Hey everyone,
Have a 98 Ranger, 3.0 with 84 K miles on it.

The check engine light came on, reading P0401, AutoZone said to replace the EGR sensor, so i did.

The light came back on with the same code, so i was reccomended to clean out the throttle body with cleaner due to carbon build up.

I've done that three times! and the code stays off for about 50 to 100 miles then the same code comes back up

Any ideas what to do next.

Thanks

 

If it has the sensor that has 2 hoses going to it pull them off and bend them to see if any crud comes out. If so replace them with new hoses. It is not uncommon to have this problem. Good luck.

 

The two sensors that attached to the intake that are right before the throttle body?

 

as WP said.........check/replace those 2 hoses that run to the DPFE sensor........99% of the time on a Ford when you get the p0401 code it is a bad DPFE sensor(the heat kills them)........since you have a new EGR valve I would check the 2 rubber hoses and also makes sure the egr tube is not rusted out....if they are fine replace the DPFE sensor...rockauto has a motorcraft for $60 or maybe you can get one from a store with a GOOD warranty........

*rockauto list it is emissions and calls it a EGR Pressure Feedback Sensor

 

With only 84K miles its unusual to have a P0401= insufficient EGR flow, problem.

That said. I agree the DPFE sensor belonged on your suspect list, as does its interconnecting vacuum lines to the manafolds, especially if the engine is using oil, which it shouldn't be with only 84K on it.

There are four other things that belong on your suspect list that can cause an insufficient EGR flow problem. The EVR/Vacuum Switching Valve that the computer uses to control the EGR valve, the vacuum lines from the EVR to the EGR valve & the EVR & EGR valves diaphragm & the feedback orifice below the ERG valve. If any of the EGR system vacuum control, or feedback components are leaking vacuum or restricted, it'll upset its operation.

SO, you need to do some more inspection of the vacuum lines, looking for signs of dryrot cracks, hard or soft rubber/poorly fitting vacuum hose connections to their barb connections, rub, cut, kink signs on vacuum lines & using a hand vacuum pump like a mighty vac, ect, check that the EVR & EGR valves diaphragms are holding vacuum & that the EGR valves shaft moves when vacuum is applied & that the orifice below the EGR valve is clear of carbon, that feedback orifice below the EGR valve needs to be clear of carbon, as its also a common problem point, especially if the engine is using oil. You'll have to remove the EGR valve to view, or access it for cleaning.

More thoughts for consideration, let us know how your EGR system trouble shoot goes.

 

Well i talked to the guy i bought the truck from, I've only had this truck for a couple months.
He told me he had replaced the EGR Valve and the EGR Vacuum Solenoid. (still not fixing the code)
With those being brand new... I guess the lines and the EGR Pressure Sensor are left to check then.


And i've cleaned all the carbon out of the throttle body and EGR Valve with a throttle body cleaner.
I could take off the orfice below the Valve and clean it of any carbon build up.