P0355 Code — Ignition Coil E Primary/Secondary Circuit Malfunction (Causes, Cost & DIY Fix) (2026)

Quick Check – 60‑Second Diagnosis

Your check‑engine light just illuminated and the scanner flashes P0355 – Ignition Coil E Primary/Secondary Circuit Malfunction. Before you reach for a wrench, perform a rapid visual sweep:

1. Connector check – Ensure the coil E plug is seated firmly. A loose pin can cause the PCM to read an abnormal voltage.
2. Wire condition – Look for cracked, burnt, or water‑soaked wires. Even a hairline crack can interrupt the primary circuit.
3. Battery health – A weak battery can cause low coil voltage, especially at idle. Measure the battery voltage; it should read at least 12.4 V with the engine off.

If any of these items are out of order, correct them, clear the code, and re‑scan. Often the problem resolves without further work.

Symptoms You’ll Notice While Driving

• Rough idle – The engine shakes at low RPMs because cylinder E isn’t firing correctly.
• Engine misfire – A misfire light (code P030X) often appears alongside P0355.
• Loss of power – Acceleration feels sluggish, especially under load.
• Increased fuel consumption – The ECU adds fuel to compensate for a weak spark.

These signs are most common on Toyota, Honda, Ford, and Chevrolet models that use a coil‑on‑plug (COP) system.

Safety Precautions Before You Begin

Following these precautions reduces the risk of electric shock, burns, or accidental fire.

What Triggers This Code (Root Causes)

Step‑by‑Step Diagnosis & Repair

The sequence below moves from the simplest, cheapest checks to the most involved repairs.

1. Visual Inspection (Already Covered)

Confirm that all connectors are tight, wires are intact, and the battery voltage is solid.

2. Read Live Data and Freeze‑Frame

• Connect an OBD‑II scanner.
• Navigate to the Ignition Coil E Voltage PID (often PID 0C0).
• Good result: Voltage stays within the manufacturer’s range (typically 5–12 V) with no spikes.
• Bad result: Voltage drops below spec or spikes erratically under load.

Capture the freeze‑frame snapshot for the exact RPM and load when the code set. This information helps you pinpoint whether the fault occurs at idle, under load, or both.

3. Test Primary Circuit Resistance

• Turn the ignition OFF and disconnect the coil E connector.
• Place multimeter leads on the primary terminals (marked A and B).
• Good: Resistance matches the service manual (usually a few ohms).
• Bad: Infinite reading (open circuit) or a value far above the spec, indicating internal coil damage.

4. Test Secondary Circuit Resistance

• Keep the connector off. Measure between the secondary terminal and engine ground.
• Good: Resistance falls within the manual’s range (often 0.5–2 Ω).
• Bad: Very high or infinite resistance (open) or near‑zero resistance (short).

5. Swap Coil E with a Known Good Coil

• Remove coil E and install a coil from another cylinder that you know works.
• Clear the code and drive the car briefly.
• Good: The P0355 disappears and a misfire moves to the swapped cylinder, confirming a bad coil.
• Bad: The code stays on P0355, pointing to wiring or PCM issues.

6. Inspect and Repair Wiring Harness

• Follow the coil‑E wire from the PCM to the coil. Look for chafed insulation, burnt spots, or loose crimps.
• Repair damaged sections with heat‑shrink tubing or replace the segment entirely.
• Perform a continuity test: low resistance to the coil and no shorts to ground.

7. Replace Ignition Coil E

• If the coil failed resistance tests or the swap moved the fault, install a new coil E.
• Torque the mounting bolts to the manufacturer’s spec (usually 8–12 Nm).
• Reconnect the harness, clear the code, and start the engine.

Result: Engine runs smoothly, no misfire codes, and live data shows proper voltage. If the code returns, the PCM driver may be at fault.

Cost Breakdown

Prices vary by region, model year, and parts source. The DIY route is viable for most makes if you have basic tools.

