P2302

P2302 means the PCM detected a fault on the SECONDARY circuit of ignition coil A — the high-voltage side that fires the spark plug, typically diagnosed by the PCM watching the burn time (spark-line duration on a scope, usually 0.8-2.0 ms for a healthy coil firing a fresh plug) or by detecting that the expected 15-40 kV secondary firing voltage demand exceeded the coil's capacity. Open-secondary is the most common P2302 subcondition — the coil's secondary winding has failed open, or the boot/spring contact down to the plug terminal has carbon-tracked, corroded, or burned through. Cheapest-first ladder: (1) Pull coil A and inspect the spark-plug boot for carbon tracks (black wandering lines on the inside of the boot insulation), oil contamination, or arc-through holes — a $15 boot + dielectric grease often resolves what looks like a $180 coil failure. (2) Pull the plug and read it — a normal-but-dead plug with no burn marks confirms no spark reached it; a sooty plug with normal gap confirms the secondary side fired but the plug was fouled. (3) Ohm the coil's secondary winding (most multimeters with a high-ohms range will read it through the boot or plug-tower) — spec is typically 5K-25K ohms depending on platform; an open reading (OL) confirms a failed secondary winding. (4) On a scope with a secondary pickup (kV probe), watch the firing line and burn line during a snap-throttle — a firing line above 25 kV with a short burn line indicates a worn plug or wide gap stressing the coil; a flat or missing burn line indicates open secondary. Expensive-misdiagnosis caveat: swap coil A to an adjacent cylinder before replacing — if P2302 follows the coil, it's the coil; if it stays, the spark plug, plug well, or harness is the problem. A $40 coil swap-test saves $80.

Vehicle-specific patterns: 2004-2010 Ford 4.6L/5.4L 3V Triton (F-150, Crown Vic, Expedition) is the king of P2302 — the long extension boot down into the deep plug well traps moisture, oil mist from leaking valve-cover gaskets, and carbon residue, all of which carbon-track the boot and short the secondary to the cylinder head; replacing the boot + spring contact + dielectric grease fixes 70% of P2302 cases on this engine without touching the coil. 2005-2014 GM LSx V8 (LS1/LS2/LS3) mounts COPs on the valve covers where heat soak degrades the boot rubber — boots get hard and crack around 80-100K miles. 2011+ Ford 5.0 Coyote uses a shorter boot than the Triton but still sees boot-tracking around 90K. 2007-2018 Toyota 2GR-FE / 2AZ-FE secondary failures are typically full-coil failures rather than boot-only issues — Toyota's coil tower design is more sealed against moisture than the Ford Triton. Mazda RX-8 Renesis rotary uses paired trailing and leading coils (not strictly P2302 territory but the secondary-circuit symptom is identical) — the leading coils fail first around 50-70K miles from the rotary's high firing frequency. Common pattern: coil A usually = cylinder 1 but verify against the OEM wiring diagram. Estimated repair: $15 (boot + dielectric grease) to $400 (full coil set on a V8).