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DTC codes / Ford codes / P1352

P1352 · FordIgnition Coil A Primary Circuit Fault

P1352 on Ford vehicles means the powertrain control module (PCM) has detected an electrical fault in the primary circuit of ignition coil A, which is the low-voltage side that the PCM uses to trigger the coil. The PCM monitors the coil driver circuit for abnormal voltage or current behavior and sets this code when the signal does not match expected values during engine operation.

SystemPowertrain
Code typeFord specific
SeverityMedium
Fix difficultyIntermediate
AreaIgnition system and misfire

Symptoms you may notice

  • Often no symptoms besides the warning light, especially if the fault is intermittent
  • Engine misfire or rough running, particularly under load or acceleration
  • Noticeable loss of power and reduced fuel economy
  • Shaking or vibration from the engine bay that worsens with engine speed
  • Difficulty starting or a stall shortly after startup in more severe cases
  • 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 A with an open or shorted primary winding
  2. Damaged or corroded wiring harness and connector at coil A
  3. Poor ground connection for the coil or engine block
  4. Failed ignition coil driver inside the PCM (less common but possible)
  5. Contamination such as oil or coolant soaking the coil and connector
  6. Aftermarket or incorrect coil installed that does not meet Ford specifications

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data to confirm when P1352 sets and whether other misfire codes are present
  2. Visually inspect coil A, its connector, and the harness for corrosion, chafing, or oil contamination
  3. Measure primary coil resistance with a multimeter and compare to Ford specifications for the engine
  4. Check for battery voltage at the coil connector with the key on and verify the ground circuit with a voltage drop test
  5. Swap coil A with a known-good coil from another cylinder and see if the fault follows the coil or stays with the cylinder
  6. Use an oscilloscope or a noid light to check the PCM driver signal at the coil connector during cranking and running
  7. If the driver signal is missing and all wiring checks pass, diagnose the PCM driver circuit before replacing the PCM

What Ford technicians check before replacing coil A

  • A coil that ohms out perfectly on the bench can still fail under heat and load, so a resistance check alone does not clear the coil of suspicion.
  • Oil leaking from a failed valve cover gasket or spark plug tube seal is a common hidden cause on Ford engines, soaking the coil boot and primary connector.
  • The PCM driver for coil A can be damaged by a shorted coil, so replacing the coil without checking the driver circuit risks repeating the failure.
  • P1352 can be set by a poor engine ground even when the coil and wiring test good, because the PCM compares driver voltage against a reference that depends on a clean ground.
  • Aftermarket coils with incorrect primary resistance are a frequent cause of repeat P1352 codes on Ford vehicles, so use a coil that meets the original specification.

Can I keep driving with P1352?

You can drive cautiously to a repair shop if the engine runs smoothly and the check engine light is steady, but avoid heavy acceleration and long trips. If the light is flashing or the engine misfires badly, stop driving because unburned fuel can overheat and destroy the catalytic converter.

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 Ford vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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