P0358 medium Severity

P0358: Ignition Coil H Primary/Secondary Circuit Malfunction

Possible misfire on cylinder 8, rough idle, reduced power and drivability depending on severity

Overview

P0358 ignition coil H (cylinder 8) primary/secondary circuit malfunction causes diagnostics and repair

Common Symptoms

  • Check Engine Light illuminated
  • Rough idle
  • Misfire on cylinder 8
  • Reduced engine power or hesitation
  • Increased fuel consumption

Most Common Causes

Faulty ignition coil (coil H / cylinder 8) high

Ignition coil internal short or open causes primary/secondary circuit fault

Open or short in ignition coil wiring harness high

Broken, chafed wiring or poor connection in the circuit to the coil

Poor or corroded connector at the coil medium

Loose pins or corrosion in the connector can raise resistance and trigger fault

Faulty PCM/ECM coil driver low

Rare; consider only after all wiring and coil checks fail

Faulty spark plug stressing the coil circuit low

Severely worn or fouled spark plug can mimic coil circuit problems

Diagnostic Steps

  1. Scan vehicle OBD‑II system
    Expected: Retrieve P0358 and any accompanying codes
    Interpretation: Confirms specific ignition coil circuit fault
  2. Perform visual inspection of coil H wiring and connectors
    Expected: Check for damaged wires, corrosion, loose connections
    Interpretation: Damage indicates possible wiring fix
  3. Test ignition coil primary and secondary circuit with multimeter
    Expected: Resistance within manufacturer spec
    Interpretation: Out‑of‑spec indicates coil failure
  4. Swap coil H with another cylinder's coil (where applicable)
    Expected: Code follows swapped coil
    Interpretation: Confirms coil as root cause
  5. Check continuity of wiring from PCM to coil connector
    Expected: Continuity present, no shorts to ground or voltage
    Interpretation: Opens or shorts identify wiring issues
  6. If wiring and coil test good, test PCM coil driver output (advanced)
    Expected: Proper PCM signal pattern
    Interpretation: Lack of signal suggests PCM fault

Repair Solutions

Replace faulty ignition coil H medium
Estimated Cost: $50 - $300

Common repair; costs depend on vehicle and labor

Repair or replace damaged wiring harness/connectors medium
Estimated Cost: $50 - $150

Includes cleaning corroded terminals

Replace PCM/ECM coil driver (rare) hard
Estimated Cost: $300 - $800

Only after verifying all other causes are eliminated

Replace spark plug on cylinder 8 easy
Estimated Cost: $10 - $50

Good practice when servicing ignition coil

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Misinterpreting related misfire codes (e.g., P0308) as separate issues without checking coil circuit
  • Replacing spark plugs alone expecting to fix P0358
  • Assuming all coils are faulty when only coil H is faulty

Frequently Asked Questions

Can you explain the meaning of P0358?

Ignition Coil H Primary/Secondary Circuit Malfunction is the standard definition for P0358. This diagnostic code is triggered when the ECU detects a problem in the Ignition.

Should I stop driving if I have P0358?

This is a medium priority issue. Possible misfire on cylinder 8, rough idle, reduced power and drivability depending on severity

Symptoms associated with DTC P0358

Common symptoms include: Check Engine Light illuminated, Rough idle, Misfire on cylinder 8. You might also notice the Check Engine Light is on.

What causes the P0358 code?

It can be caused by several factors, most notably: Faulty ignition coil (coil H / cylinder 8), Open or short in ignition coil wiring harness, Poor or corroded connector at the coil.

What is the price difference for fixing P0358?

Expect to pay around $50 if the issue is a Replace spark plug on cylinder 8, but up to $800 if the Replace PCM/ECM coil driver (rare) needs replacement.

Does code P0358 apply to Toyota vehicles?

This is a universal code. You might see P0358 on Ford, Chevrolet, Toyota, Honda, Nissan, or any other OBD-II vehicle.

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