October 2027: OBD Trucks Go From Twice a Year to Four Times

The Change Every North Bay Fleet Should Be Budgeting For

Same test, same 90-day window, same compliance fee. Twice the frequency.

The fleets that sort out a tester now won't be calling around in October 2027.

What's Actually Changing

Right now, most non-agricultural diesel vehicles over 14,000 lbs GVWR test twice a year. That's the 2026 schedule and it runs through 2027.

Beginning October 2027, vehicles equipped with on-board diagnostics move to four tests per year. Nothing else about the program changes: you still get the 90-day early submission window, you still pay the annual compliance fee, and non-compliance still means a DMV registration hold.

In practice, OBD-equipped means 2013 and newer diesel engines and 2018 and newer alternative-fuel engines. If your truck takes an OBD scan today, it's in scope.

This is a known, dated change — which makes it one of the few compliance costs you can plan for calmly instead of absorbing as a surprise.

The Short Version

  • Effective October 2027
  • OBD-equipped vehicles: 4 tests per year
  • 2013+ diesel, 2018+ alternative fuel
  • Non-commercial motorhomes: still annual
  • Agricultural vehicles: still annual
  • Opacity-tested engines: still semi-annual

Who's In and Who's Out

Quarterly From Oct 2027

  • 2013 and newer diesel engines
  • 2018 and newer alternative-fuel engines
  • Commercial trucks, buses, heavy equipment haulers
  • Four tests a year, every year

Still Semi-Annual

  • 2012 and older diesel engines
  • These take a J1667 opacity test, not OBD
  • Not included in the quarterly change
  • About opacity testing →

Still Annual

What It Does to Your Numbers

The test fee roughly doubles. At our $80 fleet rate, a 10-truck fleet goes from about $1,600 a year in testing to about $3,200. Add the annual CARB compliance fee of $32.13 per vehicle on top, paid to CARB, and that's your real line item.

But for most fleet managers the money isn't the painful part. The painful part is coordination. Four times a year instead of twice means four rounds of finding a tester, matching trucks to a window, and keeping units available — per vehicle, on staggered deadlines.

That's the case for a standing arrangement rather than four scrambles a year: one tester who already has your VINs, already knows your deadlines, and comes to your yard on a schedule you agreed once.

There's also a capacity issue nobody's talking about yet. In late 2027, demand for credentialed testers in this region roughly doubles overnight. Testers already committed to standing fleet accounts won't have much room for new ones.

What to Do Before Then

  • Inventory engine model years across the fleet
  • Separate OBD units from opacity units
  • Pull every deadline out of CTC-VIS
  • Budget 4x testing for OBD trucks from Q4 2027
  • Lock in a tester on a standing schedule
  • How our fleet program works →

Schedule Your Clean Truck Check

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Common Questions

From October 2027, vehicles equipped with on-board diagnostics move from two tests a year to four tests a year. Everything else about the program — the 90-day early window, the annual compliance fee, the DMV registration hold for non-compliance — stays the same. It's the frequency that changes.

OBD-equipped vehicles, which in practice means 2013 and newer diesel engines and 2018 and newer alternative-fuel engines. If your truck takes an OBD scan today, it's in scope for quarterly testing.

Yes — two meaningful ones. Non-commercial motorhomes and agricultural vehicles stay on their annual schedule. And older engines that take a smoke opacity test rather than an OBD scan are not part of the quarterly change either; they remain semi-annual.

Double your current testing cost, and plan for four scheduling interruptions a year instead of two. For a 10-truck fleet at our $80 fleet rate that's roughly $3,200 a year in testing instead of $1,600. The bigger cost for most fleets isn't the test fee, it's the coordination — which is the argument for having a tester on a standing schedule rather than chasing one four times a year.

Because in late 2027 demand for credentialed testers in this region roughly doubles overnight, and the testers who are already booked solid with standing fleet accounts won't be taking many new ones. Fleets that get on a schedule now keep their slot. Fleets that wait will be calling around in October 2027 alongside everyone else.