P2305 — Ignition Coil "B" Secondary Circuit

OBD2 code P2305 flags a problem with the ignition system (ignition coil "B" secondary circuit). Short, gentle driving to a shop is usually possible. Common culprits: failed ignition coil or coil pack, damaged coil wiring or connector, moisture or oil in the spark plug wells.

powertrain (engine/transmission)

Is it safe to drive?

Drive with caution Drive with caution and avoid load. Ignition faults cause misfires that quickly overheat and destroy the catalytic converter; if the Check Engine Light flashes, stop and fix it first.

How to diagnose with an OBD scanner

  1. Read the code and freeze frame Connect an OBD2 scanner, confirm P2305 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
  2. Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
  3. Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the ignition system for damage, corrosion, chafing or poor contact.
  4. Subsystem check Swap the coil to another cylinder and see if the fault code follows it.
  5. Subsystem check Inspect spark plugs for wear, oil or carbon tracks and check plug gaps.
  6. Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P2305 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P2305 (parts and labor, USD, independent shop rates): Repair coil wiring or connector: $80–$250; Replace spark plugs: $90–$250; Replace an ignition coil: $150–$380. Overall, fixing P2305 usually costs between $80 and $380. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

Will P2305 clear itself?

Sometimes P2305 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

How much does it cost to fix P2305?

Repair coil wiring or connector — $80–$250; Replace spark plugs — $90–$250; Replace an ignition coil — $150–$380. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

What is the most common cause of P2305?

The most common causes are: failed ignition coil or coil pack, damaged coil wiring or connector, moisture or oil in the spark plug wells.

What are the symptoms of P2305?

Drivers most often notice: loss of power and jerking, Check Engine Light on, misfires under load or at idle, increased fuel consumption.

Is it safe to drive with P2305?

Drive with caution and avoid load. Ignition faults cause misfires that quickly overheat and destroy the catalytic converter; if the Check Engine Light flashes, stop and fix it first.

What does P2305 mean?

Behind P2305 is a specific failure in the ignition system: ignition coil "B" secondary circuit. The onboard computer stores it in the powertrain (engine/transmission) group after verifying the fault over repeated checks.

This code does not appear from a single bad reading: the module must see the fault condition repeat under defined operating conditions before it turns on the warning light. The freeze frame captured with P2305 — engine load, rpm, temperature, speed — tells you exactly when the problem occurs, so reproduce those conditions when testing.

What causes P2305?

  • faulty ignition control circuit in the ECM
  • worn spark plugs or wrong plug gap
  • damaged coil wiring or connector
  • moisture or oil in the spark plug wells
  • failed ignition coil or coil pack

Common symptoms of P2305

  • loss of power and jerking
  • Check Engine Light on
  • misfires under load or at idle
  • increased fuel consumption
  • hard starting, especially in damp weather

How to diagnose P2305

  1. Connect an OBD2 scanner, confirm P2305 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
  2. Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
  3. Visually inspect the wiring harness and connectors related to the ignition system for damage, corrosion, chafing or poor contact.
  4. Swap the coil to another cylinder and see if the fault code follows it.
  5. Inspect spark plugs for wear, oil or carbon tracks and check plug gaps.
  6. Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P2305 does not return.

How to fix P2305

Start with the cheapest and most common causes before replacing expensive parts:

  • Repair coil wiring or connector — $80–$250
  • Replace spark plugs — $90–$250
  • Replace an ignition coil — $150–$380

How much does it cost to fix P2305?

Repair cost depends on which component actually failed. Typical scenarios for P2305 (parts and labor, USD, independent shop rates):

  • Repair coil wiring or connector: $80–$250
  • Replace spark plugs: $90–$250
  • Replace an ignition coil: $150–$380

Overall, fixing P2305 usually costs between $80 and $380. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Can you drive with P2305?

Drive with caution and avoid load. Ignition faults cause misfires that quickly overheat and destroy the catalytic converter; if the Check Engine Light flashes, stop and fix it first.

Related OBD2 codes