DIAGNOSTIC FEE CALCULATOR

What the fee actually buys

one to one and a half hours of labor of technician time, on a lift, with a scan tool, a meter and a service database subscription behind it. The published band is $80–$250 per diagnostic test, and usually more at a dealership — which is the rate gap applied to the same hour.

Price it as time and it is defensible. Price it as a flat number pulled from the air and it is the first thing a customer challenges.

The second hour

Base diagnosis is a scan, freeze-frame data, a visual and a road test. Beyond that — smoke-testing an intake, pressure-testing a fuel system, back-probing a harness, pulling an intake to reach a sensor — is more time and it needs a second authorisation. The extra hours field is there so you quote it rather than absorb it.

Crediting it to the repair

Many shops apply the diagnostic fee to the repair if the customer approves the work. It is a good policy and a bad habit at the same time. Good, because it removes the objection. Bad, if you never track how much diagnostic time you gave away on jobs that were approved anyway — that shows up later as a sagging effective labor rate. Several states require the diagnostic fee to be disclosed on the estimate before work starts; see written estimate laws by state.

Toggle the credit off in the sheet and you can see the two totals side by side. If the gap is large across a month, the answer is not to drop the policy; it is to price the diagnosis at the hours it really takes.

Where the hours go

Two codes account for a large share of diagnostic tickets, and neither is a part-replacement job: P0420 catalyst efficiency, where the converter is the expensive wrong answer more often than it is the right one, and a random misfire, where the cause list is long and the test order matters.