#safety
45 posts in Car Diagnostics blog about "safety" — OBD-II diagnostics, DTC codes, repair. ← All posts
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B0001 to B0100: airbag and restraint system codes explained
The one system where a warning lamp means a device may not deploy when you need it. Generic OBD-II usually cannot even see these codes.
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Brake pedal sinks to the floor: stop driving and read this
A pedal that keeps travelling under steady pressure means the hydraulic system is not holding. This is the one fault on the site that justifies a recovery truck.
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Car pulls under braking: caliper, hose or contamination
Pulling only when you brake is a different fault from pulling all the time, and it is a safety issue rather than an annoyance.
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Exhaust smell inside the cabin: treat it as urgent
Exhaust gas contains carbon monoxide, which is colourless, odourless and disabling. Smelling exhaust in the cabin means something is letting it in.
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U0151: lost communication with the restraints control module
The airbag module has stopped answering, which means nothing can confirm the restraint system will work. That makes this a code with a deadline.
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Airbag light on: causes, and why generic scanners often miss it
An illuminated SRS lamp means the airbags are disabled and will not deploy. The cause is usually a connector under a seat, and the code is usually invisible to a basic reader.
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Can OBD scanning damage your car? Separating risk from myth
Reading data is safe. A short list of operations genuinely carries risk, and knowing which is which lets you use a scan tool confidently instead of nervously.
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Grinding when braking: how far past the pads you already are
A squeal is a warning. A grind is the sound of metal on metal, which means the warning stage is over and the bill has already grown.
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P0093: fuel system large leak detected — stop driving and find it
This is one of the few codes that justifies stopping where you are. Diesel at rail pressure onto a hot turbo is a fire, not an inconvenience.
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P0705: transmission range sensor and the car that starts in any gear
The range sensor tells the car which gear you selected. When it fails, the symptoms range from a reverse light that never works to an engine that will start in Drive.
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Power steering warning light: electric and hydraulic causes
Electric and hydraulic systems fail in completely different ways and give completely different warnings. Knowing which one you have decides whether this is a fluid check or a scan.
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Roof bars: fitting, limits, and what changes on a journey
Roof bars change aerodynamics, centre of gravity, and the load the body carries. Fitting, limits, and the real consequences.
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Speed limiters and driver assistance: what they do and what they do not
A limiter and cruise control are different things, and assistance systems have limits the advertising skips. The functions and their boundaries.
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Brake pads: organic, ceramic, or semi-metallic
Different friction materials balance stopping, dust, and noise differently. The types, and why more expensive is not always better.
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Seat belts: buckles, pretensioners, and the lamp you cannot ignore
The belt, not the airbag, is the primary restraint. The faults, the pretensioners, and why an SRS lamp disables the whole system.
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Puncture repair: plug, patch, or mushroom — which is most reliable
Not every puncture is repairable, and not every repair is equally reliable. The methods, the repairable zone, and what cannot be fixed.
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Cruise control: when it helps and when it gets in the way
Cruise saves fuel on level motorways and wastes it in hills. The modes, the adaptive version, and its limits.
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A phone in the car: mounts, charging, and why it overheats
A phone in a car lives in the worst thermal environment there is. Placement, charging, and why a cheap adapter heats and interferes.
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LED bulbs in halogen headlights: why it does not work as promised
An LED in a headlight designed for a filament gives not more light but a wrong beam. Optics, electronics, and the consequences.
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What to tackle yourself and what to leave alone
The line runs not through difficulty but through the consequences of getting it wrong. What is safe to do yourself and where the cost of error dwarfs the saving.
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An emergency kit: what to carry so you do not depend on strangers
A kit in the boot is not for repairing the car but for waiting safely for help. What works and what rides along for nothing.
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Pets in the car: safety, heat, and what changes on a journey
An unrestrained animal is dangerous to itself and to people. Restraint options, the heat risk, and preparing for a long journey.
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Recall campaigns: how to check and why the work is free
A recall is not a brand defect but a problem found and acknowledged. How to check your own car and why it matters most for used ones.
