P0351
UniversalIgnition Coil A Primary/Secondary Circuit Malfunction
Medium SeverityThe P0351 code indicates an issue with the electrical circuit for the ignition coil that supplies spark to cylinder A (typically cylinder 1). This malfunction prevents the ignition coil from firing correctly, leading to engine misfires and potentially reduced engine performance.
⚠️ Before You Begin (Safety First)
Always ensure the engine is off and cool before working on ignition components. Disconnect the battery's negative terminal to prevent electrical shock or damage to the vehicle's electrical system during inspection or repair.
Common Symptoms
- Check Engine Light illuminated (MIL)
- Engine misfire
- Rough idling
- Reduced engine power
- Poor fuel economy
- Engine hesitation or stalling
- Difficulty starting
Common Causes
- Faulty ignition coil for cylinder A
- Damaged wiring or connectors to the ignition coil
- Open or short circuit in the ignition coil primary or secondary circuit
- Faulty spark plug (can sometimes cause coil failure)
- Problem with the Engine Control Module (ECM) (rare)
Frequently reported on: Ford F-150 2004-2008, Honda Civic 2006-2011, Toyota Camry 2002-2006, Nissan Altima 2007-2012, Chevrolet Silverado 2007-2013
Diagnostic Steps
- Verify the code with an OBD-II scanner and clear it to see if it returns immediately.
- Visually inspect the ignition coil for cylinder A for any signs of damage, cracks, or burnt spots.
- Check the wiring harness and connector leading to the ignition coil for corrosion, fraying, or loose connections.
- If accessible, swap the ignition coil from cylinder A with a known good coil from another cylinder (e.g., cylinder B). If the misfire moves to cylinder B and triggers P0352, the coil is faulty.
- Replace the faulty ignition coil for cylinder A.
- Clear the code and test drive the vehicle to confirm the repair.
👨🔧 When to Call a Professional
If after checking basic connections and replacing the ignition coil, the code persists, or if multiple misfire codes appear, it's time to consult a professional mechanic. This could indicate a deeper electrical problem or an issue with the Engine Control Module (ECM).
Commonly Asked Questions
Can I drive with a P0351 code?
Driving with an active P0351 code is not recommended as it indicates an engine misfire. Prolonged driving can lead to catalytic converter damage, reduced engine performance, and potential drivability issues.
Is P0351 the same as a P0301?
P0351 specifically points to a primary/secondary circuit malfunction in the ignition coil for cylinder 1, while P0301 indicates a generic misfire in cylinder 1 without specifying the exact cause (which could be fuel, spark, or compression). P0351 often causes P0301.
How much does it cost to fix a P0351 code?
The cost to fix P0351 typically involves replacing the ignition coil, which can range from $75 to $200 for the part itself, plus an hour or two of labor if done by a professional (approximately $150-$300 total).
Can a bad spark plug cause P0351?
While a bad spark plug can cause a misfire (P0301), a P0351 code specifically indicates an issue with the ignition coil's electrical circuit, not the spark plug itself. However, a failing spark plug can put added stress on the coil, potentially leading to its premature failure.
What does 'Primary/Secondary Circuit' mean?
The primary circuit is the low-voltage side (12V) that charges the coil, controlled by the ECM. The secondary circuit is the high-voltage side that generates the high voltage spark for the spark plug. A malfunction can occur in either part of this electrical path.