P2305 indicates the powertrain control module (PCM) has detected an abnormality in the secondary (high-voltage) circuit of ignition coil B, typically corresponding to cylinder 2. This code sets when the expected ionization current or secondary voltage feedback is missing, erratic, or outside calibrated thresholds during combustion events.
Internal short or open in the coil secondary winding prevents generation of sufficient spark voltage, disrupting the ionization current the PCM monitors.
Excessive electrode gap, carbon tracking, or internal failure creates abnormal secondary circuit resistance that the PCM interprets as a coil circuit fault.
Cracked insulation, carbon tracking, or open circuits in the spark plug boot or wire prevent high voltage from reaching the plug, altering secondary circuit feedback.
Corroded, bent, or moisture-contaminated pins in the coil connector, or chafed wiring affecting the coil control or monitoring circuits, can trigger this code.
A rare internal driver or sensing circuit fault within the PCM may incorrectly report a secondary circuit malfunction when the coil and wiring are serviceable.
No. Continuous driving with an active misfire can overheat and permanently damage the catalytic converter due to raw fuel entering the exhaust system.
Almost never. While a faulty PCM can theoretically set this code, ignition coils, spark plugs, or wiring faults are the cause in the vast majority of cases. The PCM should be the last component suspected.
It refers to the high-voltage side of the ignition coil that delivers spark to the plug. The PCM monitors this circuit for proper ionization current; deviations indicate insufficient spark or coil failure.
While coil replacement often resolves the issue, proper diagnosis prevents unnecessary parts replacement. A failed spark plug or boot can damage a new coil, so these should be inspected first.