Most independent garages in the UK charge £40 to £75 for a diagnostic check in 2026. Main dealers often charge £80 to £150. But "plug it in and read the codes" is only the start of finding a fault. The garages that make money on diagnosis charge for the time it really takes, explain that clearly up front, and never do it for free. Here's how to set your price and stop customers arguing about it.
What other garages charge
| Type of check | Typical independent price | What it usually covers |
|---|---|---|
| Basic code read | £30 – £50 | Plug in, read and explain the fault codes |
| Diagnostic check (most common) | £40 – £75 | Up to an hour: codes, live data, basic tests, a clear answer or next step |
| Further diagnosis | Your hourly rate | Agreed with the customer in steps, for faults that take longer |
| Specialist (EV, ADAS, prestige) | £80 – £150+ | Needs extra kit, software and training |
Why you should never diagnose for free
"Can you just plug it in?" sounds like a two-minute job. It rarely is. The tool, the software subscription and the training behind it cost real money, often several thousand pounds a year. And a fault code isn't an answer. A code for a misfire can mean a plug, a coil, an injector, a wiring fault or a mechanical problem.
Charging for diagnosis isn't greedy. It's charging for skilled work, the same as any other job.
Three ways to price diagnosis
1. A fixed price for the first hour
The most common approach, and the easiest for customers to say yes to. "Our diagnostic check is £60. That covers up to an hour finding the fault. If it needs longer, we'll call you first with what we've found and a price." The customer knows the most they'll pay before they hand over the keys.
2. Charge it, then take it off the repair
Some garages take the diagnostic fee off the bill if the customer goes ahead with the repair. It helps win the job and stops the customer taking your answer elsewhere. The catch: you're doing the diagnosis for free on every car you repair. Only do this if your labour rate allows for it.
3. Hourly, agreed in steps
For intermittent and electrical faults, agree a set amount of time, report back, then agree the next step. "We've spent an hour. We've ruled out the sensor and the wiring to it. Next we'd check the ECU connections, about another hour." The customer stays in control, and you're paid for every hour.
How to explain the charge so customers say yes
Most arguments about diagnostic charges come from surprise, not the price. Say it before you start, in plain words:
- Say what they get, not just the price. "For £60 you get up to an hour of a qualified technician finding the fault, and a written report with photos and a price to fix it."
- Explain why codes aren't enough. "The code tells us where to look. It doesn't tell us which part has failed. That's what the testing is for."
- Put it on the estimate. A written estimate the customer has agreed to, sent before you start, ends most disputes before they happen.
- Call before going over. Never run past the agreed time without the customer's OK. Record that they said yes and when.
When the customer won't pay for the repair
Some customers pay for the diagnosis and take the car elsewhere. That's fine: you've been paid for your time. Give them a clear report of what you found. It's professional, and it often brings them back when the cheaper garage gets it wrong.
If a customer refuses to pay for diagnosis they agreed to, you may be able to hold the car until the bill is paid. That's called a lien, and it's why the written agreement matters. Our guide on handling customer complaints covers disputes over bills.
Is diagnosis worth investing in?
Yes, for most garages. Cars are full of electronics, and EVs, hybrids and driver-assist systems are adding more. Good diagnosis brings in the jobs other garages turn away, and customers who've had their fault found tend to stay loyal. Price it as the skilled work it is, at your normal labour rate or above. If you're not sure what that rate should be, use the labour rate calculator. For the newer systems, see our guides to ADAS calibration and hybrid servicing.
In Autex, technicians add photos and notes to the job as they diagnose, and you send the customer an estimate they can approve from their phone before you carry on. Book a demo to see it.