Ignition

P0359 — Ignition Coil I Primary/Secondary Circuit Malfunction

Severity: medium Drive with care, to a shop

What P0359 means

P0359 means the engine control module detected a problem in the primary or secondary circuit of ignition coil "I", which is typically the coil for cylinder 9 on V10 and V12 engines. Normally the module switches current through the coil's primary winding on and off, and the coil steps this up to fire the spark plug. When the expected signal or current is missing or out of range, the code is stored and the check engine light comes on.

Symptoms

  • Check engine light on or flashing
  • Intermittent or constant misfire
  • Rough idle
  • Hesitation or loss of power
  • Worse fuel economy
  • Fuel smell from the exhaust

Possible causes

  1. Failed ignition coil I
  2. Open, shorted or corroded wiring or connector at the coil
  3. Poor power supply, such as a blown fuse or bad relay
  4. Poor ground connection
  5. Faulty coil driver inside the PCM
  6. Worn or wrong spark plug overloading the coil

How to diagnose

  1. Scan for codes and freeze frame data, and look for related misfire codes (P03xx)
  2. Identify which cylinder coil I serves using the wiring or service info for your engine
  3. Inspect the coil connector and harness for heat damage, corrosion or chafed insulation
  4. Check the fuse and relay that feed the coils
  5. Measure supply voltage and ground at the coil connector
  6. Swap the coil with a neighboring one and see whether the fault follows it
  7. Test coil winding resistance and inspect the spark plug
  8. Check the PCM control signal with a scope or noid light

Common fixes

  • Replace the ignition coil
  • Replace the spark plug along with the coil if worn
  • Repair the wiring or connector
  • Replace the blown fuse or faulty relay
  • Reflash or replace the PCM if the coil driver has failed

Questions and answers

What does P0359 mean?

It indicates a fault in the primary or secondary circuit of ignition coil I. The PCM isn't seeing the expected response, so that cylinder may misfire.

Can I drive with a P0359 code?

Only briefly and gently. Misfires can damage the catalytic converter, and a flashing check engine light means you should stop driving.

How do I tell if it's the coil or the wiring?

Swap the coil with a neighboring one and clear the code. If the fault moves with the coil, replace it. If it stays put, look at the connector, wiring or PCM.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.