The five-minute check before you order
Did the number come from this car, or from a car like it?
A number from last week’s identical-looking job, from a forum, or from a supplier catalogue is a hypothesis. A number resolved from this car’s VIN is an answer.
The distinction matters most when the two agree, because that is when nobody checks.
Is this the end of the chain?
Numbers get superseded quietly. A number that was correct on an invoice from two years ago may sit two links back now, and stock still exists against old links.
The catalog walks the chain in a second. Ordering from the last link is the whole point of looking.
What else does the diagram show fitted?
Clips, seals, bolts and gaskets are shown on the exploded diagram with quantities, and they are the parts that turn a one-visit job into a two-visit job when they arrive missing.
Reading the diagram before ordering costs less than the second delivery. See how to read an exploded parts diagram.
Does anything on the car contradict the record?
Look at what is actually fitted before ordering the replacement. If the car carries something other than what the catalog specifies, work out why now rather than after the parcel arrives.
Our post on when the catalog and the car disagree covers the usual reasons.
Frequently asked questions
Is a VIN check needed on an obvious job?
Obvious jobs are where wrong parts concentrate, because nobody checks when the answer feels certain.
How long does the check take?
Under five minutes for all four questions once the habit is formed, against a second delivery and an idle bay when it is skipped.
What gets forgotten most often?
The small hardware. Clips, seals and single-use bolts appear on the diagram with quantities and are the usual reason a job needs a second visit.