Ignition Coil "C" Primary Control Circuit Low
P2306 indicates the primary control circuit for ignition coil C is registering a low voltage condition. The PCM (powertrain control module) detects that the coil driver circuit voltage is below the expected threshold, preventing proper ignition coil operation on that cylinder.
What You Might Notice
- Engine misfire on cylinder with coil C
- Diminished engine performance and power loss
- Reduced fuel efficiency
- Check engine light illuminated
- Rough idle or hesitation during acceleration
Most Common Causes
- 1
Faulty ignition coil C
The ignition coil has failed internally or has a short circuit causing low voltage in the primary control circuit. This is the most common cause requiring coil replacement.
- 2
Wiring harness damage or corrosion
The electrical connectors or wiring between the PCM and coil C are corroded, loose, or damaged, reducing voltage delivery to the coil driver circuit.
- 3
PCM driver circuit failure
The ignition coil driver transistor inside the PCM has failed or is malfunctioning, preventing proper voltage control to the primary coil circuit.
- 4
Loose or corroded coil connector
The connector at ignition coil C is loose, corroded, or improperly seated, creating high resistance in the circuit and causing voltage drop.
How to Diagnose It
- 1
Check Faulty ignition coil C — The ignition coil has failed internally or has a short circuit causing low voltage in the primary control circuit. This is the most common cause requiring coil replacement.
- 2
Check Wiring harness damage or corrosion — The electrical connectors or wiring between the PCM and coil C are corroded, loose, or damaged, reducing voltage delivery to the coil driver circuit.
- 3
Check PCM driver circuit failure — The ignition coil driver transistor inside the PCM has failed or is malfunctioning, preventing proper voltage control to the primary coil circuit.
- 4
Check Loose or corroded coil connector — The connector at ignition coil C is loose, corroded, or improperly seated, creating high resistance in the circuit and causing voltage drop.
How to Fix It
- 1
Replace ignition coil C
Disconnect the negative battery terminal, remove the faulty ignition coil C assembly from the engine, and install a new OEM or quality replacement coil in its place.
- 2
Inspect and repair wiring harness
Check the primary control wiring between the PCM and coil C for corrosion, breaks, or loose connections. Clean corroded terminals with electrical contact cleaner and reseat all connectors firmly.
- 3
Clean coil connector contacts
Disconnect the coil C electrical connector and inspect for corrosion or oxidation. Clean contacts thoroughly with electrical cleaner and dielectric grease, then firmly reconnect.
- 4
Test PCM and replace if necessary
If coil and wiring are confirmed good, the PCM driver circuit has likely failed and the PCM module requires replacement or reprogramming by a qualified technician with proper diagnostic equipment.
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