PM Schedule B is the intermediate service tier that catches what basic safety inspections miss — developing engine problems, driveline wear, electrical degradation, and fluid contamination that won't show symptoms until they become expensive failures. While Class A inspections handle the essentials every 5,000-10,000 miles, PM-B goes deeper into engine diagnostics, driveline components, and fluid analysis at 10,000-20,000 mile intervals for heavy-duty vehicles. According to J.J. Keller, a PM-B should include all PM-A items plus an oil and filter change, an ECM download with action on trouble codes, and more in-depth checks of engine and driveline components. This is the service level that bridges the gap between "truck looks fine" and "truck actually is fine" — the difference between reactive breakdowns and proactive maintenance that extends component life and prevents the $4-$8 cost multiplier of emergency repairs. This guide provides the complete PM-B checklist organized by system, explains when to schedule it, covers OEM-specific interval variations, and shows how to integrate PM-B findings into your overall maintenance program.
Where PM-B Fits in the Service Tier
PM-B is the second tier in a four-level preventive maintenance framework. Each tier includes everything from the previous level plus additional items — so a PM-B includes all PM-A checks plus the engine, driveline, and electrical diagnostics that make it an intermediate service rather than just a safety check.
A
Safety Inspection
Every 5,000-15,000 mi
Brakes, tires, lights, fluids, belts, air system
B
Intermediate Service
Every 10,000-20,000 mi
All PM-A + engine diagnostics, driveline, ECM download, oil analysis, electrical, exhaust
C
Comprehensive Service
Every 50,000-60,000 mi / annual
All PM-B + transmission, differential, brake overhaul, alignment, DOT annual
D
Major Overhaul
Every 100,000+ mi
All PM-C + engine/transmission/axle rebuild, frame inspection, cab refurbishment
OEM B-Service Interval Variations
Freightliner / Western Star
B-Service every 30,000 mi
Peterbilt / Kenworth
PM-B every 25,000 mi
International
B-Service every 45,000 mi
General Fleet Practice
10,000-20,000 mi (heavy-duty)
Always check your specific OEM manual. Severe duty (construction, stop-and-go, mountain) may require 15-25% shorter intervals.
Complete PM-B Checklist by System
This checklist includes all PM-A items (which PM-B inherits) plus the additional items specific to PM-B. Organized by vehicle system for efficient technician workflow. Total service time: 2-3 hours. Estimated cost: $500-$1,200 depending on oil analysis and filter replacement needs. Items marked with a filled checkbox are PM-B additions; outline checkboxes are inherited PM-A items.
Oil and filter change (use OEM-spec oil weight and filter)
ECM download — review and action all stored trouble codes
Oil sample for analysis (send to lab — wear metals, contamination, viscosity)
Fuel filter inspection / replacement (per OEM interval)
Air filter inspection — replace if restricted or at OEM interval
All fluid levels: coolant, power steering, windshield, DEF
Coolant concentration and pH test (refractometer + test strip)
Belt condition and tension check
Turbocharger boost check (if equipped)
DPF status / regeneration history review
Driveshaft inspection — runout, balance, yoke wear
U-joint condition — check for play, binding, lubrication
Transmission fluid level and condition (color, smell, debris)
Transmission mount and connection integrity
Axle seals — check for leaks at hubs, pinion, and axle shafts
Differential fluid level check
Clutch adjustment / release bearing check (manual trans)
Brakes & Air System
PM-A + PM-B
Brake lining / pad thickness measurement (all positions)
Slack adjuster travel and automatic adjustment test
ABS system diagnostic — check for stored codes and lamp operation
Air system leak test (governor cut-in/cut-out, buildup time)
Air dryer cartridge condition and drain valve operation
Brake drums / rotors (scoring, cracks, wear limits)
Brake chamber and pushrod inspection
Suspension & Steering
PM-B Core
Shock absorber condition and mount integrity
Spring pack inspection — cracked, broken, shifted leaves
Air bag condition (cracks, leaks, mounting)
Steering linkage play and wear (tie rod ends, drag link, pitman arm)
King pin wear check (steer axle)
U-bolt torque verification
Power steering fluid level and condition
Electrical System
PM-B Core
Alternator output test (voltage and amperage under load)
Starter draw test
Battery load test and terminal condition
Wiring harness inspection — chafing, corrosion, heat damage
All lights and signals functional test
Ground connections clean and tight
Exhaust & Emissions
PM-B Core
Exhaust system leak check (manifold, turbo connections, piping)
DPF backpressure reading (compare to baseline)
DEF system — tank level, dosing valve, injector condition
EGR valve operation check
Exhaust clamp and hanger condition
Tires & Wheels
PM-A + PM-B
Tread depth measurement (gauge, 3 points per tire)
Inflation pressure (calibrated gauge, all positions)
Wear pattern analysis — document for alignment/suspension diagnosis
Sidewall condition (cuts, bulges, weathering)
Wheel bearing play check and repack evaluation
Lug nut torque verification
Hub seal condition — oil leaks, contamination
HVI provides customizable PM-B templates with every item above — add, remove, or modify items for your specific equipment. Photo-required fields ensure technicians actually inspect, not just check boxes.
