Frequently Asked Questions
Everything about how Fix My Car Sound works, how to get the best results, and what to do after your diagnosis.
You record up to 15 seconds of your car sound using your phone's microphone. Our AI converts the audio into a dual-panel spectrogram — a visual map of frequency and intensity over time — and compares it against a library of confirmed fault recordings. Any context you provide (when the sound occurs, driving conditions) is used to eliminate physically impossible diagnoses before visual analysis begins. Results are delivered in about 60 seconds.
Yes — completely free. Record your car sound and get an AI-powered diagnosis at no cost. No account, no subscription, no credit card required.
Fix My Car Sound covers 19 diagnostic categories including rod knock, engine misfire, brake wear indicator, wheel bearing noise, power steering pump whine, timing chain rattle, exhaust leak, suspension clunk, differential gear whine, valve train and lifter noise, torque converter shudder, heat shield rattle, metal-on-metal grinding, bad starter, turbo whine, transmission pump whine, vacuum leak, accessory belt noise, and normal engine operation.
Overall accuracy is 76% top-1 and 88% top-3 across all 19 categories. For high-confidence classes like rod knock, brake wear, wheel bearings, engine misfire, and timing chain rattle, accuracy is near 100%. Some acoustically ambiguous conditions — vacuum leaks, accessory belt noise, transmission pump whine — hit a physics-based ceiling and are best supplemented with OBD-II data. Every diagnosis includes a confidence score.
Top-3 accuracy means the correct diagnosis appears somewhere in the AI's three most likely predictions. At 88% top-3, the AI correctly identifies the fault in one of its top three guesses 88% of the time. This matters because many car sounds have overlapping characteristics — the AI's second or third guess is often clinically relevant even when it is not the primary diagnosis.
Hold your phone within 12–18 inches of the suspected noise source. Record during the exact conditions when the sound occurs — if it only happens under acceleration, record while accelerating. Turn off the radio, close windows, and avoid recording in high-wind conditions. The AI analyzes the full 15 seconds, so capturing the complete sound cycle produces the most reliable result.
The confidence score (0–100%) reflects how closely your recording matched the AI's training data for the identified fault. Above 80% indicates a strong acoustic match. Between 50–80%, the AI identified a probable fault but the recording may have been noisy or the sound mild. Below 50%, treat the result as a starting point for investigation rather than a definitive answer.
For red-severity results (rod knock, brake wear, wheel bearing, metal-on-metal grind), stop driving and arrange a tow or immediate inspection. For yellow-severity results, schedule a shop appointment within a few days. For green results or low-confidence diagnoses, use the result as context when describing the problem to a mechanic — the AI's top-3 predictions are a useful starting checklist for a technician.
The most common reasons: the recording did not capture the sound clearly, the fault is in an acoustically ambiguous category, or the sound has more than one contributing cause. Try recording again closer to the source and during the exact conditions when the sound is loudest. The top-3 predictions often provide useful context even when the primary result seems off.
No — Fix My Car Sound is a diagnostic aid, not a replacement for professional inspection. It is best used to arrive at a mechanic with a specific hypothesis rather than no information at all. For any safety-critical finding (brakes, bearings, engine knock), always confirm with a qualified technician before making repair decisions.
Fix My Car Sound is optimized for internal combustion engine vehicles and hybrids. Brake wear indicator and wheel bearing noise apply equally to EVs. Most other categories — engine misfire, timing chain, exhaust leak, valve train — are specific to ICE components and are not applicable to battery-electric vehicles.
Your recording is uploaded securely over HTTPS, processed to generate a spectrogram for AI analysis, and stored in encrypted AWS S3 storage. Audio files are automatically deleted after 90 days. We never sell or share your audio with advertisers or third parties. You can request immediate deletion by contacting support@fixmycarsound.com.
A spectrogram is a visual map of audio — frequency on the vertical axis, time on the horizontal axis, and intensity shown by color brightness. The AI uses a dual-panel spectrogram: the top panel covers 20–11,025 Hz to capture the full sound range; the bottom panel zooms into 0–3 kHz with independent scaling to resolve subtle low-frequency patterns. Rod knock appears as periodic vertical lines at crankshaft frequency; wheel bearing failure shows a continuous amplitude-modulated hum. These frequency signatures are what the AI has learned to recognize from confirmed fault recordings.
A skilled mechanic in person can also observe visual symptoms, check fluid levels, and perform physical tests that audio analysis cannot replicate. The AI's advantage is consistency — it applies the same analytical framework to every recording without fatigue or variance between technicians. It also works from audio captured during the actual fault condition, rather than requiring the fault to be reproducible in a shop setting.
The most impactful fields are when the sound occurs (idle, acceleration, braking, turning) and whether it is speed-dependent or RPM-dependent. These are used as hard gates to eliminate impossible diagnoses — a sound only present under braking cannot be rod knock, which is RPM-linked. Answering these fields accurately has a larger impact on result quality than microphone placement.
Yes. Every diagnosis generates a unique shareable link you can send to a mechanic, post in a forum, or forward to a family member. The shared page shows the full diagnosis text, severity, confidence score, and top-3 predictions. No account is required to view a shared result.
Yes. After a diagnosis is completed, a Download PDF button is available. The PDF includes the severity verdict, full diagnosis text, estimated repair cost, top-3 predictions, and a timestamp — useful for sharing with a mechanic or keeping a maintenance record.
Yes. We prioritize new categories based on user feedback. If you have a sound we do not cover or think a category needs improvement, let us know via the contact form. We read every message.
Email us at support@fixmycarsound.com or use the contact form. We aim to respond within 24 hours on business days.