2005 Ford F150 OBD II Codes P2198, P300, P305, P306, P308 - Diagnosis and Fixes
I own a basic OBD-II scanner that's showing codes P2198, P300, P305, P306, and P308 on my 2005 Ford F15-0. I've already replaced both upstream oxygen sensors (between the engine and catalytic converter), which provided slight improvement. The truck previously required me to pump the gas pedal to start — now it starts without that effort, but still runs roughly, lacks power, and produces white smoke when idling after warming up. There was no smell of water or antifreeze detected. Since I'm on a tight budget, I don't know where to go next. I read online that changing the engine oil might help — though I don’t understand why, I’m willing to try it. The issue began with backfiring from the intake during startup. I also heard one instance of a strange knocking sound coming from the bottom of the engine, but it hasn't returned since. I'm concerned about potential damage and would hate to replace all spark plugs unnecessarily. Can anyone guide me on what steps to take next? A fuel pressure test under KOEO (Key On, Engine Off) is something I'd like to do, as well as checking spark plug condition — wet, dry, black, or tan — to confirm proper ignition. Any advice would be greatly appreciated.
All of these are P-codes. Is this a 4.6L or 5.4L engine? Has there been any recent modifications to the vehicle? P2198: Oxygen sensor stuck in rich condition, Bank 2 Sensor 1. P300, P305, P306, P308 indicate misfires on Bank 2 — that's the driver's side. With an OBD-II scanner, check fuel trims and B2S1 voltage readings. If you don't have a scanner, remove the spark plugs and visually inspect them for wetness, dryness, black or tan deposits — this can indicate misfiring. Ensure all spark plugs are firing properly. Perform a fuel pressure test under KOEO (Key On, Engine Off) to rule out fuel delivery issues. This is a critical diagnostic step.