What should a UK garage charge for diagnostics in 2026?

There is a strange gap in UK garage pricing. For the same diagnostic work, on the same car, consumer comparison sites put independent workshops at roughly £40 to £80 and main dealers at £90 to £150. Same fault, same equipment category, same skill, and in many cases the independent has the better technician.

Those figures are retail prices scraped from consumer-facing sites, not an official statistic, and I would treat them as a rough guide to the market rather than gospel. But the shape of the gap is real and it is not explained by cost. It is explained by permission. Main dealers charge what diagnosis is worth because nobody argues with a main dealer. Independents charge what they think they can get away with.

Diagnosis is the most expensive work in the building to provide

Consider what an hour of it actually consumes.

The technician. Diagnosis needs your best person, not your quickest. That is the highest wage in the workshop and the one you can least afford to have standing still.

The equipment. A multi-brand diagnostic platform is a serious purchase, and the annual subscription that keeps it reading current vehicles runs into four figures on its own. Add manufacturer-specific access where you need it, oscilloscopes, a decent battery support unit, and the wiring diagram subscription nobody counts. I am not going to quote a single number for this because it varies enormously by what you cover, but every workshop owner reading this already knows their own annual figure and knows it is not small.

The unbillable half. The reading is quick. The interpreting is not. Checking a live data stream against what it should be, finding the wiring diagram, ruling out the three easy causes before the awkward one, is real time that a customer often imagines was a machine doing the work.

Set against that, £45 is not a price. It is an apology.

Why the flat fee is the wrong shape

The flat diagnostic fee is popular because it is easy to advertise, and it is the source of most of the money lost on diagnosis.

A fault code read on a car that stored one obvious code takes ten minutes. An intermittent electrical fault that appears when the car is warm and stops when you look at it can take three hours across two days. Charge one fee for both, and you have not built an average. You have built a system where the easy jobs earn a little and the hard jobs, the ones that needed the expensive equipment and the best technician, are done at a loss.

It is also the pricing that most reliably ends in an argument, because the customer bought "a diagnostic" and believes they bought an answer. When the honest outcome after ninety minutes is "it is not the sensor, and I now need to test the loom", a flat fee gives you no language for that conversation.

The alternative is to sell time, in defined blocks, with a checkpoint:

• The first hour is charged at or near your labour rate, and it buys an hour of investigation, not a guaranteed answer.
• If the fault is found inside the hour, you quote the repair. Most jobs end here.
• If it is not, you go back to the customer with what has been ruled out, and quote the next block.

The customer keeps control of the spend, you stop absorbing open-ended time, and the difficult car stops being the one you dread booking in.

The free-diagnostic trap

"Free diagnostics if we do the work" sounds like a sales offer and behaves like a discount on your most skilled labour.

Crediting the fee against the repair is a different and defensible thing: the diagnosis was genuinely part of that job, and the customer is paying for the whole of it. Advertising it as free is not. It carries the cost of every car that turns out to need nothing, every customer who takes your answer to a cheaper garage, and every fault that is found but the work declined. You did the hard part in all three cases and were paid for none of them.

If you want the offer, cap it. Credit the fee against work over a stated value, and say so in writing on the job card. What you cannot do is price the skilled part at zero and hope the volume covers it, because the volume is made of exactly the jobs where it does not.

What to charge

Working from the market ranges above and from what the work costs to provide, for an independent workshop in 2026:

• Below £50 for an hour of diagnosis is under cost in most of the country once you count the technician and the subscriptions. If you are there, you are subsidising it from servicing.
• £60 to £90 for a first hour is a defensible independent price in most regions, and it should sit at or near your standard labour rate rather than below it. Check yours against the regional bands in our hourly rate guide.
• Above £90 is normal for specialist diagnostic work, ADAS, and anything requiring manufacturer-level access. Main dealers are at £90 to £150 for work an experienced independent often does better.

The most common mistake is not the number. It is charging a diagnostic fee that is lower than your own labour rate, which says, in public, that the most technical hour you sell is worth less than the routine ones.

Make the time visible before you reprice

Before changing a price, find out what diagnosis is actually costing you. Book it as its own job with its own clocked time for a month, rather than folding it into the repair or leaving it off the card entirely. Most workshops discover two things: that diagnosis takes longer than the fee assumes, and that a meaningful amount of it was never recorded on a job card at all.

That measurement matters more than the price you pick. A fee you set by feel will drift back down under pressure from the next customer who queries it. A fee you can defend with your own recorded times will not, because you will know exactly what you are giving away when you drop it.