Parts availability is improving, but timing diagnostics still painful

The supply chain disruptions that defined the 2021–2023 service market have largely worked through the system. Routine parts — filters, rotors, belts, sensors, brake hardware — are back to pre-pandemic availability at most distributors. NAPA, AutoZone Commercial, and O’Reilly all reported improved fill rates in their most recent earnings calls, with nationwide same-day fill rates above 85% for their top 50,000 SKUs.

The remaining friction is concentrated in two areas: late-model OEM dealer-only components and programmable modules.

Where the delays remain

Control modules — engine control modules, transmission control modules, body control modules — remain a persistent problem. The semiconductor shortage is technically over, but the allocation and distribution pipeline for programmed replacement modules has not fully normalized. Shops report waiting 5–18 days for module replacements on some late-model domestic and import platforms, and in some cases longer for specialty applications.

The secondary problem is programming. Even when the module arrives, it requires VIN-specific programming before installation — which means either a J2534 passthrough subscription with OEM-level access or a trip to the dealer’s service lane. Shops without J2534 capability are increasingly routing affected jobs to dealers or paying a mobile programming service, adding $75–$150 per job and 1–3 days to cycle time.

Timing components for certain import platforms — timing chains, tensioners, and water pumps on specific GM 2.5L and Ford 2.0T applications — also showed elevated lead times in Q3 2025. Shops doing volume work on those platforms should carry deeper safety stock than they did two years ago.

What shops are doing differently

The shops reporting the least disruption share a common trait: they shifted parts ordering earlier in the diagnostic process. Rather than waiting for a confirmed diagnosis before sourcing, they now identify probable parts after the initial inspection and pull availability before committing a bay. Jobs that require a module or uncommon OEM part are scheduled 3–5 days out; jobs with standard aftermarket availability are scheduled same-day or next-day.

It is a small workflow change with a meaningful impact on bay utilization. A job sitting in a bay waiting for a part is a bay that could be doing other work.