Carautonomy — car parts and warning lights explained
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Cars explained in plain English.

Helping drivers understand how their car works - so they can walk into the garage informed, not intimidated.

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Featured explainer

Horn

The simple electrical warning device you press to alert other road users

Read the full explainer →
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No jargon

Everything is written like a friend explaining it over a cup of tea — no acronyms left undefined.

UK-focused

Rough fitted prices in pounds, MOT-relevant warnings, and advice that matches British roads.

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Carautonomy — car parts and warning lights explained

Helping the UK understand how their cars actually work — one car part at a time.

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A friendly note

Information here is general guidance, not a diagnosis. Always speak to a qualified mechanic before parting with cash.

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HORN — ELECTROMAGNET VIBRATES A METAL DIAPHRAGM⚠driver presses+12 VtriggerRELAYcoilHORNdiaphragmelectromagnetBEEP!Press button → relay closes → coil pulls armature → diaphragm snaps back → vibrates ~400 HzRequired for MOT — must be a continuous tone, loud enough to be heard from outside the car