After installing the Sinister Diesel EGR Cooler, a new stock turbo, new EGR valve, and new #7 and #8 injectors, I am still getting the P0401 code. Each of those items needed to be replaced, by the way.

The motor runs fine; it just continues to throw the code. It has been to the dealer, and they can't figure it out. Is there a diagnostic procedure I can follow to hunt this elusive problem down?

 

did you check the connector?

 

I did. The connector is okay. No cracks, wiring solid. Makes positive connection.

 

Visual inspection reveal any small white lines, like a lighter color on the wire near the plug, sort of like an over bent wire?

Did you electrically check it?

That code is normally a low flow code, you could have a bad sensor.

 

P0401 - Exhaust Gas Recirculation Flow Insufficient Detected


my bad you have the cooler


Post IAT #1 & 2 at KOEO after cold soak


check the plugs

 

Did you have this code before the work was done? I had this issue, and the new EGR valve I bought wasn't any good. Borrowed one from a friend, FINALLY, to figure it out, but not before I pull or most of my hair.

 

Check your IAT2 sensor. It's located here.



Make sure it's plugged in good and wires are in good shape. If that's ok pull it and clean it, they can get quite dirty which causes a delayed response. If the issue persists either the sensor is bad (not a common problem) or the EGR valve is carbon fouled and blocked or is defective and really isn't opening up. Usually you will get additional codes if the EGR valve has failed electrically.

The air from the EGR system is very hot and when the EGR valve opens and allows these gasses to pass, it causes a corresponding rise in IAT2. That's the PCM's primary monitor for EGR flow.

 

If you have a scanguage, check the EVD and EVM. They should track about the same. I throw the same code intermittently, when I do, at temp, the EGR is getting demand, but not showing a measurement. I believe it is a faulty egr, gonna try a new one in a day or so.

 

Update: I have replaced the IAT2 sensor, and still get the P0401 code. The EGR valve was new, but cleaned anyways at the same time.

Unless anyone has other ideas, I am going to start replacing connectors.

 

This may or may not be of help in your case, gut it is worth a shot.

Good luck.
Ed

 

get a dvm and check circuits
Don't want to miss a possible wire chaff

 

Was the EGR valve a Ford unit or ebay China knock off? I'd try an oem if you have access to one.