P0401 Keeps Coming Back
#1
P0401 Keeps Coming Back
I have a '97 F150, 4wd with 4.6l engine. My check engine light keeps coming on with code P0401. I've replaced the EGR valve, the DPFE sensor and the EGR vacuum regulator. I've disassembled and cleaned the ports from the EGR to the intake. If I apply vacuum to the EGR valve, the engine stumbles as it opens. The vacuum lines seem to be ok. I have vacuum coming to the EGR vacuum regulator. I can reset the code but soon it will come back on. Does this mean the PCM is defective or is there something else I'm overlooking?
Last edited by f150drvr; 08-29-2016 at 01:22 PM.
#2
Member
2 things come to mind, either the wires from the pcm to the egr solenoid are shorted to ground or open or the pcm is bad. The sensor itself is working and telling the pcm it's not seeing it open/closed when commanded.
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