FixItFor.Us
P codepowertrainHigh severity

P035BIgnition Coil "N" Primary/Secondary Circuit

The PCM has detected a fault in the primary or secondary circuit of ignition coil "N", which fires cylinder 14 on engines with fourteen or more cylinders.

Definition

Each coil-on-plug primary circuit is switched by the PCM and monitored for correct voltage feedback during every firing event. P035B sets when the coil "N" (cylinder 14) circuit shows an open, short to ground or voltage, or absent feedback, indicating the coil cannot fire reliably. Symptoms include a cylinder 14 misfire, rough idle, reduced power, and a steady or flashing MIL; prolonged misfiring dumps raw fuel into the exhaust and can destroy the catalytic converter. This code applies only to high-cylinder-count engines such as V16s.

Common causes

  • Failed ignition coil for cylinder 14
  • Corroded, loose, or damaged coil connector
  • Open or shorted wiring in the coil control or power feed circuit
  • Blown ignition coil fuse or faulty ignition relay
  • Poor coil or engine ground
  • Defective PCM coil driver (least common)

Common misdiagnoses

  • Spark plugs replaced when the primary circuit wiring is at fault
  • Fuel injector replaced for an ignition-caused dead cylinder
  • PCM replaced without checking the harness and connector first
  • Complete coil set replaced when a single circuit fault exists

Troubleshooting steps

  1. 1.Swap the suspect coil with a known-good cylinder

    If the code moves with the coil to the new cylinder's designator, replace the coil; if it stays on cylinder 14, the fault is in the wiring or PCM.

  2. 2.Inspect the connector and coil boot

    Check for bent or backed-out terminals, corrosion, oil contamination, and carbon tracking inside the boot.

  3. 3.Confirm the power feed

    Verify battery voltage at the coil supply pin with the key on; check the shared coil fuse and relay if voltage is missing.

  4. 4.Measure primary winding resistance

    Compare against spec (typically about 0.4-2.0 ohms); an open winding confirms coil failure.

  5. 5.Scope the PCM trigger signal

    Verify the primary control circuit is being switched during cranking; no trigger with intact wiring indicates a PCM driver fault.

  6. 6.Wiggle-test the harness

    Manipulate the coil sub-harness while watching for the misfire or code to reappear, isolating an intermittent open.

Related codes