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DTC codes / P03xx · Ignition system and misfire / P0350

P0350Ignition Coil Primary/Secondary Circuit

P0350 is a generic ignition system code indicating that the engine control module has detected an abnormal condition in the primary or secondary circuit of an ignition coil that is not assigned to a specific cylinder. The computer monitors coil dwell time and circuit continuity, and when the signal does not match expected values, it sets this code to alert the driver of a potential misfire or ignition failure.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaIgnition system and misfire

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Engine misfire, rough idle, or hesitation during acceleration
  • Reduced engine power or a limp mode condition
  • Difficulty starting or a no-start condition in severe cases
  • Poor fuel economy or increased emissions
  • A flashing check engine light if the misfire is severe enough to damage the catalytic converter

Common causes, most likely first

  1. Faulty ignition coil with an open or shorted primary or secondary winding
  2. Damaged or corroded wiring or connector at the ignition coil
  3. Failed ignition control module or driver circuit inside the engine control module
  4. Poor ground connection for the ignition coil or engine
  5. Spark plug wear or incorrect gap causing excessive secondary resistance
  6. Electrical interference or a short in a related circuit sharing the same harness

How to diagnose and fix it

  1. Perform a visual inspection of the ignition coil, connectors, and wiring for signs of damage, corrosion, or loose connections
  2. Use a scan tool to check for related misfire codes and freeze-frame data to identify which cylinder or coil is affected
  3. Test the ignition coil primary and secondary resistance with a multimeter and compare to manufacturer specifications
  4. Check for power and ground at the coil connector with the key on and during cranking using a test light or multimeter
  5. Inspect the spark plugs and replace if worn or fouled, as they can stress the coil
  6. Swap the suspect coil with a known-good one from another cylinder to see if the misfire moves
  7. If the coil and wiring test good, diagnose the ignition control circuit from the engine control module to the coil, including checking for a faulty driver

What a P0350 Really Tells You

  • P0350 is often a generic code that points to a problem in the ignition coil circuit as a whole, but many vehicles set it when a specific coil driver fails, so always check for companion codes like P0351 through P0358 that pinpoint the cylinder.
  • A weak battery or charging system issue can cause low voltage to the ignition coils, triggering P0350 without any faulty coil, so verify battery and charging system health before replacing parts.
  • The code can be set by a faulty spark plug or spark plug wire (on engines that use them) that increases secondary resistance, overloading the coil and causing the primary circuit to draw excessive current.
  • Intermittent wiring problems, such as a chafed wire that shorts only when the engine moves, may not show up in a static resistance test; a wiggle test while monitoring coil operation with a scope or scan tool is often necessary.
  • Replacing an ignition coil without addressing a worn spark plug or faulty ignition cable can lead to repeat coil failure, so always inspect the entire secondary ignition system.

Can I keep driving with P0350?

If the check engine light is steady and the engine runs smoothly, you can drive cautiously to a repair shop, but avoid heavy acceleration or long trips. If the light is flashing or the engine misfires severely, stop driving immediately to prevent catalytic converter damage and further engine harm.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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