P2307 — Ignition coil C circuit voltage too high

The engine control module detected an unusually high voltage in the ignition coil C primary circuit. This usually means there is an electrical problem like a short or wiring issue affecting the coil that fires one of the cylinders. It can cause misfires, rough running, or poor performance if not addressed.

Common causes

The cause is almost always one of a few things. Here they are — P2307 rarely comes from anything outside this list:

• Faulty ignition coil C
• Damaged or corroded wiring/connectors
• Short circuit in coil wiring
• Faulty ignition control module
• Poor electrical ground connection

Where to start

In the order a sensible mechanic would work — the cheap checks first, the expensive replacements only after:

1. Inspect and repair wiring and connectors
2. Check and clean electrical grounds
3. Test ignition coil C and replace if faulty
4. Check ignition control module function
5. Replace ignition control module if necessary

That is what holds for P2307 in general. From here it depends on your engine — tell me which car it is and what it does, and I will give you the steps for it: real procedures, torque figures and diagrams instead of general advice.