Diagnostics - what can we do?

Full engine diagnostics & fault-code reading – OBD (on-board diagnostics)

Did you know? Modern cars can log dozens of hidden fault codes even before a warning light shows. Early scans help prevent costly breakdowns.

Check-engine light / warning light investigation – identify and clear faults triggering alerts.

Value add: We identify and clear the root cause of dashboard alerts so the light doesn’t just come back on.

Emission system & M.O.T failure diagnostics – find causes of failed or borderline M.O.T emissions te

Did you know? Emissions faults like a failing catalytic converter or DPF are among the most common M.O.T failures.

Fuel system diagnostics – test injectors and pressure sensors.

Tip: Testing injectors and sensors can improve performance and fuel economy, often paying for itself in fuel savings. .

Ignition & misfire testing – coil packs, spark plugs, timing and related sensors.

Did you know? Misfires waste fuel and can damage the catalytic converter. Prompt diagnosis protects engine components.

ABS, traction control & stability system diagnostics – detect faults in wheel sensors and modules.

Value add: A healthy ABS and traction control system keep you safe in emergency stops and on slippery roads.

Airbag / SRS diagnostics – safely investigate and reset airbag and seat-belt pre-tensioner faults.

Tip: An illuminated airbag light means the system may not deploy in a crash - our diagnostics restore full safety protection.

Battery health checks – test battery condition, alternator output and starter performance.

Did you know? Cold weather can halve a weak battery’s output. Our tests spot low capacity before winter starts.

DPF checks & regeneration – diagnose soot build-up and perform forced regenerations where needed.

Value add: Cleaning or forced regeneration prevents blockages that can lead to costly filter replacement.

EGR valve diagnostics – test and clean exhaust gas recirculation systems.

Tip: A sticking EGR valve can cut fuel economy by up to 20%. Cleaning or replacing it restores efficiency.

AdBlue/SCR system testing – identify faults in selective catalytic reduction systems.

Did you know? Running out of AdBlue can trigger limp mode or even prevent the engine from starting. We test and top up the system.

Cooling system & temperature sensor checks – diagnose overheating, thermostat or fan issues.

Value add: Proper cooling prevents overheating, which is one of the top causes of roadside breakdowns in the UK.

Got a Question About Diagnostics?

Please reach us at craggsrecovery@gmail.com or give us a call 01913385383 if you cannot find an answer to your question.

What is a car diagnostic check?

A diagnostic check connects your car’s computer (OBD system) to professional scanning tools to read fault codes and identify issues with the engine, emissions, safety systems and more.

When should I get a diagnostic check?

Whenever a warning light comes on, your car feels down on power, fuel economy drops, or you notice unusual noises. Many drivers also book a scan before an M.O.T or long journey.

How long does a diagnostic test take?

Most checks take 30–60 minutes, depending on the complexity of the issue. We’ll explain the results and recommended next steps.

How much does a diagnostic check cost?

Prices vary, but a typical garage diagnostic check starts from around £30 at Craggs Automotive Repair & Service. We always confirm costs before starting any repairs.

Will a diagnostic check fix the problem?

The scan itself identifies the cause. We then discuss repair options, from clearing a minor fault code to replacing a part.

Can you clear warning lights?

Yes, but only after resolving the root issue - clearing the code alone will not permanently switch off the light if the fault remains. In some cases, if multiple fault codes appear, we may clear the codes first and then monitor as necessary to identify which code reappears so we know where to focus our attention first.

Can a car pass its M.O.T with a warning light on?

In most cases no. An illuminated engine, ABS, or airbag light is usually an M.O.T fail. A diagnostic check helps prevent this.

What systems can you diagnose?

We cover all major systems including engine, gearbox, brakes, ABS, airbags, emissions, battery.

Can diagnostics find intermittent or hidden faults?

Often yes. Our advanced tools can detect intermittent codes and record live data while the vehicle is running to capture faults that don’t show up constantly.

Should I get a diagnostic check before buying a used car?

Definitely. A pre-purchase diagnostic scan can reveal hidden problems and help you negotiate a better price or avoid costly surprises. But always remember a diagnostic check cannot predict the future.