Cylinder 4 misfire detected
Where to start
Misfire in cylinder 4. Checked by swapping the plug and coil with a neighbouring cylinder.
What the cylinder number gives you
The last digit names the cylinder: 4. 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 plug and the coil between cylinder 4 and a neighbour, clear the code and drive. If the fault follows the part, the part is to blame. If it stays on cylinder 4, the cylinder is: the injector, compression, a valve. This is the only way to tell one from the other without taking anything apart.
⚠️ Misfire is not only ignition. Check fuel trims: a large plus on one bank points to air, not to the plug. And do not clear the code before the swap — you lose the evidence.
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.