Ignition and misfires

P0303 Misfire in cylinder 3

By: Diagno editorial team · Updated: 2026-10-15

P0303 means: Misfire in cylinder 3. The engine computer noticed that fuel in a cylinder sometimes doesn't burn. Don't drive until the car has been checked. The engine could be damaged. The most common repair costs about €60–120 in Estonia, depending on make and model.

Is it safe to drive?Don't driveDon't drive until the car has been checked. The engine could be damaged.

Spark plug replacement€60–120parts and labour in Estonia, depending on make and model

What it means

The engine computer noticed that fuel in a cylinder sometimes doesn't burn. The engine then runs rough and jerks.

What could be wrong

1Old spark plug · Spark plug replacement €60–120
2Faulty ignition coil · Ignition coil replacement €90–180
3Clogged or leaking injector · Injector replacement €200–400
4Air leak · Leak check and hose or gasket replacement €60–120
5Low compression · Engine mechanical repair (after compression test) €600–1200

What you can check yourself

Swap that cylinder's ignition coil with the neighbouring one and clear the code. If the misfire follows the coil, the coil is faulty. You can check the simple things yourself, but the repair is best done in a workshop.

How we fix it

We check the spark plugs and ignition coils
We check the injector and look for air leaks
If needed, we measure compression

Standard SAE description: Cylinder 3 Misfire Detected

This code usually comes with: Check engine lightSee what the light means →

Related symptoms: Car shaking or jerking

Want a definite answer?

Bring the car to our workshop in Estonia for diagnostics. We read the fault codes, test the sensors and tell you what is wrong. Repair price depends on the work involved, generally €45 per hour.

Book a diagnostic check

Questions

What does fault code P0303 mean?

Misfire in cylinder 3. The engine computer noticed that fuel in a cylinder sometimes doesn't burn. The engine then runs rough and jerks.

Can I drive with code P0303?

Don't drive until the car has been checked. The engine could be damaged.

How much does it cost to fix P0303?

It depends on the cause: spark plug replacement €60–120; ignition coil replacement €90–180; injector replacement €200–400. Prices include labour at €45/h, depending on make and model.

How is P0303 fixed?

We check the spark plugs and ignition coils. We check the injector and look for air leaks. If needed, we measure compression.

Based on AI combined with our hands-on workshop experience and knowledge. This information is general and prices are approximate (Estonian workshop rates). The same code can mean different things on different cars. Only an inspection of the car gives a definite answer.