Ignition coil, cylinder 5 — circuit malfunction
Where to start
The coil circuit of cylinder five. A fifth cylinder belongs to inline fives and V6s — engines where the coils sit on both sides, so the «neighbouring cylinder» for a swap must be taken from the same bank. If the code appears together with P0356 or P0357, look not at the coils but at what the bank shares: the coil supply and that bank's earth. The partner code is P0305.
What the cylinder number gives you
The last digit names the cylinder: 5. That is the most useful thing in this code — it turns a search across the whole engine into a check of one cylinder.
Swap and watch. Move the coil between cylinder 5 and a neighbour, clear the code and drive. If the fault follows the part, the part is to blame. If it stays on cylinder 5, the cylinder is: the injector, compression, a valve. This is the only way to tell one from the other without taking anything apart.
⚠️ This code is about the CIRCUIT, not the spark: the connector and the wire come before the coil itself. A coil is often replaced when the trouble was a corroded contact.
How to put together a report a mechanic will actually read
How the code is built
All codes in «Ignition system and misfires»
How the app helps
CarScan reads this code from your car through an OBD-II adapter, shows whether it is active now or only stored, names the module that reported it, and puts it into a plain-text report for your mechanic.