Book a demo to see PM-B templates. Or
start free.
Oil Analysis: The PM-B Intelligence Layer
Oil analysis is the single highest-value diagnostic activity in a PM-B service. A $25 lab test reveals engine conditions that would cost thousands to diagnose otherwise — and catches developing failures 10,000-30,000 miles before they cause breakdowns.
What Oil Analysis Reveals
Wear Metals
Iron, copper, aluminum, chromium levels indicate which components are wearing. Rising iron = cylinder liner or camshaft. Rising copper = bearings. Trending data across samples catches problems early.
Contamination
Coolant (glycol/sodium), fuel dilution, dirt/silicon, soot loading. Coolant in oil = head gasket or liner failure. Fuel dilution = injector or ring problems. Dirt = air filter or intake leak.
Oil Condition
Viscosity, TBN (Total Base Number), oxidation, nitration. Shows whether oil still protects the engine or needs replacement. Can validate or extend drain intervals based on actual condition.
Interval Optimization
If oil analysis consistently shows acceptable condition at current drain interval, you may safely extend — saving $200-$400 per service. If contamination appears early, shorten intervals to protect the engine.
PM-B Findings: Fix, Schedule, or Monitor
Not every PM-B finding requires immediate repair. A structured triage categorizes findings by urgency — preventing both over-maintenance (replacing things with remaining life) and under-maintenance (ignoring developing problems).
Fix Now — Before Dispatch
Any FMCSA OOS condition (brakes, tires, lights, air)
Oil contamination (coolant, excessive fuel dilution)
Active ECM fault codes affecting derate or shutdown
Air system leak exceeding 3 PSI/min drop rate
Brake lining approaching minimum thickness
Steering play exceeding limits
Schedule — Next 30 Days
Rising wear metals in oil (trending, not critical)
Belt or hose showing early deterioration
Suspension components with measurable wear
U-joints with slight play (not binding)
Battery showing marginal load test
Exhaust clamp loosening or minor leak
Monitor — Track at Next PM
Oil consumption rate (document level each PM)
Tire wear patterns developing (not irregular yet)
Minor coolant concentration drift
DPF backpressure slightly above baseline
Stored ECM codes that cleared, not returned
Hub seal weeping (not actively leaking)
HVI's digital PM-B automatically routes "Fix Now" findings to work orders, schedules "Next 30 Days" items, and flags "Monitor" items for comparison at the next service.
Book a demo to see the triage workflow.
Digitizing PM-B Workflow
Paper PM-B checklists produce checkmarks. Digital PM-B checklists produce data — measurements, photos, trends, and audit trails that make the inspection meaningful and the maintenance program improvable.
Guided Workflow
System walks technician through PM-B items in logical order by vehicle zone. Required fields prevent skipping. Measurement fields require actual values — not just pass/fail.
Photo Documentation
Photo gates on key items (belt condition, tire wear, brake lining, fluid color) prove the technician actually inspected. Photos capture baseline for comparison at next PM-B.
Automatic Work Orders
"Fix Now" findings generate work orders immediately. "Schedule" items create dated follow-up tasks. "Monitor" items flag for comparison at next PM. Nothing falls through the cracks.
Trend Analysis
Compare PM-B measurements across services: brake lining wear rate, oil consumption trends, DPF backpressure progression, tire wear per 10K miles. Spot vehicles drifting toward failure.
