Work from the symptom rather than a guess. Pick what your car is actually doing and get the common causes ranked by how often they turn out to be the fault, with realistic UK costs.
Start with the symptom, not the guess
Most expensive repairs start with somebody replacing a part because a forum said so. Working from the symptom instead — the exact noise, when it happens, what makes it worse — narrows the fault far faster and far cheaper.
Pick the symptom that matches your car below and you will get the common causes ranked by how often they actually turn out to be the problem in a workshop, with realistic UK costs against each one.
The four questions that diagnose most faults
When does it happen — cold start, hot, only when braking, only over bumps, only above a certain speed? A fault that only shows cold points somewhere very different from one that only appears when everything is up to temperature.
Does it change with road speed or engine speed? Noises that rise with road speed are wheels, tyres, bearings and driveshafts. Noises that rise with engine speed are belts, pulleys, the exhaust and the engine itself.
Is there a warning light? A stored fault code turns a guessing game into a starting point. Use the free fault code lookup and read the code before you spend anything.
Has anything been done to the car recently? A fault that starts the week after a service is very often connected to that service.
What is safe to drive with and what is not
Stop driving immediately for a red warning light, a brake pedal that goes soft or long, steering that has gone heavy or vague, a burning smell, or steam from under the bonnet. These are all things that get dramatically worse and more expensive within a few miles.
You can usually drive carefully to a garage with a steady amber engine light, a squealing brake wear indicator, or a knock over bumps — but book it in rather than living with it. A flashing engine management light is the exception: that means unburnt fuel is going into the catalytic converter and you should pull over.
Getting a straight answer on your own car
The guides here cover the common causes, but every car is different. If you want the fault looked at properly against your registration, mileage and exactly what you are hearing, Bob will write you a personal reply for £14.99 — a real qualified mechanic with 32 years on the tools, not a chatbot, back within six hours.
Frequently asked questions
How do I find out what is wrong with my car?
Start with the symptom and when it happens, then read any stored fault codes. That combination narrows almost every fault to two or three likely causes before a spanner is picked up.
Is a knocking noise over bumps serious?
It is usually a worn anti-roll bar link, drop link bush or top mount — cheap parts. It can also be a failing suspension arm or ball joint, which is a safety item, so get it looked at rather than ignored.
Should I read the fault code before going to a garage?
Yes. Knowing the code means you can sanity-check the diagnosis and the quote, and it stops a small fault becoming a fishing expedition.
Can I get advice on my specific car?
Yes — a written answer from a qualified UK mechanic on your own vehicle is £14.99, with a reply back within six hours.