Single Cylinder Misfire (Cylinder Not Specified)
What it means
The engine computer has detected that one cylinder is not firing properly, but it could not identify which one. The technician has to find that cylinder, then look for the cause as with any single-cylinder misfire: the spark plug, ignition coil or injector.
Related lights
Dashboard lights that may come on with this code.
Symptoms4
- Steady engine shaking at idle.
- Weak acceleration.
- Check engine light on, possibly flashing during a severe misfire.
- Smell of unburned fuel from the exhaust.
Possible causes6
- Damaged spark plug in one cylinder.
- Weak ignition coil on one cylinder.
- Clogged or faulty injector in one cylinder.
- Damaged wiring or connector at a coil or injector.
- Low compression in one cylinder.
- Inaccurate crankshaft position (CKP) sensor signal that prevents the computer from identifying the cylinder (less common).
How to diagnose5
- Read all stored codes and check per-cylinder misfire data on the scan tool if it supports it.
- Listen to the engine and briefly unplug each coil with the engine running; the cylinder whose disconnection makes no difference is the dead one.
- Once the cylinder is found, inspect its plug and swap its coil with another cylinder.
- Check the injector of the suspect cylinder and its connector.
- If no single cylinder stands out, check the CKP sensor signal and the tone ring, and have a compression test done.
How to fix6
- Replace the damaged spark plug, or the full set if it is due.
- Replace the faulty ignition coil.
- Repair the wiring or connector.
- Clean or replace the faulty injector.
- Replace the CKP sensor if its signal is proven faulty.
- Clear the codes, road test and confirm the code does not return.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
In the Saudi market: SAR 150–1,500 (≈ USD 40–400)
Our prices come from the Saudi market, converted at a fixed rate (SAR 3.75 per USD). Prices in your country may differ a lot, so we show the cost level.
The low end is a plug or coil once the cylinder is found; the cost rises with an injector or CKP sensor, and diagnosis takes longer here because the computer did not name the cylinder.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026
Frequently asked questions
How do I find the bad cylinder if the computer does not name it?
Some scan tools show a misfire counter per cylinder. If not, a technician unplugs the coils one at a time; the cylinder that makes no difference when unplugged is the one not working.
What is the difference between P0314 and P0300?
P0300 means the misfire moves between several cylinders. P0314 means the computer sees only one cylinder misfiring but does not know its number, so the cause is usually a single part.
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