Vehicle Diagnostics & Repair Guides
Understand your car.
Diagnose it properly.
Real-world diagnostics, repair guides and workshop knowledge to help you understand what is actually going on with your vehicle.
Vehicle lookup
Registration lookup is coming soon
We're building vehicle-specific guides and information into Speed Tweaks. For now, start with a fault code or symptom below.
Start here
What do you need help with?
You shouldn't have to scroll through hundreds of videos hoping to stumble across the answer. Start with the problem you're trying to solve.
I have a fault code
Understand what a diagnostic trouble code actually means and what should be tested before replacing parts.
Search fault codes →
My car has a symptom
No start, warning lights, poor running or strange behaviour? Work through the problem logically and gather useful evidence.
Start guided diagnosis →
I want to learn
Follow real diagnostic cases and learn the methods, tests and reasoning used to find faults properly.
Explore workshop videos →
Diagnostic Help
Start with what you actually know
A fault code is evidence, not a diagnosis. A symptom is a starting point. Choose the route that matches the information you have.
From the workshop
Real diagnostic cases
Real vehicles, real faults and the reasoning behind the diagnosis.
Diagnostic case
Turbo / underboost diagnosis
Follow a real workshop investigation rather than jumping straight to replacing the turbo.
Diagnostic case
DPF pressure fault diagnosis
See how testing and live data help separate a genuine sensor problem from the rest of the system.
Diagnostic case
Fuel-pressure fault diagnosis
A real example of why a fuel-pressure code does not automatically condemn the high-pressure pump.
About Speed Tweaks
Workshop experience without the workshop jargon.
I'm Ray. Speed Tweaks is where I share what I've learned from years of diagnosing and repairing vehicles.
This isn't here to sell you a repair. The aim is to make useful automotive information easier to understand and help people make sense of faults, diagnostics and modern vehicle systems.