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Well, I thought I had this thing fixed...apparently not. I have the P0401 code, I have replaced the EGR valve, EGR vac solenoid, DPFE, EGR tube/hoses from the tube to the DPFE. I am still getting the P0401 code, as well as high negative fuel trims (photo attached). Anyone have any ideas? Thanks in advance.
I sure have seen some bad Duralast sensors right out of the box
Last one I had, I had to re do the pinpoint tests (pissed me off) and I installed a junkyard one to fix the truck, then ordered a expensive Ford one
Getting a bad sensor would be the kind of luck I have, honestly. Lol. I haven't had any problems with Standard Motor Products parts, but this one came from Amazon, and I have heard they sell the parts that were rejected from the factory. Not sure if that's true or not, but I figured I would give it a shot.
Well, I switched out the DPFE with a brand new one from Oreillys, all it did was take the code out of "pending". Could the MAF be bad? It's reading around 7+ at idle...that's a little high isn't it? I'm grasping at straws now lol. LT fuel trims are barely better than before, they went from -14 to - 9
EGR ports are probably clogged. Apply vaccum to the valve with the engine idling and it should stumble badly or stall if the ports are clear. Need fuel trims for both banks to figure that one out. Long and short, both banks, idle and 2500 rpm
EGR ports are probably clogged. Apply vaccum to the valve with the engine idling and it should stumble badly or stall if the ports are clear. Need fuel trims for both banks to figure that one out. Long and short, both banks, idle and 2500 rpm
I have already cleaned the ports out, i took the entire throttle body assembly off and cleaned the heck out of everything. I double checked every port when I did so. The fuel trims are roughly the same on both banks.
7 volts is high for the MAF
With that kind of high MAF number, the processor thinks you are barreling down the road and will open the EGR valve
I was wondering about that, ive cleaned it with MAF cleaner a few times with no change to the number. I have had codes in the past for O2 sensors, so all 4 of those are new as well and operating as they should...switching voltage. The cats are also brand new as of a few weeks ago. The intake manifold is new, EGR valve, EGR vac solenoid, EGR tube, and DPFE are new...and I have replaced the EVAP solenoid (had a code for it), the vaccum lines are new, and PCV valve is new. About the only thing I haven't changed is the MAF sensor.
Not sure about that MAF reading. Did you open the egr valve while idling to see if the engine responds? What is the DPFE voltage with key on engine off? Does it change with the valve opened while engine is running? Are you sure the hoses are installed on the correct ports? Whats the fuel trims on both banks at idle and 2500 rpm?
The P0401 code is gone, it's not even pending anymore...all I have now is negative fuel trims at idle. They get better when throttle is applied, always a new problem. 🤬
