Marcus Reid

Diesel Technician & Senior Contributor

Marcus spent two decades in independent diesel shops before moving into writing, working mostly on Power Stroke, Cummins and Duramax pickups along with the RVs and farm equipment that came through the same bays. At USA Diesel Finder he covers diagnostics, DPF and emissions systems, and the practical side of choosing a shop — what a fair estimate looks like, which symptoms can wait, and which ones can't. His goal is to give owners enough context to have a confident conversation with their mechanic.

Articles by Marcus Reid

Rear view of a large tanker truck transporting fuel on a highway, emphasizing logistics and transportation.
Emissions & DPF
6 min read

What Is a Particulate Trap? Diesel Emissions Filter Explained

A particulate trap is the diesel filter that catches soot before it leaves the tailpipe. Here's how it works, how it clears itself, what cleaning or replacement costs, and why deleting one is illegal.

How Long Does DEF Last? Consumption and Shelf Life Explained
Emissions & DPF
7 min read

How Long Does DEF Last? Consumption and Shelf Life Explained

Unopened DEF lasts about 1 year in warm storage and up to 2 years when kept cool. Learn real DEF consumption rates, storage rules, and how to spot fluid that's gone bad before it hurts your SCR system.

How Long Does a DPF Regen Take? Passive, Active & Forced Times
Emissions & DPF
8 min read

How Long Does a DPF Regen Take? Passive, Active & Forced Times

A passive regen finishes in the background during highway driving with no dash warning. An active regen takes 20-40 minutes, and a forced shop regen runs 45-90 minutes. Here's what changes the timeline and when to stop driving.

Black pickup truck emitting smoke during a burnout on the road.
Emissions & DPF
6 min read

How Much Does DEF Fluid Cost? 2026 Price Guide

DEF fluid runs about $3 to $4 a gallon in jugs, or less than half that in bulk at truck stops. This guide breaks down pump prices, bulk tank costs, and how to avoid overpaying for diesel exhaust fluid in 2026.

Row of parked semi trucks in a rainy lot, captured in a dramatic black and white setting.
Emissions & DPF
9 min read

Regen Meaning: Active, Passive and Forced DPF Regens Explained

Regen meaning, in plain terms: it's how a diesel truck burns off soot trapped in its DPF. This guide breaks down passive, active and forced regens, what triggers each one, how long they take, and what to do when a regen fails or won't complete.

Vintage classic trucks of different colors parked in row on asphalt road against green trees
Emissions & DPF
7 min read

DPF Filter Cleaning Cost: What Diesel Owners Pay in 2026

DPF filter cleaning cost runs about $300 to $900 depending on method, while full replacement can hit $2,000 to $4,000+. Here's what drives the price, when cleaning beats replacement, and how to avoid a bigger bill down the road.

Aerial view of a truck stop with gas station and parking lot under a clear blue sky.
Emissions & DPF
7 min read

Is DEF Going Away? What the 2027 EPA Rules Really Mean

DEF isn't disappearing — EPA's tighter NOx rules actually lock SCR and DEF systems in for years to come. Here's what's changing, what isn't, and how it affects your truck, RV, or fleet.

Mechanics working on a truck in a workshop, focused on repair and maintenance.
Emissions & DPF
8 min read

EGR Valve Change: A Practical Guide to Service & Cost

An EGR valve change runs about $250-$900 for parts and labor, though cleaning a stuck valve can cost far less. Here's how to tell if you need cleaning or full replacement, what a shop does during service, and why deleting an EGR valve is illegal under the Clean Air Act.

DPF Filter Guide: How It Works and When to Service It
Emissions & DPF
6 min read

DPF Filter Guide: How It Works and When to Service It

A DPF filter traps soot from diesel exhaust and burns it off through regeneration. Learn how the system works, warning signs of a clog, service intervals, and real 2026 cleaning and replacement costs.