If the fuel filter has not been disabled, air in the fuel line could be causing these OBD2 codes. This is a common issue in 2001 V6 Mustangs with the 4.6L engine. Air intrusion in the fuel system can lead to misfires (P0304, P0305, P0306) and increased exhaust emissions (P0402). Ensuring proper fuel line priming and checking for leaks or blockages is essential for resolving these faults.
That might have been the root cause of the new error codes appearing.
I meant fuel pump , if you disabled the fuel pump that is what caused the code . nothing to worry about.
I work at a Ford dealership and have replaced many DPFE sensors. Simply pull the sensor off—some are stubborn. Make sure to note the hose sizes (two different diameters) before removal, as they can be tricky to reconnect properly.
Thanks, cash! That info on removing the DPFE sensor is very helpful. I was pretty sure it was the issue but didn’t want to yank it off and damage anything else. My car already has enough problems—I’m getting a new sensor tomorrow. If that doesn’t fix things, maybe driving it off a cliff or into a concrete wall at 100 mph (if I can get past 60) will solve everything! lol
For a 1999 CSVT, is the DPFE sensor located near the EGR valve?
Thanks to everyone who helped! Your tips were incredibly useful. The problem is now resolved—I replaced the DPFE sensor and the 'Service Engine Soon' light has disappeared. It's funny how just one small sensor could cause such widespread issues. Hope this answers your question, ol_redsy. I found this info in my Haynes manual—likely applies to your engine too.
What do you mean by 'disable the fuel filter'? How exactly do you do that? I unplugged the fuel shut-off switch in the trunk and ran the car until it shut off—was that what you meant?