1998 Ford F-150 P1408 Code: Backfiring and Stalling with Romeo Engine (VIN W)
I own a 1998 Ford F-150 with 4WD and a 4.6L 'Romeo' V8 engine (VIN digit W). The vehicle has been throwing up a P1408 diagnostic trouble code. While the truck exhibits noticeable backfiring and severe hesitation during acceleration—whether cold or warm—the symptoms don't seem to fully align with the P1408 code. We've already replaced spark plugs (NGK), fuel filter, fuel pressure regulator, and EGR vacuum solenoid, but the issue persists and the P1408 code remains active. Compression tests on all cylinders show normal readings. Can anyone confirm if this code is typically linked to these symptoms or suggest further diagnostic steps? Any insights would be greatly appreciated.
P1408 relates to the Diesel Particulate Filter Efficiency (DPFE) sensor. However, in a 1998 Ford F-150 with a 4.6L V8 engine, this code is more commonly associated with the intake air temperature or fuel system issues rather than direct diesel particulate concerns. It may indicate a faulty DPFE sensor or a vacuum leak in the intake system. Check for intake leaks and ensure proper sensor connections. Also verify that the EGR system is functioning correctly, as it can trigger this code under certain conditions.