Problem: Clogged DPF and P0401 Insufficient EGR flow
When I bought my truck, it had a DPF delete done. Our county is requiring emissions testing on Diesels starting this year, so I had to get it ready for emissions testing. I got a new catalytic converter and bought a used DPF.
Taking this exhaust pipe joint apart was kind of a challenge.
I hooked up a tie-down strap, one on each side to pull the exhaust pipe apart while I beat on the thing to separate it. That worked, eventually.
When I bought the used diesel particulate filter, he told me it was plugged. I used a hot pressure washer to try and clean it out. Hint: expect to get dirty from plenty of back-spray. After what seemed like a thorough spray down, it looked ok, but I soon found out it was still clogged when I installed it.
When I started the truck and started driving, the wrench symbol came on and it said it was on reduced power. After it warmed up a bit, it started cleaning the filter, but after about 11 miles of driving, it said "stop safely now". I wasn't sure what that meant, but it stopped responding to the throttle. I checked the mirror and some blue smoke was coming out of the tailpipe from burning off the filter. So I idled into the neighborhood and decided to see what would happen if I shifted to neutral. As soon as I put it in neutral, it shut the engine off.
I couldn't re-start it. I cleared the codes. It still wouldn't re-start. I asked a friendly neighbor who owned a Chevy pickup to tow me home. He was more than happy to tow my Ford home with his Chevy. He couldn't resist dropping a Chevy/Ford joke.
After a short internet search, I learned that you have to leave the truck alone for at least a half hour with no key cycles. It shut off because the exhaust was overheating. It would be nice if they gave me more information on the dash, instead of just "stop safely now". And if they wouldn't dump so much raw fuel in the exhaust, maybe the catalytic converter wouldn't get so hot.
So, about 45 minutes later, I started up the truck. It fired up like normal. So I did what any redneck pickup truck driver would do. I drove it. It seemed much better, so I drove it down to the local auto parts store to dump my overflowing oil catch pan, and then get the emissions tested on the way home. It still had only about half the power it did without the DPF. But it started getting better later.
When I turned left, some oil spilled out of my oil container and was leaking out the truck bed. I was wondering why some people were so eager to pass me. The check engine light hadn't turned on by the time I made it to the emissions testing place, so I figured it was good to go for emissions testing. I was wrong. It had a pending code for P0401 and the ECU still hadn't completed the catalyst monitor, or the EGR monitor cycle. So I went home and by the time I got home, the check engine light came on for P0401, insufficient EGR flow.
I tried removing the EGR valve, but of course it wouldn't come off. See this excellent video from DieselTechRon for how to take one of these off. So instead, I took out the whole assembly. Here's what it looked like:
Here's a close-up of the EGR inlet. It was packed full of carbon. Cleaning it out was almost like chipping away at a charcoal briquette.
Here's what it looked like after I cleaned it out. I didn't want to spend all day making it look pretty. It just had to be functional.
I pressed down on the top of the valve to see if it moved freely. The motor and spring combined have a good amount of resistance to make it spring back closed. I guesstimate it took about 10 pounds of force to push the valve open manually.
It took a couple of days of driving, but it finally completed the EGR monitor. I had to look up the drive cycle. Clearing the codes (step 1) isn't necessary unless you've completed repairs and need to clear the error codes.
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