Ignition Coil A Primary Control Circuit Low
The primary control circuit of ignition coil A reads a voltage below the expected level — usually a short to ground on the primary driver wire or a low-resistance fault in the coil primary winding. Coil A cannot build a normal charge, so the cylinder it fires misfires, especially under load. Causes: short to ground in the primary wiring, an internal coil primary fault, or a faulty ECU/igniter driver.
Affected components
- Ignition coil
- Coil driver
- Ignition wiring
Common causes
- High likelihood: Internal coil short
- Medium likelihood: Primary wire shorted to ground
- Low likelihood: Connector pins corroded - high contact resistance
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
Related codes
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.