If you buy or sell diesel equipment that works in California — or you sell to buyers who do — an engine’s emissions tier is now a value input, not a footnote. California’s amended In-Use Off-Road Diesel rule puts hard dates on when older engines can keep working, and it’s already changing what older machines are worth there.
This rule is genuinely complex — the deadlines depend on fleet size and there are exemptions and exceptions. Treat this as an orientation, not compliance advice, and confirm your fleet’s exact obligations directly with CARB.
The meter still matters, but in California a Tier 0 engine now comes with an expiry date. That changes how an older machine should be priced.
What changed
CARB amended the In-Use Off-Road Diesel-Fueled Fleets Regulation in 2023, with the earliest new requirements starting January 1, 2024, and the U.S. EPA authorized it on January 10, 2025, so it’s enforceable. The headline changes: a phase-out of older-tier engines, a restriction on adding older machines, a renewable-diesel (R99/R100) fuel requirement, and annual fleet reporting.
The tier phase-out schedule
Fleets must stop operating their oldest engines on a rolling schedule that runs from 2024 into the 2030s, staggered by fleet size. Per CARB’s tier phase-out fact sheet:
- Large fleets (over 5,000 hp): Tier 0 engines retired by Jan 1, 2024; Tier 1 by Jan 1, 2026; Tier 2 by Jan 1, 2028.
- Medium fleets (2,501–5,000 hp): Tier 0 by Jan 1, 2026; Tier 1 by Jan 1, 2028; Tier 2 by Jan 1, 2030.
- Small fleets (5,000 hp or under, down to the small tier): Tier 0 by Jan 1, 2028; Tier 1 by Jan 1, 2030; Tier 2 by Jan 1, 2032 — with the smallest fleets running later, into the mid-2030s.
You can’t just add an old machine
The change that most affects a buyer: since January 1, 2024, large and medium fleets generally can’t add off-road vehicles with older engines (Tier 4 Final or cleaner only for those fleets), with restrictions on smaller fleets too. In plain terms, buying an older Tier 3 or earlier machine and putting it to work in a covered California fleet may simply not be allowed — which is a very different buying calculus than in most of the country.
What it means for value
- Older diesel loses runway in California. A Tier 0/1/2 machine has a shrinking legal operating window there, which pressures its in-state resale value and demand.
- Geography matters to price. The same older machine can be worth more to an out-of-state buyer with no equivalent turnover rule than to a California fleet that can’t run it much longer.
- Clean, late-tier machines hold up. Tier 4 Final units sidestep the phase-out entirely and keep their California buyer pool.
Buyer & seller checklist
- Identify the tier and model year of the engine — it’s now part of the machine’s value story, like hours.
- Match it to the deadline for the fleet size and confirm it can still be added or operated where it’s headed.
- Price the compliance risk in — the same way you would a worn undercarriage. Our buying checklist and valuation guide cover the rest.
- Verify with CARB. The exemptions and size brackets are detailed — don’t rely on a summary for a compliance decision.
Sources & references
Last updated .