The coil's secondary circuit is not producing a proper spark event on cylinder 1.
P2301 — also written P23O1, P 2301, 2301 — is the OBD-II code for ignition coil 'a' secondary circuit insufficient ionization. Same code, same fix: this page covers every spelling of it.
P2301 is a engine fault code, typically costing £70–£350 to put right in a UK garage.
What causes P2301?
- Failed ignition coil
- Worn spark plug with an over-wide gap
- Cracked coil boot arcing to the head
- Damp in the plug well
How P2301 is fixed
- Fit new plugs to the correct gap
- Replace the coil and boot
- Dry and reseal the plug wells
P2301 repair cost in the UK
Most P2301 repairs land between £70–£350 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Can you drive with P2301?
Drive gently. A flashing light means the catalytic converter is at risk.
Urgency: high.