Kam Autos · Derby
How We Diagnose Car Faults
Diagnosis at Kam Autos follows a fixed sequence: fault codes are read, live data is compared with expected values, the car is road-tested where needed, and the cause is explained with a written quote before any repair starts. No part is changed on a code alone.
Step 1: fault codes
Diagnostic equipment reads the car's OBD-II trouble codes, which say which system reported a problem. A code is a starting point, not an answer: one code can come from a sensor, its wiring, or the mechanical part it watches.
Step 2: live data and sensors
Live data shows what the sensors are actually reporting while the car runs. Coolant temperature, lambda, crankshaft and MAF sensors are compared with expected values, and the ECU's readings are checked against the physical condition of the parts.
- OBD-II trouble codes read from the car's systems
- Live sensor data compared with expected values
- Coolant temperature, lambda, crankshaft and MAF sensors checked
- Wiring and connectors inspected in the suspect circuit
Step 3: road test
Where the fault only appears while driving, the car is road-tested to reproduce it. A fault that cannot be reproduced cannot be proven, and an unproven fault is not repaired on guesswork.
Step 4: explanation and written quote
The cause is explained in plain English: what failed, what it affects, and what the repair involves. The written quote follows, separating urgent work from work that can wait, and repair starts only once the quote is agreed.
Why this order matters
Changing parts on a code alone often replaces a sound part while the real fault remains, which is the misdiagnosis complaint drivers know well. Testing first costs diagnostic time but avoids repeated parts, repeated visits, and a fault that returns a week later.
Frequently asked questions
What is an OBD-II fault code?
An OBD-II fault code is the car's own record that a system reading fell outside its expected range. It identifies the system involved, not the faulty part. Testing the sensors and wiring in that system is what names the part.
Why do you road-test the car?
Some faults only appear under load, at speed, or when warm, so a stationary check cannot reproduce them. A road test reproduces the symptom under real conditions, which is how the cause is proven before a repair is quoted.
Will I get the diagnosis in writing?
Yes. The cause is explained and the repair quoted before work starts, with urgent work separated from work that can wait. That written quote is the record to compare against the finished job and the final bill.
How long does diagnosis take?
Timing depends on the system involved and whether the fault is intermittent. A steady fault is usually quicker to prove than one that appears rarely. An expected timescale is confirmed at booking, never promised in advance.
Book with Kam Autos
Kam Autos, 74-90 Pear Tree Rd, Derby DE23 6QA, United Kingdom. Call +44 7306 311065 or message on WhatsApp — diagnosis before repair, a quote before work, and no hidden charges.