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DTC codes / P23xx · Ignition system and misfire / P2307

P2307Ignition Coil 'C' Primary Control Circuit High

P2307 means the engine computer detected an abnormally high voltage on the primary control circuit for ignition coil 'C', which usually indicates an open circuit or a short to voltage rather than a coil that has failed internally. The computer commands the coil to fire by pulling that circuit low, so a high reading tells it the coil driver is not seeing the expected current flow.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaIgnition system and misfire

Symptoms you may notice

  • Illumination of the check engine light, often with no other symptoms besides the warning light
  • A noticeable engine misfire or rough running, especially under load or acceleration
  • Reduced engine power or a limp-home mode on some vehicles
  • Shaking or vibration felt through the steering wheel and seat at idle
  • A flashing check engine light if the misfire is severe enough to damage the catalytic converter
  • Slightly worse fuel economy over time as the computer compensates for the misfire

Common causes, most likely first

  1. An open circuit in the primary control wire between the engine computer and coil 'C', often from a broken wire or corroded terminal
  2. A short to voltage on the coil 'C' control circuit, which can be caused by chafed wiring rubbing against a metal bracket
  3. A failed ignition coil 'C' with an open primary winding, which prevents current from flowing when the driver commands it
  4. A poor connection at the coil connector or the engine computer connector, including pushed-back pins or water intrusion
  5. A faulty engine computer driver for that coil circuit, though this is less common than wiring or coil faults
  6. A damaged ignition coil harness pigtail from heat exposure or rodent damage

How to diagnose and fix it

  1. Inspect the ignition coil 'C' connector and harness for corrosion, loose pins, or obvious damage, and repair as needed
  2. Swap coil 'C' with a known-good coil from another cylinder and clear the code to see if the fault follows the coil or stays with the circuit
  3. Use a digital multimeter to measure resistance across the primary winding of coil 'C' and compare it to the manufacturer's specification
  4. Check for battery voltage on the coil control circuit with the key on and the engine off, then check for a short to voltage with the computer disconnected
  5. Perform a wiggle test on the harness while watching live misfire data or the code status to catch an intermittent open circuit
  6. Back-probe the control wire at the engine computer and command the coil on with a scan tool to verify the driver is functioning
  7. Replace the faulty coil, repair the wiring, or replace the engine computer only after all other tests confirm the fault

Why coil C circuits fool good technicians

  • A high voltage reading on the control circuit often means the coil primary winding is open, but a loose ground strap on the engine can produce the same code by preventing current flow.
  • Technicians sometimes replace the coil only to find the code returns because the real fault is a chafed wire inside the loom that only shorts when the engine moves under torque.
  • P2307 can be set by a failing engine computer driver, but that is rare; always rule out the coil and wiring before condemning the computer.
  • A weak battery or poor charging system voltage can cause the computer to misread coil circuit voltage, so check the charging system before chasing the coil circuit.
  • On some vehicles, the coil 'C' control circuit shares a ground path with other coils, so a fault in a neighbouring coil circuit can trigger P2307 as a companion code.

Can I keep driving with P2307?

You can usually drive the vehicle to a repair shop if the check engine light is steady and the engine runs smoothly, but avoid hard acceleration and heavy loads. If the light is flashing or the engine is misfiring badly, stop driving because unburned fuel can overheat and destroy the catalytic converter.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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