Service · Emissions
DEF & After-Treatment Service in Jackson, MS
A derated truck doesn't make money. Wilkerson's keeps DEF and after-treatment work in-house in Jackson, MS — most shops in central Mississippi send these jobs out because they don't have the tools, the training, or the patience to chase emission-system faults. We do.
Modern diesel after-treatment (DEF dosing, SCR catalysts, NOx sensors, DPF interaction) is where post-2010 engines spend most of their fault-code budget. When the DEF heater quits, when the SCR efficiency drops below the EPA-mandated floor, when the NOx sensor reads wrong, the truck derates and the dash lights up. We diagnose it on the truck, fix it with the right part, and clear the code.
We do not perform illegal DPF or DEF delete work. We are an EPA-compliant shop — when we say we fixed it, the truck is legal and the warranty is intact.
What's included
Everything we do on a def / after-treatment visit.
DEF dosing system diagnosis & repair
Dosing valves, pumps, heaters, supply modules — when the system stops injecting, the truck derates.
DEF tank & line work
Crystallization, freeze damage, level sensor faults, leaking lines, tank heater failures.
SCR catalyst diagnostics
Efficiency testing, catalyst replacement, related sensor work.
NOx sensor replacement
Inlet and outlet NOx sensors — common failure, real driver of derate codes.
DPF interaction & regen support
Forced regens, back-pressure data, sensor diagnostics. (Deep DPF work lives on our DPF page.)
Fault-code diagnostics
Full SPN/FMI pull and live data. We don't guess the part — we read the truck.
Annual after-treatment health check
Available as part of fleet PM programs — catch the failure before the derate.
Signs you need this
When to call us.
Most of these symptoms point to the work on this page. A few point somewhere else — and we'll tell you straight either way.
- Check-engine light with SPN 3361, 3364, 3216, 3226 or similar after-treatment codes
- Truck derated to 5 mph or 55 mph
- DEF gauge stuck at one level or jumping
- Crystals around the DEF tank or lines
- “DEF quality poor” or “See dealer” warning
- SCR efficiency low warnings on the dash
Pricing & estimates
No surprises on the invoice.
Diagnostic starts with a full code pull and live-data session on the truck. Written estimate before any parts. Repairs covered by our own written warranty — we stand behind every covered repair.
Our process
No surprises between the call and the invoice.
Four steps from the first call to the keys back in your hand. No mystery, no upsell theater.
- 01/Step
Call us
A real person answers the phone. We'll tell you straight whether your job is in scope and book you in if it is.
- 02/Step
Written estimate
We diagnose and write up the work before we touch anything billable. You see the price and the parts before you approve.
- 03/Step
You approve
Nothing happens without a green light from you. If we find more during the repair, we stop and call before we keep going.
- 04/Step
Repair + written warranty
Same name on the invoice every time. Our own written warranty on covered work — and the family promise behind it.
Why Wilkerson's
Three reasons people keep coming back.
- Not sent out
- In-house
- Compliant only
- EPA
- If it spreads
- Same shop
Most shops in this market send DEF work to the dealer or a specialty shop. We diagnose and repair in-house — faster turnaround, no double-handling.
We do not perform illegal delete work. When we fix your after-treatment system, the truck is legal and emissions are intact.
After-treatment failures sometimes hide engine problems. We're the shop that does both — no “you'll need to take it somewhere else.”
Frequently asked
What people ask before they bring the truck in.
Tap any question to expand the answer.
Most of the time, yes. Bring the truck in — we'll pull codes, check DEF supply and sensors, and most after-treatment derates clear inside a day once we've got the right part. Call ahead so we can pre-stage parts.
They're a tightly-toleranced emissions part with a short warranty and a real failure rate. We stock the common ones and quote you up front — no markup games. If it's still under engine warranty, we'll point you to the right path.
No. Delete work is illegal under the Clean Air Act, voids your engine warranty, and will fail any DOT inspection. We're an EPA-compliant shop. We can clean a DPF, replace a clogged one, or fix what's actually broken upstream.
API-certified DEF only — sourced through our heavy-duty truck parts suppliers. Available in 2.5-gallon and 55-gallon for fleet refills at the parts counter.
Yes. Fleet PM programs include an after-treatment health check — sensor data, fault history, DEF quality. Catch the failure before the derate.
Most of the time, yes. Bring the truck in — we'll pull codes, check DEF supply and sensors, and most after-treatment derates clear inside a day once we've got the right part. Call ahead so we can pre-stage parts.
No. Delete work is illegal under the Clean Air Act, voids your engine warranty, and will fail any DOT inspection. We're an EPA-compliant shop. We can clean a DPF, replace a clogged one, or fix what's actually broken upstream.
Yes. Fleet PM programs include an after-treatment health check — sensor data, fault history, DEF quality. Catch the failure before the derate.
They're a tightly-toleranced emissions part with a short warranty and a real failure rate. We stock the common ones and quote you up front — no markup games. If it's still under engine warranty, we'll point you to the right path.
API-certified DEF only — sourced through our heavy-duty truck parts suppliers. Available in 2.5-gallon and 55-gallon for fleet refills at the parts counter.
DEF / After-treatment done right. Call us.
Mon–Fri · 7am–5pm · Saturday · 7am–12pm