Make‑Specific Fixes for P0355

Toyota

Toyota’s 2.5 L 4‑cylinder engines (Camry 2015‑2022) route coil E wiring close to the exhaust manifold. Heat‑induced cracking of the wire’s insulation is a frequent cause. Re‑routing the wire away from the manifold and using a high‑temperature sleeve usually resolves the issue. Replacement coil cost averages $55.

Honda

Honda’s 1.5 L Turbo engines (Civic 2020‑2024) use a coil‑on‑plug design where each coil is a separate module. A cracked coil housing can let coolant seep into the primary circuit. Replace the coil (≈ $70) and verify the coolant leak is fixed to prevent recurrence.

Ford

Ford’s 2.7 L EcoBoost V6 (Explorer 2016‑2022) places coil E near the front‑wheel well, exposing it to road‑salt corrosion. Clean the connector with contact cleaner and apply dielectric grease. If the coil is bad, an OEM part runs $85.

Chevrolet

Chevy’s 3.6 L V6 (Malibu 2017‑2021) shares a common ground strap among the coils. A loose ground strap can cause the secondary circuit to read high resistance. Tighten the strap; if the problem persists, replace the coil pack (≈ $120).

Emissions Test Failure Impact

A misfiring cylinder raises unburned hydrocarbons in the exhaust. Most state emissions inspections will flag a “Failed – Misfire” result when P0355 is active. The vehicle may also trigger a “Failed – Catalyst Efficiency” warning because the catalytic converter works harder to oxidize excess fuel. Fixing the coil issue restores proper combustion, improves fuel economy, and helps the car pass the next emissions test.

Can You Still Drive With This Code?

Yes, you can keep the vehicle on the road, but expect:

• Rough idle and occasional stutter at low speeds.
• Reduced power when climbing hills or passing.
• Higher fuel consumption (typically 2‑4 % increase).
• Potential catalytic‑converter wear if the misfire persists for many miles.

The severity is medium: the engine will not seize, but prolonged operation can lead to long‑term emissions and component wear. If the car exhibits severe shaking, loss of power, or the check‑engine light flashes rapidly, stop driving and address the issue immediately.

Preventive Maintenance Tips

• Inspect coil wiring every 30 000 mi, especially on vehicles with coils near hot exhaust components.
• Replace spark‑plug boots that show cracking or oil contamination.
• Apply dielectric grease to coil connectors to keep moisture out.
• Run a regular OBD‑II scan during routine service to catch early voltage irregularities.
• Keep the battery terminals clean; a poor ground can masquerade as a coil problem.

When to Seek Professional Help

• All DIY tests (resistance, swap, wiring) are within spec, yet the code returns.
• The vehicle exhibits a flashing check‑engine light (multiple misfires per minute).
• You lack a multimeter or OBD‑II scanner capable of reading live data.
• The PCM driver is suspected; replacement requires re‑programming and specialized tools.

A qualified technician can perform a bench‑test of the PCM, re‑flash software, and verify that the coil driver circuitry is functioning correctly.

Frequently Asked Questions

Q: Does P0355 affect other cylinders? A: The code points to coil E only, but a faulty coil can cause the PCM to misinterpret signals from neighboring cylinders, leading to secondary misfire codes (P030X).

Q: Can a bad spark plug cause P0355? A: A worn plug can increase the load on the coil, but the PCM will usually set a misfire code (P030X). Replace plugs as part of routine maintenance, but focus first on the coil and wiring for P0355.

Q: Is it safe to clear the code without fixing the problem? A: The code will likely return after a few drive cycles. Clearing it merely masks the symptom and may cause the vehicle to fail an emissions test.

Q: How often should I replace ignition coils? A: OEM coils typically last 80 000‑100 000 mi. However, exposure to extreme heat, moisture, or corrosion can shorten their life dramatically.

Related DTC Pages

• Learn why P0354 – Ignition Coil D Primary/Secondary Circuit Malfunction can appear alongside P0355.
• Discover how P0352 – Ignition Coil C Primary/Secondary Circuit Malfunction differs and when to address both.

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