P2305
Ignition Coil B Secondary Circuit
Ignition / misfire
Generic OBD-II
Medium
What it means
P2305 means the ECM detected a fault in the secondary (high-voltage) circuit of ignition coil 'B'. That cylinder may not spark properly, causing a misfire, rough running, and reduced power. The usual causes are a failed coil, a worn spark plug or boot, or a wiring fault at the coil.
Medium
Can I keep driving? Drivable, but the affected cylinder may misfire — sustained misfiring can overheat the catalytic converter, so avoid extended or hard driving until fixed.
Common symptoms
What you'll notice
- Check-engine light on (may flash during an active misfire)
- Rough idle or hesitation
- Misfire on one cylinder
- Reduced power on acceleration
Common causes
Most likely first
- Faulty ignition coil 'B' (secondary winding)Likely
- Worn spark plug or damaged plug boot on that cylinderCommon
- Coil connector or wiring faultCommon
- Carbon-tracked or arcing secondary circuitLess often
- ECM/PCM coil driver fault (less common)Less often
How to diagnose & fix
Work through it in order
- Identify which physical cylinder maps to coil 'B' for your engine.
- Inspect the coil, plug boot, and spark plug on that cylinder.
- Check the coil connector and wiring for damage or corrosion.
- Swap the suspect coil with a known-good one and see if the code follows it.
- Replace the faulty coil or plug, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P2305?+
Short trips are okay, but a misfiring cylinder dumps raw fuel into the exhaust and can damage the converter. Fix it soon and avoid hard driving.
Can I just clear P2305?+
It returns as soon as the coil circuit faults again. Repair or replace the coil or plug first.
Related codes
Often seen with P2305
Read & clear P2305 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX