P0303 typically costs between about $150 and $600 to fix, depending on the root cause and labor rates. The most common fixes—such as spark plug and ignition coil replacements—are usually toward the lower end, while injector issues or mechanical problems can push the bill higher.
What P0303 means
P0303 is the diagnostic trouble code that signals a misfire in cylinder 3. When the engine’s computer detects that cylinder 3 isn’t firing properly, it stores P0303 and may illuminate the check engine light. Causes can range from a faulty spark plug or ignition coil to a dirty fuel injector, vacuum leak, or, in rarer cases, a mechanical issue like low compression.
Common causes and typical costs
The following are the most common causes of cylinder 3 misfire and the typical cost range to fix each issue in a typical passenger vehicle. Costs vary by vehicle, part prices, and local labor rates.
- Spark plug replacement for cylinder 3 (and possibly coil replacement in the same cylinder): Parts typically $2-$40 for plugs (copper to iridium), coil $40-$180; labor usually 1–2 hours. Total roughly $120-$350.
- Ignition coil failure (coil-on-plug or coil pack dedicated to cylinder 3): Parts $40-$180; labor $60-$120. Total typically $100-$300.
- Fuel injector issue (cleaning or replacement for cylinder 3): Cleaning service $40-$150; replacement injector $120-$350. Total often $100-$420 for a single injector scenario.
- Vacuum leak or intake manifold/hoses causing a lean condition: Repairs $150-$350 for hose fixes or $200-$550 for gasket or more involved leaks; labor dominates.
- Compression or mechanical problems (valve/seal issues, stuck rings, or other engine damage): More extensive repairs commonly range from $1,000 to $4,000 or more, depending on the exact fault and whether major components must be replaced.
- Electrical wiring or sensor-related issues (less common but possible): Wiring repair $50-$200; sensor replacement $100-$250.
Costs vary widely by vehicle make/model, part quality (OEM vs aftermarket), and local labor rates. A misfire can sometimes be resolved with a simple, inexpensive fix, but other times it requires more involved work.
What to expect at the shop
Shops typically diagnose P0303 by confirming the misfire on cylinder 3 and testing the likely components. The steps below outline a typical path and related costs, if applicable.
- Initial diagnostic check and code reading to confirm P0303 and rule out random misfire patterns.
- Inspection of cylinder 3 components (spark plug, ignition coil, fuel injector) and related wiring for signs of wear or failure.
- Repair or replacement of the faulty component (plug, coil, or injector) and any associated hoses or seals if vacuum leaks are found.
- Post-repair test drive and rechecking for codes to ensure the misfire is resolved.
Note: Diagnostic fees may apply, and some shops waive the diagnostic charge if you proceed with the recommended repair.
Cost considerations and tips for getting an estimate
To avoid surprises, consider the following when getting an estimate for P0303 repairs. The list below helps you ask the right questions and compare quotes.
- Ask for an itemized estimate that lists parts, labor, and any diagnostic fees separately.
- Request confirmation of the specific cylinder being affected (cylinder 3 in this case) and which components were tested.
- Clarify whether parts are OEM or aftermarket, and whether the price includes warranty coverage on parts and workmanship.
- Inquire about bundled fixes (e.g., plug + coil) vs. individual parts, and whether you’ll need a compression or leak-down test.
- Shop around and compare a few estimates. Labor rates vary significantly by region and shop type (dealership vs independent shop).
With a clear, itemized estimate, you can compare options and choose a solution that fits your vehicle and budget while addressing the actual root cause.
Summary
P0303 signals a misfire in cylinder 3. Repair costs are highly variable, typically ranging from about $150 to $600, and depend on whether the issue is a spark plug/coil, fuel injector, vacuum leak, or a mechanical engine problem. Start with a proper diagnostic to confirm the cause, then obtain an itemized quote that separates parts, labor, and diagnostic fees. In many cases, a simple plug/coil or injector service fixes the problem, but more extensive mechanical issues can substantially increase the cost.