Identify the car
Use a registration or enter the make, model, year and engine details available to you.
Free online car symptom review
Free AI mechanic for car noises, warning lights and fault codes.
Use Signal to organise a car noise, dashboard warning or OBD code into a clearer report. Add the vehicle details and describe when the symptom happens; you can also include a short audio or video recording. Signal considers the supplied clues together and suggests possibilities and next checks. It cannot confirm a fault or tell you whether a vehicle is safe to drive. Start without an account; sign in only if you want to save the result to your garage.
Start a symptom reviewHow the review works
Vehicle context matters
The same noise or warning can mean different things on different vehicles and in different conditions. Signal keeps the context alongside the symptom.
Describe the change
Say when the symptom happens, how long it lasts, and what makes it change.
Add optional evidence
Where available, include a short recording, dashboard information, or an OBD code copied exactly as shown.
Review the report
Use the reported observations and suggested next checks to explain the issue to a garage or guide further investigation.
Questions drivers ask
Describe what you noticed in your own words
You do not need to know the name of a failed part. Start with the sound, warning or change you observed, then add when it happens and the vehicle details you know.
“What does a ticking noise at idle mean on my car?”
Include whether it happens from a cold start, continues when warm, changes during normal use, or appears with a warning. Read the engine-ticking guide →
“Why does my car grind when I brake?”
Describe any change in pedal feel, braking, warning lights or stopping distance. If braking feels different or you are unsure the car is safe, stop somewhere safe and seek qualified help. Read the brake-noise guide →
“What does this warning light or OBD code mean?”
Give the exact warning text or code, plus make, model and year if known. A code is a clue for further checks, not proof that a particular part has failed.
“Why does my car click when turning?”
Note whether the car was moving, whether the sound repeated, and any steering, braking or handling change. Read the clicking-when-turning guide →
“Why does the noise only happen over bumps?”
Note when it occurs, whether it changes while turning, and any vibration or handling change. Do not try to reproduce a symptom if that could put anyone at risk. Read the knocking-over-bumps guide →
“Why is my car humming while I drive?”
Note the approximate speed and road surface if you already know them, plus any vibration or handling change. Do not swerve or change gear to test the sound. Read the humming-noise guide →
Common questions
Questions about an AI mechanic
Understand what an online symptom review can help with, what evidence matters and when a physical inspection is needed.
Is Signal’s AI mechanic free?
Yes. Signal’s online diagnostic review is free to use, subject to service availability and capacity. Add vehicle details and a symptom, then review possible explanations and suggested checks. It does not confirm a fault or guarantee that a service response will be available.
Do I need an account to try the AI mechanic?
No. You can start an online review while signed out, subject to service availability and capacity. Sign in only if you want to save the result to your Signal garage.
Can an AI mechanic diagnose my car?
An AI review can organise symptoms and suggest possible explanations or next checks. It cannot confirm which component has failed or whether a car is safe to drive; a qualified inspection may be needed.
Can AI tell what a car sound means?
A recording can add useful evidence when it is available, but similar sounds can have different causes. Signal’s sampled video frames are still images, not continuous motion analysis, and a sound match is not a confirmed fault.
What should I include in a car symptom checker?
Give the make, model, year and engine if known. Describe when the sound, warning or vibration occurs, what changes it, and any exact warning text or OBD code. Separate what you observed from what you think caused it.
When should I stop driving and get help?
Stop somewhere safe and seek qualified assistance for a serious brake or steering change, overheating, smoke, a strong fuel smell, loss of control or any warning that makes the car feel unsafe.
Start with what you noticed
Read the car noise guide →Car noise, warning light, or vibration?
Use the guide to describe the symptom clearly, then open a Signal review if you want to organise the evidence.