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P035DIgnition Coil "P" Primary/Secondary Circuit

The PCM has detected a fault in the primary or secondary circuit of ignition coil "P", which fires cylinder 16 on sixteen-cylinder engines.

Definition

The PCM switches the primary side of each coil-on-plug coil and monitors feedback to verify each firing event on the primary and secondary circuits. P035D sets when the coil "P" (cylinder 16) circuit shows an open, a short, or no firing feedback, so cylinder 16 loses spark. Symptoms include a dead or intermittent misfire on cylinder 16, rough idle, reduced power, and a steady or flashing MIL, with sustained misfire risking catalytic converter damage. This designator applies only to sixteen-cylinder engines.

Common causes

  • Failed cylinder 16 ignition coil
  • Corroded or damaged coil connector terminals
  • Open or shorted primary circuit wiring
  • No battery feed to the coil from a blown fuse or bad relay
  • Poor ground connection at the coil bank
  • Internal PCM driver failure (least common)

Common misdiagnoses

  • Spark plugs replaced when the circuit itself is faulty
  • Fuel injector replaced for what is an ignition fault
  • PCM replaced without proving the trigger signal is missing
  • Full coil set replaced for one bad circuit

Troubleshooting steps

  1. 1.Swap the coil to another cylinder

    If the coil-circuit code follows the coil to its new position, replace the coil; if it stays on cylinder 16, test the harness.

  2. 2.Inspect connector and boot condition

    Check for spread terminals, corrosion, oil in the plug well, and carbon tracking on the boot.

  3. 3.Confirm power and ground at the coil

    Battery voltage should be present key-on on the feed pin, with less than 0.1 V drop on the ground side while cranking.

  4. 4.Measure the primary winding

    Compare resistance to spec (commonly 0.4-2.0 ohms); open or shorted readings confirm the coil.

  5. 5.Scope the control circuit

    Verify the PCM primary trigger while cranking; a clean trigger with no spark condemns the coil, no trigger with good continuity implicates the PCM.

  6. 6.Road-test after repair

    Clear codes and confirm zero misfire counts on cylinder 16 in mode 6 or the misfire counter PID under load.

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