What does code P0303 mean?

P0303 — Misfire in cylinder 3. Consistent engine shake, most noticeable on cold start. Belongs to the powertrain.misfire system. Severity: warning.

What are the common causes of P0303?

Cylinder 3 spark plug — replace as a set of four; Cylinder 3 ignition coil; Cylinder 3 injector; Cylinder 3 compression — measure with a gauge; Wiring/connector to cylinder 3 — corrosion, chafing

Can I drive with code P0303?

Limited: reaching the nearest workshop is fine, but avoid long trips. May progress into a more serious fault.

How do I diagnose P0303?

Read the code and freeze-frame with a scanner, check related-system errors, inspect the components listed (wiring, connectors, sensors). See the "How to diagnose" section above for the full step-by-step.

How do I clear code P0303?

The code can be cleared via an OBD-II scanner (e.g. ELM327 + the Car Diagnostics app): plug the adapter into the OBD port, go to Errors → Clear. If the underlying cause isn't fixed, the code will return within a few drive cycles.

OBD-II Code P0303 — Car Diagnostics Platform

What it means

Common causes

Cylinder 3 spark plug — replace as a set of four
Cylinder 3 ignition coil
Cylinder 3 injector
Cylinder 3 compression — measure with a gauge
Wiring/connector to cylinder 3 — corrosion, chafing
Intake manifold crack near cylinder 3
Burnt valve in cylinder 3

How to diagnose

01
Read all stored and pending codes with an OBD-II adapter — get the full picture, not just the one code.
02
Capture freeze-frame data (RPM, coolant temperature, engine load) at the exact moment the code triggered.
03
Inspect the named subsystem with our app's AI explanation — get vehicle-specific causes for your make, model and year.

Decode P0303 on your actual car

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