Answer each question with whichever option matches your car best. There are no wrong answers - if two options both apply, pick the one that stands out most.
How the Symptom Finder Works
Most drivers do not have a fault code - they have a car that will not start on a cold morning, a wobble at 60 mph, or a light that has just appeared on the dash. This tool works the same way a mechanic's brain does at the counter: it starts from what the car is doing, asks the handful of questions that split the possibilities apart, and ends with a shortlist ranked by what we genuinely find most often. Every result links to the relevant free guide or fault code page on this site, so you can go from symptom to fix in a couple of clicks.
The Traffic Light System
Every result comes with one of three verdicts. They answer the question people actually ask us: can I keep driving it?
The Symptoms We See Most in the Workshop
Cars that will not start top the list every winter. On diesels the story is nearly always the same: hard starting on cold mornings that gets worse week by week means glow plugs, and testing them takes ten minutes with a multimeter. On petrols, a car that cranks strongly but never fires usually is not getting fuel or spark - and a fuel pump that has stopped priming is the more common of the two.
Warning lights cause the most panic and are often the least urgent. A steady engine management light with the car driving normally is rarely an emergency - read the code before spending anything. The exceptions are the red oil pressure and coolant temperature lights: both mean stop now, because a few minutes of driving can turn a £20 fault into a £2,000 engine.
Noises are where a few honest questions do the most good. Grinding when braking means the pads are into the metal - that is brakes-off-today territory, not next month. A knock over speed bumps is usually a £20 drop link rather than anything sinister. A hum that rises with road speed and changes when you swerve gently is a wheel bearing, and it will not fix itself.
Smoke colour is one of the oldest diagnostic shortcuts in the trade and it still works: white and sweet-smelling points at coolant, blue means burning oil, black means over-fuelling. The tool walks through each one, including the harmless cases - steam on a cold morning and the single black puff a diesel makes during a DPF regeneration are both normal.
This tool gives you the same shortlist I would give you over the counter, but no website can road test your car. Use it to understand the problem and avoid being blinded with science, not as a substitute for putting hands on the car - especially for anything involving brakes, steering or suspension. If in doubt, have it inspected before driving further.
