P2301

P2301 means the PCM detected a high-voltage condition on the primary control circuit of ignition coil A — the IGT command line is reading higher than the expected 0-5V (or 0-12V) reference, or the coil is failing to pull the line low when the PCM commands a charge event, or the PCM's current-sense feedback never sees the expected 5-15A primary current ramp during the 2-6 ms dwell window. Cheapest-first ladder: (1) Visually inspect the coil A connector for backed-out pins, green corrosion, or a chafed wire shorted to 12V — a wire pinched against a bracket and rubbed through to a 12V source is a classic P2301 cause. (2) Ohm the primary winding pin-to-pin — spec is 0.4-1.5 ohms; an open primary (OL reading) is a common cause of the PCM seeing the IGT line stuck high because there's no winding to pull current through. (3) Scope the IGT trigger pulse at the coil during cranking — you should see a clean 0-5V (or 0-12V) square wave with 2-6 ms dwell; if you see the trigger pulse but the line never collapses to ground, the coil's internal driver transistor is failed open. (4) On platforms where the PCM uses an external ignition module instead of internal coil drivers, ohm the module's ground reference and check for the expected current-feedback signal. Expensive-misdiagnosis caveat: swap coil A with the coil from an adjacent cylinder and clear the code — if P2301 follows the coil to the new cylinder, it's the coil; if it stays on the original cylinder, it's the harness, the connector, or the PCM driver itself. A $40 coil swap-test saves the $80 misdiagnosis fee.

Vehicle-specific patterns: 2001-2007 GM LSx V8 (LS1/LS2/LS6 in Camaro SS, Corvette, GTO, Silverado SS) sees P2301 most often from the OEM coil-pack pigtails where the insulation hardens and cracks against the valve-cover mounting bracket — repair the pigtail rather than replacing the harness. 2004-2010 Ford 4.6L/5.4L 3V Triton COP coils throw P2301 when the long extension boot allows secondary spark to track back up to the primary terminals and damage the internal driver — replace the boot at every plug service to prevent it. 2011+ Ford 5.0 Coyote uses a coil-pack design that's more reliable than the Triton COPs but throws P2301 from melted connectors when underhood temps run high. 2007-2018 Toyota 2GR-FE / 2AZ-FE rarely throws P2301 before 100K miles; when it does, the failure is typically the coil itself rather than the harness. Mercedes-Benz M271 (1.8L supercharged 4-cyl, 2003-2012 C-Class/E-Class) and M273 (5.5L V8, 2007-2014 E-Class/S-Class/CLS) sees coil primary failures clustering at 80-120K miles — the M273 in particular has had multiple TSBs around coil-pack heat shielding. Common pattern: ignition coil A usually = cylinder 1 on most Ford/GM/Toyota platforms but can vary — verify against the OEM wiring diagram before swap-testing. Estimated repair: $40 (single coil DIY) to $400 (full set + labor on a V8).