Ignition Coil B Primary/Secondary Circuit Malfunction

What You Might Notice

• Check Engine Light illuminated
• Engine misfire or rough idle
• Intermittent misfiring
• Loss of power during acceleration
• Decreased fuel economy

Most Common Causes

1. 1

   Bad ignition coil

   Coil B has failed internally or externally preventing proper spark generation.

2. 2

   Loose or corroded connector

   Poor electrical connection at coil B connector blocks signal transmission.

3. 3

   Wiring short or open circuit

   COP driver circuit has broken wire or short to voltage/ground.

4. 4

   Faulty PCM

   Engine control module unable to drive ignition coil B properly.

How to Diagnose It

1. 1

   Check Bad ignition coil — Coil B has failed internally or externally preventing proper spark generation.

2. 2

   Check Loose or corroded connector — Poor electrical connection at coil B connector blocks signal transmission.

3. 3

   Check Wiring short or open circuit — COP driver circuit has broken wire or short to voltage/ground.

4. 4

   Check Faulty PCM — Engine control module unable to drive ignition coil B properly.

How to Fix It

1. 1

   Replace ignition coil B

   Swap faulty coil with OEM or quality aftermarket unit.

   Ignition Coil B↗
2. 2

   Inspect and reseat connector

   Clean corrosion, repair broken locks, and ensure tight connection at coil.

3. 3

   Check and repair wiring

   Inspect COP driver circuit for shorts, opens, or damaged insulation.

   Wiring Harness If Damaged↗
4. 4

   Test and replace PCM

   Verify PCM output with scope; replace if defective.

   Powertrain Control Module↗