Warning lights traced to a cause, not just read and cleared

Why a fault code is not a diagnosis

This is where more money gets wasted than anywhere else in motoring. A car throws a code for a lean mixture on bank one. The cheap route is to fit an oxygen sensor, because that is what the code mentions. Half the time the sensor was reading perfectly correctly and reporting a split intake hose, a leaking manifold gasket or a failing fuel pump — and the customer has bought a sensor they did not need and still has the fault.

What happens here instead: the code is read, then the live data is looked at while the engine runs, then the actual circuit or system is tested. It takes longer. It is the reason the fault is fixed once.

Common things people bring in

• Engine management light. On steady, or flashing — and flashing means stop driving, because it usually indicates a misfire dumping raw fuel into a very expensive catalytic converter.
• ABS, traction control and airbag lights. All three are MOT failures. Wheel speed sensors, rings, clock springs and connectors under seats are the usual suspects.
• Intermittent electrical faults. The hardest kind and the most frustrating to live with. Corroded earths, chafed looms, water in connectors.
• A car that will not start, or starts and dies. Battery, alternator, starter, immobiliser, fuel delivery or crank sensor — tested rather than replaced in sequence until it works.
• Overheating, or a heater that blows cold. Thermostats, water pumps, air locks, matrix blockages, and head gaskets confirmed properly before anyone says the word.
• Noises. Knocks over bumps, whines that change with speed, grinding on turns, clicks on full lock. Most are diagnosable from a drive and a look, without any equipment at all.

Brakes

Pads, discs, calipers, flexi hoses, corroded brake pipes, handbrake cables and electronic parking brakes. Pad thickness is measured and written down in millimetres rather than described as "getting low", so you know whether you have six months or six weeks.

Quality-brand friction material as standard. Brakes are not the place to save £20 — cheap pads glaze, fade when hot, and eat discs.

Suspension and steering

Shock absorbers, springs, top mounts, wishbones, bushes, anti-roll bar links, track rod ends, ball joints and wheel bearings. Uneven tyre wear is usually the first sign, and it is worth chasing — a worn bush ruins a set of tyres far faster than it ruins the ride. Alignment is checked after any suspension work.

Everything else

Batteries and charging systems, alternators and starters, exhausts and emissions, air conditioning faults, wipers, lighting, cooling systems, cambelt-adjacent auxiliary belt and pulley work, and the general list of jobs that make up most weeks in any real workshop.

Before an MOT

A pre-MOT inspection catches the things that fail tests — brakes, tyres, suspension, lights, wipers, corroded pipes, and warning lights that are on. Anything found is quoted before the test, and Erdi takes the vehicle to a local testing station and back as part of the collection service. MB Auto is not itself a testing station.