Diagnose Your Car Online — Free
Tell us what your car is doing — the noise, the smell, the shake, the light — and get a preliminary diagnosis grounded in real repair data for your exact vehicle: likely causes in order, how to confirm each one, and what the fix typically costs. No account, no charge.
Takes about 10 seconds — it reads real spec and repair data for your vehicle, not canned answers.
How the free diagnosis works
- Describe the symptoms in plain language. What you hear, feel, and smell, and when it happens — cold mornings, highway speed, only when turning. Include your year, make, and model, and any check-engine code if you have one.
- Get a data-grounded triage. The diagnosis is built on Open Labor Project's repair database — labor times, torque and fluid specs, diagnostic trouble codes, and NHTSA recalls across 41,000+ vehicles from 1955 to present — not generic canned answers. You get the likely causes ranked, how to confirm each, and typical repair costs so nobody can quote you blind.
- Confirm before you spend. Check the cheap causes first. And when you want professional certainty, a vetted master technician reviews your exact case at The Diag Desk — $25, answered within 24 hours or you pay nothing.
Symptom guides
Deep-dives on the most common complaints — causes ranked by likelihood, how to confirm each, and real repair costs:
Common questions
Is this car diagnosis really free?
Yes. Describe your symptoms and get a preliminary diagnosis at no cost, grounded in Open Labor Project’s database of labor times, torque specs, fluid specs, DTC codes, and NHTSA recalls for 41,000+ vehicles. If you want a vetted human master technician to confirm it, The Diag Desk is $25 with an answer in 24 hours or it’s free.
How accurate is an online car diagnosis?
Treat any online diagnosis — ours included — as smart triage, not a verdict. It narrows the likely causes, tells you what to check first, and what the repair typically costs, so you walk into a shop informed. A hands-on inspection is still how a diagnosis gets confirmed. When the stakes are high, escalate to a real master tech at The Diag Desk.
Can it help with a check engine light or OBD2 code?
Yes — if you already pulled a code (P0420, P0300, etc.), include it in your description and the diagnosis will use our DTC database: what the code means on your specific engine, common causes ranked, and diagnostic steps. Most parts stores will read your code for free if you don’t have a scanner.
Does it work on older and classic cars?
Yes — our database covers vehicles from 1955 to present, including the pre-OBD2 era (1955–1995) that most tools ignore entirely. Describe the symptoms the old-school way — what you hear, smell, and feel — and the diagnosis works from era-correct systems: carburetors, points, mechanical fuel pumps and all.
What happens if the AI diagnosis is wrong?
That’s exactly why we built the escalation path. The Diag Desk connects you to a vetted human master technician — not a bot — who reads your full description, asks follow-ups, and gives a professional diagnosis for $25, guaranteed answered within 24 hours or you pay nothing.
An online diagnosis — from us or anyone — is preliminary triage, not a substitute for a hands-on inspection. For anything safety-critical (brakes, steering, fuel leaks), have the vehicle inspected before driving it. Related free tools: DTC code lookup, recall check, emergency neutral, and the engine-noise guide.