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P0355 Generic (SAE)

Ignition Coil E Primary/Secondary Circuit

Updated 2026-10-02 · Ignition system & misfires

Severity
High
Typical repair cost
40 – 280 EUR
System
Powertrain

What it means

The ECM has detected a primary or secondary circuit fault in ignition coil E, the coil for cylinder 5 on five-, six- and eight-cylinder engines. The coil is not drawing the expected current when switched, or the feedback signal is missing, so cylinder 5 receives no reliable spark. Continuous misfire on this cylinder risks catalyst overheating and the ECM may disable that injector.

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Symptoms

  • Flashing check engine light under load
  • Misfire on cylinder 5 (P0305 stored)
  • Rough idle and engine vibration
  • Reduced power, especially on hills
  • Poor fuel economy and possible rotten-egg smell from the exhaust

Common causes

  1. Failed coil E (open primary, internal short or cracked insulation)
  2. Corroded or loose coil connector, common on rear-bank cylinders exposed to heat and moisture
  3. Damaged driver wire between ECM and coil E, often where the harness crosses the intake
  4. Fouled or wide-gapped spark plug on cylinder 5 overloading the coil
  5. Oil or coolant in the cylinder 5 plug well
  6. Faulty coil driver in the ECM or ignition module (rare)

How to diagnose

  1. Locate cylinder 5 from the engine's numbering diagram (bank and position vary between V6, V8 and inline-5 layouts) and confirm P0305 misfire counts live.
  2. Swap coil E with a known-good coil from another cylinder; if the fault code letter follows the coil, replace coil E and fit a new spark plug.
  3. With the connector unplugged and key on, check battery voltage on the supply pin and ground under 0.1 V; scope the driver pin while cranking for a clean 5 V or 12 V trigger pulse.
  4. Measure primary resistance of the suspect coil (typically 0.4-2 ohm) and compare it with the coils on neighbouring cylinders; a difference of more than 20 percent or an open reading means replace.
  5. Check continuity of the driver wire to the ECM (under 1 ohm) and insulation to ground and battery (over 10 kOhm); look for melted insulation where the harness passes near the exhaust manifold.
  6. Inspect the plug well and coil boot for oil, coolant or carbon tracks; fix any valve cover leak before fitting a new coil to avoid repeat failure.

Frequently asked questions

My engine has only four cylinders. Can P0355 appear?

No. Coil E corresponds to cylinder 5, so it only applies to engines with five or more cylinders. On a four-cylinder it would indicate a wrong ECM calibration or a scan tool decoding error.

Is coil E on bank 1 or bank 2?

It depends on the manufacturer's cylinder numbering. On many V6 engines cylinder 5 sits on bank 2 (the side without cylinder 1), but always confirm with the engine's layout diagram.

Related codes

P0305P0350P0353P0354P0356

Nearby codes in this group