P0355 Code: Ignition Coil E Primary/Secondary Circuit
Coil E, the coil for cylinder 5, has an electrical fault. Only engines with five or more cylinders have one.
At a glance
Severity: Moderate
- Meaning
- Ignition Coil E Primary/Secondary Circuit
- System
- Ignition & Misfire · Powertrain
- Safe to drive?
- With caution
- Typical repair cost
- $80–$600
- DIY difficulty
- Moderate
P0355 means the engine computer's check of its fifth coil output failed: when it switched coil E, the primary current or the feedback pulse did not look right. Only inline fives, sixes, V6s and V8s have a coil E, so a four-cylinder should never set this code. Where cylinder 5 sits varies a lot. On a Ford V8 it is the front cylinder on the driver side and easy to reach, while on transverse Toyota and GM V6s it is at the far end of the rear bank under the intake plenum. Coil E faults are often heat-related: a coil whose insulation is breaking down works when cold and drops out once the engine bay is hot, and the freeze-frame data usually shows that pattern.
Can I keep driving? The engine will run on the remaining cylinders, but avoid long trips, towing and hard acceleration. If the light starts flashing, pull over: the catalytic converter is overheating.
How to read P0355
- P Powertrain
- 0 Generic (SAE)
- 3 Ignition / misfire
- 55 Specific fault
Symptoms
- Miss that appears only after 15 to 20 minutes of driving, once the engine is hot
- Check-engine light with P0305, sometimes flashing on hills
- Vibration felt through the seat at idle in Drive
- Loss of pull when towing or climbing
- On waste-spark V6 and inline-six engines, cylinder 2 misfires along with cylinder 5
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Coil E is breaking down internally, typically failing once hot
- Coil E connector with loose terminals or a broken latch
- Coil harness insulation baked brittle near the exhaust manifold or turbocharger
- Oil in the cylinder 5 plug well from a leaking valve cover gasket
- Shared waste-spark coil for cylinders 2 and 5 has failed (older GM V6 packs, Jeep 4.0L coil rail)
- Feed or ground problem shared by the coils on cylinder 5's bank
- Coil E driver in the engine computer has failed
Diagnosis step by step
Confirm the engine has a coil E and find it
Only engines with five or more cylinders have coil E. On a Ford V8 it is the front driver-side coil, on a GM V8 the third from the front on the driver side, on a transverse Ford or Honda V6 the middle of the front bank, and on a transverse Toyota or GM V6 the far end of the rear bank. On an inline six it is the second from the back.
Tools: Flashlight
Read the freeze frame
Look at coolant temperature, engine speed and load at the moment the code set. A fault logged at full operating temperature after a long drive points to a coil breaking down when hot. A fault logged on a cold start points more to moisture or a loose connection.
Tools: OBD-II scanner
Heat-test the coil
With the engine idling and the cylinder 5 misfire counter on the scan tool, gently warm coil E with a heat gun, keeping it off the connector and plastic covers. If the misses start as it warms, the coil is failing. On a hot engine, a quick blast of freeze spray that makes the misses stop proves the same thing.
Tools: OBD-II scanner, Gloves
Check for oil and heat damage
Pull coil E and look for oil in the well and on the boot. Follow its harness back and look for insulation that has gone hard, cracked or shiny where it passes near the exhaust manifold or turbo heat shield. Heat-damaged wiring can open up only when it expands.
Tools: Flashlight
Look at the pattern with other cylinders
If cylinder 2 is also misfiring on an engine with a three-coil pack or a coil rail, the shared coil for 2 and 5 is the part to replace. If several coils on the same bank of a V8 show circuit codes, test that bank's feed and ground before buying coils.
Tools: OBD-II scanner, Multimeter
Replace and check the plug
Fit an original-equipment quality coil and inspect plug 5 while it is accessible. A plug with a worn center electrode raises the voltage the coil has to make, and that heat and stress are what ended the old coil.
Tools: Spark plug socket, Torque wrench
Where the parts are
- 1Ignition coil
- 2Spark plug
- 3Fuel injector
- 4Camshaft sensor
- 5Crankshaft sensor
- 6Engine computer (ECM)
- 7Intake manifold
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Replace coil E (easy access, for example Ford V8 front driver side) | Yes | $80–$250 |
| Replace coil E on a rear bank under the intake plenum | No | $250–$600 |
| Replace three-coil pack or coil rail (cylinders 2 and 5 shared) | Yes | $150–$450 |
| Repair heat-damaged coil harness section | No | $100–$350 |
| Valve cover gasket to stop oil in the well | No | $180–$550 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Field data
| Ford | 2 | Escape Hybrid, F-150 |
|---|
Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.
Emissions / smog test impact
Will fail
P0355 is an emission-related fault that keeps the check-engine light on, so the car fails an OBD-II smog check. Because heat-related coil faults can be intermittent, make sure the code has not returned and the monitors are ready before you go.
Frequently asked questions
My car has four cylinders but shows P0355. How?
A four-cylinder engine has no coil E. Check that the code isn't really P0335 (crankshaft sensor) or P0305, which are easy to misread on a small display, and repeat the scan with a better tool.
Why does the miss only happen when the engine is hot?
Coils fail from the inside out. As the insulation between the windings ages it starts leaking current once it expands with heat. The coil works fine cold and fails after the engine bay has heated up, which is exactly what a heat-gun test reproduces.
Where is cylinder 5 on a Ford V8?
Ford numbers the passenger bank 1 to 4 and the driver bank 5 to 8, front to back. So cylinder 5 is the front cylinder on the driver side, usually one of the easiest coils to reach.
Should I replace coil E and cylinder 2's coil together?
Only if they are in the same housing, as on three-coil packs and coil rails where cylinders 2 and 5 share a coil. On coil-on-plug engines they are separate parts and there is no reason to replace cylinder 2's coil.