There was a vehicle in the fleet last winter — a curtainsider, six years old, done about 340,000 miles — that had a cracked offside rear spring highlighted on the PMI report from eight weeks before. The fitter had flagged it properly. Green pen, clear handwriting, dated. Nobody had actioned it. It was still on the road.
DVSA pulled it at the Knutsford M6 J18 check site in November. PG9 issued on the spot. Vehicle off the road until repaired at a DVSA-approved workshop. What followed: a traffic examiner visit, a review of the full maintenance records going back 15 months, a written warning from the Traffic Commissioner's office, and a very uncomfortable public conversation about the gap between our PMI process on paper and our PMI process in practice.
The spring repair cost £380. The rest of it cost considerably more.
What the PMI actually is — and what it isn't
The preventive maintenance inspection — PMI — is not the same as the annual HGV test. The annual test is a statutory requirement administered by DVSA, once a year, at an authorised testing facility. The PMI is the regular safety inspection the operator is required to carry out between annual tests, as part of the O-licence maintenance undertaking.
It's also not the same as the pre-drive walkaround check. The walkaround is the driver's responsibility — tyres, lights, fluid levels, bodywork, load security, the thirty-second routine before every journey. The PMI is a structured, workshop-level inspection carried out by a competent person, documented on a safety inspection report, filed, and kept.
The three levels — annual test, PMI, walkaround check — work as a system. The walkaround is daily defence against obvious defects. The PMI is the deeper check that catches deteriorating components before they become dangerous. The annual test is the statutory backstop that catches what both of those missed. When PMIs are being skipped or the paperwork is being faked, the annual test is the only real check left — and by then, something may already have been on the road in a dangerous condition for months.
How often does the inspection need to happen?
DVSA's Guide to Maintaining Roadworthiness recommends inspection intervals no longer than six weeks for most goods vehicles operating under normal conditions. That's not six weeks from when you get around to it — it's a maximum of six weeks from the previous inspection, and the inspection must cover all the required items.
The six-week figure is a guide, not an absolute maximum for every circumstance. Older vehicles, vehicles doing high-mileage or arduous work (tipper work, tanker work, heavy plant recovery), or vehicles operating in poor conditions may need shorter intervals. DVSA expects the operator to assess what their operation demands and set intervals accordingly. Setting six weeks when you're running a fleet of ageing tippers on construction sites and defending that decision in a TC hearing is a conversation nobody wants.
Some operators agree different intervals with DVSA through the Earned Recognition scheme. In standard operations, six weeks is the benchmark. If you're not hitting it consistently, you're vulnerable.
Mileage-based intervals
For vehicles that cover very high mileage — artics doing nightly trunk runs, for example — a six-week interval might be less appropriate than a mileage-based interval. DVSA's guidance acknowledges this. An operator might justify an eight-week interval for a low-mileage local delivery vehicle, or a four-week interval for a tipper doing 1,500 miles a week. The justification needs to be documented, defensible, and consistently applied.
What DVSA wants to see is a maintenance system that's calibrated to the actual operation — not a standard template that was set up when the company started and never reviewed.
What a PMI should cover
The specific items covered in a PMI depend on the vehicle, but the standard list for a goods vehicle includes:
- Brakes — service brake, secondary brake, parking brake efficiency and condition
- Steering — play, condition of joints and linkages
- Tyres — tread depth, condition, correct pressure, wheel fixings
- Lights and electrical — headlights, brake lights, indicators, marker lights, reversing lights
- Suspension — springs, shock absorbers, air bags where fitted
- Undercarriage — chassis, cross-members, fifth wheel or coupling (for artics)
- Bodywork — condition, load security points, doors and latches
- Windscreen and visibility — washers, wipers, mirrors
- Exhaust and fuel system — no leaks, secure mounting
- Tachograph — functional, seal intact, calibration in date
The tachograph calibration point is one that catches operators out regularly. The tachograph must be calibrated every two years by an approved workshop. If the calibration has lapsed, you've got a prohibition risk at the roadside and a recording validity problem stretching back to whenever it expired. A PMI should catch a lapsing calibration before it becomes a roadside problem — I wrote more about the calibration requirement in the tachograph calibration post.
Who can carry out a PMI?
DVSA doesn't require PMIs to be done at an approved workshop. They can be carried out by the operator's own staff — provided that person is competent, has the right equipment, and the inspection is genuinely independent in the sense that the person doing it isn't also the driver of that vehicle.
In practice, most small fleets use an external workshop for PMIs — a franchise dealer or an independent HGV workshop — because it's cleaner from a documentation standpoint and because the liability sits more clearly with a third party if something is missed. For larger fleets with their own workshop staff, in-house PMIs are common, but the competence and independence questions need to be demonstrable.
What matters to DVSA is not who did it but that it was done, it was done properly, and the record proves it.
The documentation — what to keep and for how long
Every PMI must generate a safety inspection report. The report must show: vehicle registration, date of inspection, the identity of the person who carried it out, the items inspected, any defects found, and what action was taken. If defects were found, the record needs to show they were addressed before the vehicle returned to service.
Traffic Commissioners expect to see at least 15 months of maintenance records at a public inquiry. That's the standard benchmark in the industry, and it's the period that covers two annual test cycles with a reasonable margin. Some operators keep records for longer — there's no downside to keeping them for three years, and in a disputed enforcement situation, older records can be useful.
The records should be accessible. Not in a box in the fitter's van. Not in a system that only one person knows how to use. A Traffic Commissioner's maintenance call-up gives you a fixed window to produce documents, and "we can't find them" has the same practical effect as "they don't exist."
What DVSA looks for in a maintenance investigation
A maintenance investigation — sometimes called a maintenance inquiry — is typically triggered by a pattern of roadside prohibitions, a OCRS score that's moved into amber or red, or a specific serious defect that attracted DVSA's attention. The traffic examiner will want to see your maintenance records, your defect reporting system, your driver walkaround records, and how your PMI process connects to your vehicle management.
The questions they ask are predictable: Are inspections happening at the scheduled intervals? Are defects being actioned before the vehicle goes back on the road? Are drivers reporting defects and are those reports being taken seriously? Is the person responsible for maintenance actually competent to make the decisions they're making?
A fleet with consistent, documented PMIs, clear defect records, and evidence that the process is genuinely followed will come through a maintenance investigation with a warning at worst. A fleet where the PMI reports are being created after the fact, or where defects are being marked as actioned without evidence, is in a much worse position — and DVSA has seen every variation of it.
The walkaround check in context
The driver walkaround check doesn't replace the PMI, but it does feed into it. Defects found on walkarounds should be reported in writing, actioned, and confirmed as resolved before the vehicle goes out again. Those records should be available alongside the PMI reports.
A driver who finds a defect and doesn't report it — because they don't want the hassle, or because the TM is busy, or because they've been here before and nothing gets done anyway — is in a difficult position if that defect later causes a prohibition. So is the operator. The walkaround process only works if the reporting end is trusted and taken seriously.
I've written about the walkaround check in detail in the walkaround check post. For the PMI side, the same principle applies: doing the check is the start. What you do with the findings is what matters.
If you're tired of tracking PMI schedules and defect records in a notebook, ShiftOwt handles the compliance tracking side — including download schedules and rest period monitoring — for £5.99/month for drivers, agency and fleet pricing on request.