What’s wrong with my car?
Describe what it’s doing — a noise, a light, a smell, or a trouble code. Redline shows the leading possibilities, what evidence supports them, and what to check next. Free, with no account needed.
Why Redline is different
- 01
Your car, not just the code.
Redline uses the vehicle, the problem, and the evidence together instead of treating a trouble code like the answer.
- 02
Evidence before certainty.
Redline separates what’s supported, what’s still possible, and what needs to be checked next.
- 03
The answer can change.
Save it to My Car, add new results later, and Redline updates the Case instead of starting over.
How it works
- 1Describe the problem
- 2See the leading possibilities and what supports them
- 3Save the Case and keep adding evidence
Common questions
Is it really free?
Yes. Describe the problem and see the leading possibilities without creating an account or entering a card. A free account lets you save it as a Case on My Car and keep adding evidence later.
Do I need an OBD scanner or the trouble code?
No. Plain English is enough — a sound, a smell, a warning light, when it happens. If you already have a trouble code, add it: it narrows the possibilities, but it is never required.
How sure is the answer?
Redline weighs your problem against NHTSA recall and owner-complaint data for your year, make and model, and shows what the evidence supports and what is still missing. When the evidence is thin, it says so. When a problem is safety-critical or beyond a driveway fix, it tells you to see a mechanic.
Will it just tell me to replace expensive parts?
No. It shows what to check before anyone orders parts, so a simple test can rule a possibility in or out before you pay for a repair.
Does it work on my car?
Designed for OBD-II-era US cars and light trucks. Coverage varies by vehicle and available data. The more you add — year, make, model, engine — the more specific the possibilities get.
Looking for something specific? Browse trouble codes, symptoms, or common problems by vehicle.