Ignition

P0350 — Ignition Coil Primary/Secondary Circuit Malfunction

Severity: medium Drive with care, to a shop

What P0350 means

P0350 means the engine control module detected a problem in the primary or secondary circuit of the ignition coil system. Normally the module switches current through the coil's primary winding, and the coil steps it up to high voltage for the spark plug. When the signal or current is out of range, the spark gets weak or disappears.

Symptoms

  • Check Engine light on
  • Engine misfires or runs rough
  • Loss of power or hesitation when accelerating
  • Unstable idle
  • Poor fuel economy
  • Hard starting or no start

Possible causes

  1. Failed ignition coil or coil pack
  2. Open, shorted or corroded wiring or connectors at the coil
  3. Blown fuse or faulty ignition relay
  4. Moisture or oil in the spark plug wells
  5. Worn spark plug breaking down
  6. Poor ground or battery voltage drops
  7. Faulty engine control module (rare)

How to diagnose

  1. Read codes and freeze-frame data and look for related misfire codes (P030x)
  2. Inspect coils, connectors and harness for damage, moisture, oil and heat marks
  3. Check the ignition fuses and relay
  4. Test battery voltage and verify clean, tight terminals and engine grounds
  5. Measure coil winding resistance and compare to the manufacturer spec
  6. Swap coils between cylinders to see whether the fault follows the coil
  7. Inspect spark plugs and gap, replace if worn
  8. Test wiring continuity to the module and check for the control signal; suspect the module last

Common fixes

  • Replace the faulty ignition coil or coil pack
  • Repair damaged wiring and connectors
  • Replace the blown fuse or ignition relay
  • Replace spark plugs and clean out the plug wells
  • Reprogram or replace the engine control module if everything else checks out

Questions and answers

Can I drive with a P0350 code?

Only a short distance with a light load. Misfires send unburned fuel into the catalytic converter and can destroy it.

What most often causes P0350?

Usually the ignition coil itself or damaged wiring or a connector leading to it. Check those first, along with the fuses.

Should I replace all the coils at once?

Not necessarily. Find the bad coil by testing first, though replacing a whole set can make sense if they are all old.

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.