P0280

P0280 indicates a high-voltage (open) condition on the cylinder 7 injector control circuit, meaning the PCM commands the driver low but cannot pull the line down. Cheapest test first: swap injector 7 with another cylinder and clear codes; a migrating code confirms a broken injector winding. Measure resistance with the connector unplugged: 11 to 17 ohms expected on PFI, 1.5 to 4 ohms on GDI; open circuit (OL) confirms a broken winding. Key-on engine-off, the feed pin should show battery voltage and the driver pin should rise to near battery voltage through the injector coil; if the driver pin reads 0V with injector unplugged and key on, the harness or PCM driver is open. Scope confirms a clean square pulldown during cranking with pulse widths of 4 to 8 ms on cold-crank PFI engines and 0.5 to 1.2 ms on GDI. Caveat: on returnless fuel systems a single failed injector can pull rail pressure low enough to trigger neighboring lean codes (P0171/P0174), so don't chase trims until P0280 is resolved.

Vehicle-specific patterns: 2004 to 2008 Ford F-150 5.4L 3V triton again sees P0280 from the same passenger-bank harness chafe pattern as P0274; 2007 to 2009 Toyota Tundra 5.7L 3UR-FE has reported broken injector connector locking tabs that lift the terminal off the pin; 2005 to 2010 Chrysler 300C 5.7L Hemi has the Mopar TSB 18-040-07 cracked-winding pattern on the rear-bank cylinders. Estimated repair: $40 to $530.