# P0303 — Cylinder 3 Misfire Detected

> ClearTheCode diagnostic code reference (not OEM service data).

Source: https://clearthecode.com/codes/P0303

**System:** Powertrain · Ignition / Misfire

**Severity:** severe

## Description

Cylinder 3 is misfiring. Inspect spark plug, ignition coil, injector, and compression on this cylinder.

## Diagnostic snapshot

- **Difficulty:** 6/10 — Intermediate diagnostics
- **Est. repair cost:** $120 – $450
- **Common symptoms:** Misfire or hesitation under load, Check engine light (MIL), Rough idle, Reduced power / limp mode

## Diagnostic workflow

1. Confirm P0303 with a live scan — note pending vs stored and freeze frame data.
2. Verify reported symptoms: Misfire or hesitation under load, Check engine light (MIL), Rough idle.
3. Inspect wiring/connectors and related sensors before replacing modules.
4. Most likely fixes: Cylinder-specific misfire diagnosis (swap / compression / injector); Spark plug / coil / ignition diagnosis.
5. Clear codes and road-test; re-scan after two drive cycles if the monitor must set.

## Likely fixes

1. **Cylinder-specific misfire diagnosis (swap / compression / injector)** (moderate)
2. **Spark plug / coil / ignition diagnosis** (moderate)