P0356 medium Severity

P0356: Ignition Coil F Primary/Secondary Circuit Malfunction

May cause engine misfire, rough idle, reduced power and fuel efficiency; extended driving not recommended

Overview

P0356 Ignition Coil F primary/secondary circuit malfunction; common causes include bad ignition coil, wiring faults, connector issues, or PCM driver faults; symptoms include MIL illuminated, misfire, rough idle; diagnostic includes inspecting wiring, coil swap/test, PCM check

Common Symptoms

  • Check engine light illuminated
  • Engine misfire or rough idle
  • Reduced engine performance
  • Difficulty starting engine
  • Increased fuel consumption

Most Common Causes

Faulty ignition coil F (cylinder 6) high

Primary/secondary circuit malfunction often due to internal coil failure

Damaged wiring or poor connections in ignition coil circuit high

Open, short to ground, or short to voltage in coil driver wiring frequently triggers P0356

Corroded or loose connectors at coil or ECU medium

Connector corrosion or loose pins can interrupt signals

Faulty powertrain control module (PCM) coil driver medium

Less common but possible if wiring and coil test normal

Diagnostic Steps

  1. Read all stored DTCs and freeze frame data with a professional OBD-II scanner
    Expected: Identification of P0356 and any other related codes
    Interpretation: Verify P0356 is present and note any additional codes that may assist diagnosis
  2. Visually inspect ignition coil F (cylinder 6) and associated wiring/connectors
    Expected: No visible damage, corrosion, breaks, or loose pins
    Interpretation: If damage is observed, repair or replace affected parts
  3. Swap ignition coil F with another cylinder’s coil, clear codes, and test drive
    Expected: If code moves to the other cylinder, coil is likely faulty
    Interpretation: Code following coil confirms coil defect; if not, investigate wiring/ECU
  4. Check for proper voltage and driver signal at the coil connector using multimeter/oscilloscope
    Expected: AC Hz signal present during cranking/running and proper DC voltage supply
    Interpretation: Proper signals indicate coil driver and power supply are functioning
  5. Test continuity of wiring between PCM and ignition coil driver circuit
    Expected: Continuity within manufacturer spec
    Interpretation: Open or short indicates wiring harness repair needed
  6. If wiring and coil test good, evaluate PCM coil driver output or consider PCM testing
    Expected: PCM driver faults or irregular output
    Interpretation: Faulty PCM may require professional testing or replacement

Repair Solutions

Replace faulty ignition coil F easy
Estimated Cost: $80 - $300

Cost varies by vehicle and coil type

Repair or replace damaged wiring/connectors medium
Estimated Cost: $50 - $250

Depends on extent of harness damage

Replace corroded or loose connectors medium
Estimated Cost: $20 - $100

Connector kit costs vary

Replace or repair PCM if confirmed defective hard
Estimated Cost: $500 - $1500

PCM replacement is rare and should be confirmed by professional

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Replacing spark plugs instead of diagnosing ignition coil circuit
  • Assuming only the ignition coil is at fault without checking wiring/connectors
  • Ignoring concurrent codes pointing to wiring or PCM issues

Frequently Asked Questions

What is the definition of the P0356 engine code?

Ignition Coil F Primary/Secondary Circuit Malfunction is the standard definition for P0356. This diagnostic code is triggered when the ECU detects a problem in the Ignition.

How serious is the P0356 code?

This is a medium priority issue. May cause engine misfire, rough idle, reduced power and fuel efficiency; extended driving not recommended

What are the symptoms of P0356?

Drivers often report: Check engine light illuminated, Engine misfire or rough idle, Reduced engine performance when this code is present.

Potential causes for OBDII code P0356

This code is frequently triggered by: Faulty ignition coil F (cylinder 6), Damaged wiring or poor connections in ignition coil circuit, Corroded or loose connectors at coil or ECU.

What is the price difference for fixing P0356?

It depends on what needs to be fixed. Replace corroded or loose connectors repairs are cheaper (~$100), while Replace or repair PCM if confirmed defective repairs are on the higher end (~$1500).

Does code P0356 apply to Ford vehicles?

P0356 is not specific to any one brand. It can appear on Ford, Dodge, Toyota, Honda, Jeep, and other vehicles.

User Comments (0)

Share your experience or ask a question about this code.

Be the first to share your experience with P0356!