What is OBD-II and does my car support it?

OBD-II (On-Board Diagnostics II) is a standardized system in all cars manufactured after 1996 in the US and 2001 in the EU. If your car was built after these dates, it almost certainly has an OBD-II port, typically located under the dashboard near the steering column.

How does GaugeAI diagnose car problems?

GaugeAI uses advanced AI models trained on millions of diagnostic records to analyze your OBD-II error codes, sensor data, and vehicle information. It cross-references manufacturer-specific databases to provide accurate, plain-English explanations and repair recommendations.

What OBD-II scanners are compatible with GaugeAI?

GaugeAI works with any ELM327-based Bluetooth or WiFi OBD-II scanner. Popular options include BAFX Products, Veepeak, and BlueDriver. You can also upload data manually through photos, CSV files, or raw diagnostic logs.

Is GaugeAI accurate enough to replace a mechanic?

GaugeAI achieves 99.2% accuracy in code interpretation and provides detailed repair guidance. While it is an excellent first-line diagnostic tool that can save unnecessary mechanic visits, we recommend professional inspection for complex repairs and safety-critical issues.

Which car brands and models does GaugeAI support?

GaugeAI supports over 10,000 vehicle models across all major manufacturers including Toyota, Honda, BMW, Mercedes-Benz, Ford, Chevrolet, Hyundai, Kia, Volkswagen, Nissan, Changan, and many more. Our AI is trained on manufacturer-specific diagnostic data for more precise results.

How much does GaugeAI cost?

GaugeAI offers a free plan with 5 diagnostic scans per month. Our Pro plan at $14/month includes unlimited scans, full diagnostic history, repair cost estimates, and priority AI analysis. Fleet plans start at $89/month for businesses managing multiple vehicles.

Is my vehicle data secure and private?

Absolutely. All diagnostic data is encrypted in transit and at rest using AES-256 encryption. We never share your vehicle data with third parties. You can delete your data at any time from your account settings. We are SOC 2 Type II compliant.

Can I use GaugeAI without an OBD-II scanner?

Yes. While direct OBD-II connection gives the most comprehensive results, you can also upload photos of your dashboard warning lights, paste error codes manually, upload CSV data exports from other tools, or share scanner screenshots for AI analysis.

High SeverityDo Not Drive

What does P0303 mean?

Cylinder 3 Misfire Detected

Direct Answer

P0303 indicates a misfire in cylinder 3. Use the coil-swap method to quickly determine whether the cause is the ignition coil, and then check the spark plug, injector, and compression.

Common Symptoms

✓Check engine light on
✓Rough idle
✓Engine shaking
✓Sluggish acceleration

Common Causes

01Worn spark plug
02Failed ignition coil
03Faulty injector
04Low compression in cylinder 3

How to Fix P0303

Swap coil from cylinder 3 to another

If the misfire code changes cylinder, the coil is faulty. Replace it.

Replace spark plug in cylinder 3

Inspect for wear, fouling, or damage.

Test injector

Check for pulse and spray.

Frequently Asked Questions

Can P0303 be caused by an oil leak into the cylinder?

Yes. A leaking valve cover gasket can allow oil into the spark plug well, fouling the plug and causing a misfire. Inspect the plug wells for oil contamination before buying new parts.

Estimated Repair Cost

$30–$1500

Same as other single-cylinder misfire codes.

Safe to Drive?

No — avoid driving

Do not drive with a flashing check engine light.

Related Codes

P0300 P0301 P0302 P0304

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