P0406 Code Chasing

[cmcolfax]

The basics: 2011 SOHC 4.0 5MT 139,000 miles Unknown maintenance history.

Truck threw a P1406 a few months ago.

Replaced the DPFE sensor.

CEL went away for a few drive cycles.

Came back and threw a P0406.

Replaced the EGR valve solenoid.

CEL went away for a few drive cycles.

Came back and threw P0406 again.

Replaced the EGR valve.

Rinse and repeat.

Still throwing a P0406.

Cleared with my regular code reader and with ForScan.

Thoughts? Ideas?


FWIW... All of this started after I had the oil changed at a freakin' DEALERSHIP!

Yes, I can do my own oil changes.

I used a dealer when I had my F250 (6.2L gasser) because their "Works" service special was $99 and that was more than worth it.

Oil change, tire rotation, video inspection, etc.

Hell my time and effort to rotate four 8-lug 35x12.50x18's is worth more than $99!

When I bought the Ranger I took it to them, same service was $79. Still worth it IMHO.

I moved and got a flyer in the mail from a dealership less than 10 minutes from my new place with an offer of $69, so I took it to them...

 

[franklin2]

With the engine warmed up and idling, can you take the vacuum hose to the EGR valve and stick it onto a manifold vacuum source? When you do this the engine should stall. This will confirm the EGR is working, and the exhaust pipe to the EGR is not clogged.

If it passes this test, the next thing I would do is check the vacuum supply to the valve. With the engine idling, pull the supply hose off, it should suck on your finger.

P.S. I just had a thought. I have never used Forscan, but do you have Bi=directional control with it? Can you turn the EGR valve on manually through Forscan? If you could, same result, the engine should stall. That would test the EGR valve, the solenoid valve, the output of the computer, the exhaust supply pipe, the vacuum supply, all at one go.