P0355 medium Severity

P0355: Ignition Coil E Primary/Secondary Circuit Malfunction

Check Engine Light, possible misfire on cylinder 5, rough idle, reduced power

Overview

Generic OBD-II trouble code indicating an electrical fault in the primary or secondary circuit of ignition coil E (often cylinder 5), with causes ranging from wiring issues and bad coil to PCM driver failure.

Common Symptoms

  • Check Engine Light illuminated
  • Engine misfire, especially on cylinder 5
  • Rough idle
  • Loss of power or hesitation under load

Most Common Causes

Faulty ignition coil E (cylinder 5) high

Internal short or open circuit in the coil can trigger this code.

Damaged/worn wiring or connectors for coil E high

Broken wires, corroded terminals, or loose connections frequently lead to P0355.

Primary circuit open or short to voltage/ground medium

Circuit discontinuity or incorrect voltage supply to coil driver may set the code.

Faulty Powertrain Control Module (PCM) driver for coil low

Rare but possible when the PCM cannot properly switch the coil circuit.

Diagnostic Steps

  1. Connect a professional OBD-II scanner and confirm P0355 is present
    Expected: Code P0355 stored; note freeze frame data if available
    Interpretation: Confirms the code and operating conditions when it set
  2. Inspect wiring harness and connector to ignition coil E for damage, corrosion, or loose fit
    Expected: No visible damage, secure connections
    Interpretation: If damaged/loose, repair and retest
  3. Measure resistance of coil E primary and secondary windings with multimeter
    Expected: Resistance within OEM specifications
    Interpretation: Out-of-spec indicates faulty coil
  4. Swap coil E with another known good coil (if applicable) and clear codes
    Expected: Code follows to new position or disappears
    Interpretation: Helps confirm coil vs wiring/PCM issue
  5. Check for proper voltage and ground at coil connector with ignition on
    Expected: Correct battery voltage and ground present
    Interpretation: Absence indicates wiring or PCM driver problem

Repair Solutions

Replace faulty ignition coil E easy
Estimated Cost: $50 - $150

Cost varies by vehicle and coil type

Repair or replace damaged wiring or connectors medium
Estimated Cost: $20 - $200

Depends on extent of harness damage

Replace PCM or reprogram PCM driver circuit hard
Estimated Cost: $500 - $1500

Only after confirming PCM failure; rare

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Replacing spark plugs or unrelated ignition components when the wiring or coil is at fault

Frequently Asked Questions

Can you explain the meaning of P0355?

The P0355 code stands for Ignition Coil E Primary/Secondary Circuit Malfunction. This generally indicates an issue with the Ignition system.

Should I stop driving if I have P0355?

With a severity level of medium, check Engine Light, possible misfire on cylinder 5, rough idle, reduced power

What happens when the P0355 code is active?

Drivers often report: Check Engine Light illuminated, Engine misfire, especially on cylinder 5, Rough idle when this code is present.

Why is my car throwing a P0355 code?

The most common causes are: Faulty ignition coil E (cylinder 5), Damaged/worn wiring or connectors for coil E, Primary circuit open or short to voltage/ground.

Repair cost breakdown for P0355

Expect to pay around $150 if the issue is a Replace faulty ignition coil E, but up to $1500 if the Replace PCM or reprogram PCM driver circuit needs replacement.

Is the P0355 code specific to Mercedes?

This is a universal code. You might see P0355 on Ford, Chevrolet, Toyota, Honda, Nissan, or any other OBD-II vehicle.

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