on the abs