Well had to make a trip yesterday from northern Indiana to Charleston, WV and back. About 3 hours into the trip my check engine light came on. My truck is an 06 f350 that's all stock with just 118k miles on it. Using my torque pro app I checked the code and it came up as po401 for the low flow in egr system. I was already watching my monitor for the engine and nothing seemed to be out of ordinary. Truck was running about 65mph on cruise and ect was around 195-200 and oil temp stayed around the 200-205 mark. Never seemed to have any problems out of it and it stayed running ok the rest of the trip. Temps did seem to start to increase a little if I was sitting idling for a bit.

Haven't started it up for over 20 hours now but the degas bottle is low on coolant. It doesn't look discolored or anything inside and coolant looks clean. Is there anything else I should look at before I take it to shop? This is my first diesel but am mechanically inclined to work on it. Could the code be thrown for low coolant flow thru egr cooler or is it based off exhaust flow?

This is the first problem I have had with the truck since we got it back in October 10k miles ago. Hopefully I didn't hurt it any by driving it back.

 

P0401 is low flow of exhaust gases through the EGR valve to the intake. It’s a diagnosis of the EGR valve for emissions, nothing to do coolant flow through the EGR cooler itself. Coolant level or condition would not be impacted unless the cooler was leaking and damaged the valve.

The routine I would do is park nose down overnight, pull the valve and look for coolant wetness, you may not have any, but it will ease your mind. The next thing is to try to clean the EGR valve, which isn’t a 100% success rate, or replace it with a Motorcraft new valve.

Take a picture of the valve and intake interior, those who have dealt with this can assess the situation.

 

I have an 05' and at 118K had the same thing; but a new EGR valve, new EGR cooler (no leak, just couldn't figure how to get it clean) and cleaned everything else, and it was fine. YMMV good luck Russ

 

I am gonna pull the egr valve tomorrow to see how it looks. Should I be planning on an egr cooler as well or just start with valve and go from there?

 

Unless you've identified a coolant loss condition through the cooler and/or severe carbon buildup in the cooler, NO. I suspect that removing the EGR valve will reveal the answer as to why P0401 is setting. It may be a wise idea to have a new Ford/Motorcraft EGR valve on hand due to the likelihood of damage to the valve during removal. Removing and cleaning out your IAT #2 sensor of carbon buildup would be a good idea too, since that sensor provides one of the inputs to the PCM to calculate EGR flow.

 

2nd on the no for the cooler unless it's failed.

 

So is it safe to drive the truck back and forth to work a couple days till parts get in or should I let it sit? Just don't want to do any damage.