CSA Vehicle Maintenance Split Affects PM Quality
The February 2026 CSA overhaul splits Vehicle Maintenance into "Standard" and "Driver Observed" categories. PM-B quality directly affects Standard — poorly maintained engines, drivelines, and electrical systems found at roadside score here. Documented PM-B programs with consistent OEM-interval service produce measurably better scores.
Book a demo to see CSA tracking.
eDVIR + Digital PM: Closed-Loop Maintenance
With eDVIRs officially authorized effective March 23, 2026, driver findings flow directly to PM-B queues. A driver notes engine noise Monday — by Tuesday it's on the next PM-B work order. No paper handoff, no lost information.
FMCSA Audits Require Documented PM Tiers
49 CFR 396.3 requires "systematic" maintenance. In 2025-2026, auditors specifically ask for tiered PM schedules (A/B/C/D) with documented intervals and adherence proof. Carriers showing only oil changes without intermediate PM-B service are cited. Average penalty: $7,155 per violation.
Oil Analysis Adoption: Data-Driven Drain Intervals
More fleets are moving from fixed drain intervals to condition-based intervals using oil analysis at every PM-B. Labs report 48-hour turnaround, trending software compares results, and fleets report 15-25% fewer unplanned engine repairs.
PM-B Is Where Problems Get Found Early
Class A catches the obvious. Class C is the annual deep dive. PM-B catches developing problems — engine wear, driveline degradation, electrical decline, fluid contamination — while they're still cheap to fix. The 2-3 hours and $500-$1,200 invested in a thorough PM-B save 10-50x in avoided emergency repairs, towing, and downtime. Add oil analysis and you have the most cost-effective diagnostic in fleet maintenance.
Build PM-B Into Your Fleet's Rhythm
HVI provides customizable PM-B templates with guided technician workflow, photo requirements, measurement fields, automatic work order generation, and trend analysis across services.
Frequently Asked Questions
Q: How often should PM-B service be performed?
For heavy-duty vehicles: every 10,000-20,000 miles. OEM intervals vary — Freightliner at 30,000 mi, Peterbilt/Kenworth at 25,000 mi, International at 45,000 mi. Severe duty should reduce by 15-25%. Light-duty uses 3,000-5,000 mile intervals. Always consult OEM manual and adjust based on oil analysis.
Q: What's the difference between PM-A and PM-B?
PM-A is a basic safety inspection (brakes, tires, lights, fluids). PM-B includes all PM-A items plus oil/filter change, ECM diagnostic download, oil sample for lab analysis, driveline inspection (driveshaft, U-joints, transmission), electrical system testing, exhaust/emissions checks, and fluid condition analysis. PM-B catches developing engine and driveline problems that PM-A misses.
Q: What does an ECM download reveal during PM-B?
The Engine Control Module stores fault codes, performance data, and diagnostics invisible to visual inspection. Active codes indicate current issues. Stored/cleared codes show intermittent problems. Performance data (boost pressure, exhaust temperature, fuel trends) reveals developing problems before they trigger a code. Every PM-B should include ECM download with action on all findings.
Q: Is oil analysis worth the cost at every PM-B?
At $20-$30 per sample, oil analysis is the highest-ROI diagnostic in fleet maintenance. It reveals wear metals, contamination, and oil condition — catching problems 10,000-30,000 miles before failure. One prevented engine failure ($15,000-$40,000) pays for thousands of samples. Fleets with consistent analysis report 15-25% fewer unplanned engine repairs.
Q: How long does a PM-B service take?
A thorough PM-B takes 2-3 hours for a standard tractor — all PM-A items (1-1.5 hours) plus PM-B additions (engine diagnostics, driveline, electrical, oil change). Digital checklists with guided workflow reduce time by 20-30% vs paper.
Start free with HVI digital PM templates.
Q: What PM-B findings require immediate repair vs. monitoring?
Immediate: any OOS condition, oil contamination, active ECM codes, air leaks over 3 PSI/min, brake lining near minimum. Schedule within 30 days: rising wear metals, early belt/hose deterioration, U-joints with slight play, marginal battery. Monitor at next PM: oil consumption trending, minor coolant drift, cleared ECM codes, weeping hub seals.
