Diagnostics
Finding the cause, not the code
Reading a fault code takes ninety seconds and almost anyone can do it. Working out what caused the code is the part that saves you money.
The process
How a diagnosis actually goes
These steps are numbered because the order matters — each one narrows what the next has to search.
- 01
Listen to the car and to you
When it happens, how often, what changed. An intermittent fault that only appears cold is a different search from one that appears under load.
- 02
Read what the vehicle has stored
Fault codes, freeze-frame data and live values. A code is a starting point — it names a circuit or a reading that fell outside range, not the part that failed.
- 03
Test the circuit, not the guess
Measure the sensor, the wiring, the connector and the supply before condemning anything. Most "bad sensors" are a bad connection reporting honestly.
- 04
Reproduce the fault
A repair that cannot be verified is a repair that has not been proven. Where the fault can be recreated, it gets recreated.
- 05
Explain what we found
What is wrong, what it will take, and what can wait. You decide what happens next.
Common symptoms
What people usually arrive with
General guidance, not a diagnosis of your specific vehicle — every car needs testing before anyone can say what is actually wrong with it.
Select what your car is doing
Check-engine light is on
The engine computer stored a fault because a reading fell outside its expected range. The code names the circuit or the reading — not the part that failed.
Commonly indicates
- An unmetered air leak after the mass-airflow sensor
- A failing oxygen or air-fuel-ratio sensor
- Ignition coil or spark plug wear on one cylinder
- A loose or failed fuel-filler cap seal
- An evaporative-emissions leak somewhere in the system
What we would check
- 01Read stored codes and the freeze-frame data captured when the fault set
- 02Compare live fuel-trim values at idle and under load
- 03Check for intake leaks before replacing any sensor
- 04Test the named circuit end to end — supply, ground, signal, connector
A steady light usually means it is safe to drive to us. A flashing light means stop driving — it can damage the catalytic converter.
This is what we’d diagnose — not guess at.
Request serviceStraight answers
What we will and won’t tell you
We will tell you what we found, how we found it, and what it will take to fix. If something can safely wait, we will say so rather than bundling it in.
We will not quote a repair before the fault is understood. A number given before the testing is a guess wearing a price tag, and it is usually wrong in the direction that does not favour you.
If the fault turns out to need something we are not set up for, we will tell you that too.