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Child seats and airbags: the mistakes that cost the most
A rear-facing seat in the front with a live airbag is the most dangerous combination in a car. The rules and what the electronics see.
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Dash cams: installing one without a flat battery and stray codes
The most common problem after fitting a dash cam is a flat battery overnight. Power options, mounting position, and the standard mistakes.
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Mountains: how not to burn the brakes descending or cook the engine climbing
A mountain road loads a car unlike a motorway. Engine braking, overheating, and what to check before you go.
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Loading a car: staying within limits and avoiding a missile in the cabin
An overloaded car brakes longer and steers worse. Permitted weights, securing the load, and what changes in the way it drives.
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Dampers: how to tell they are dead without a ramp
A damper wears so gradually that the driver adapts alongside it. The signs, the honest tests, and why this is a braking distance question, not a comfort one.
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Wheel torque: why "as tight as it goes" costs more than a torque wrench
An overtightened wheel costs a rim, a stud, or judder under braking. Why torque matters and what to do after a tyre shop visit.
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Brake fluid: why it is changed by the calendar, not by mileage
Fluid absorbs water even while parked, and that is what makes it dangerous exactly where brakes matter most. Grades, testing, and consequences.
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A spongy brake pedal: what it means and why it cannot wait
A pedal that sinks means air, moisture in the fluid, or a leak. The three scenarios and which of them is the most dangerous.
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The handbrake will not hold: cable and electronic parking brakes
Most people test the parking brake once a year, at the annual inspection. Why cables stretch, how an electronic parking brake differs, and why winter use needs care.
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Breaking down on a motorway: the procedure that protects you, not the car
The most dangerous part of a motorway breakdown is not the breakdown but what driver and passengers do in the first few minutes. The correct order.
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Deep water on the road: what breaks and what to do afterwards
Hydrolock is not the only risk, nor the most common. What depth is critical, why speed is more dangerous than depth, and what to check once it seems fine.
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Headlights: condensation, bulbs that keep blowing, and hazed lenses
Moisture in a headlight is not always a fault, and a bulb never blows for no reason. When condensation is normal, why bulbs fail in pairs, and what diagnostics adds.
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Wipers and washers: the faults you can fix yourself
Two thirds of wiper problems are a fuse, a stripped spline, or a frozen pump. How to separate mechanical from electrical faults in a minute.
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Winter tyres: when to switch and why temperature matters more than snow
The trigger is not the first snow but a steady 7 °C. Why summer rubber hardens, how ageing destroys grip, and what the electronics can and cannot do.
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Dashboard warning lights: what stops the journey and what waits for the workshop
The colour is the priority. Which lights mean stop now, which allow you to drive on carefully, and why a lamp that never illuminates is the worst of all.
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The emergency call system: how it works, when it calls by mistake, and what the button does
The car calls the emergency services itself after a serious impact. How the system decides, why it sometimes calls for nothing, and what the dashboard lamp means.
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The black box in your car: what it records about you at the moment of a crash
The event data recorder captures a few seconds before impact: speed, pedals, seatbelts, steering angle. What is recorded, how long it survives, and who can access it.
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How to jump-start a car properly: the sequence that saves both cars' electronics
On a modern car, jump-starting incorrectly costs more than a new battery. The connection order, why the last clamp does not go where you think, and when you must not jump-start at all.
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The new mandatory safety systems: what appeared in cars and how it behaves
Assistance systems that used to be premium options now come as standard on budget models. What they actually do, why they irritate in the first weeks, and what goes wrong with them after a repair.
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Brake squeal and grinding: which noise is normal and which means "replace today"
Brakes make several different noises, and each one means something specific. Why every car squeaks in the morning, when a squeal becomes a grind, and why electronics is nearly blind here.
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Burning smell in a car: eight sources and how to tell them apart by scent
Burning wiring, a slipping clutch, oil on the manifold, and overheated pads all smell different. Diagnosis by the character of the smell, when it appears, and what diagnostics shows alongside.
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Fuel smell in the cabin: when it is trivial and when you stop immediately
A fuel smell inside the car is the one symptom worth taking seriously straight away. Where it comes from, which variants are harmless, and how OBD narrows the source in ten minutes.