Free API
Help
2018 RAM 3500
6.7L I6 Cummins•RWD•diesel•ISB•turbo
11 active safety recalls on this vehicle — view recalls
Founding sponsor spot is openYour name on every procedure for this vehicle, permanently.Sponsor — $99 →
Repairs0Labor515Torque136Fluid9DTC1795Battery1Maintenance0Recalls11
P3881high severityPowertrain

Lean NOx Trap (LNT) Desulfation Failure

on 2018 Ram 3500 6.7L I6 Cummins · RWD

What this code means

The lean NOx trap desulfation process has failed to restore NOx conversion efficiency. The LNT requires periodic high-temperature desulfation to remove sulfur compounds.

Symptoms

  • Check Engine Light
  • Increased NOx emissions
  • LNT warning
  • Failed emissions test
  • Reduced power may occur
  • Fuel economy decrease from failed desulfation attempts

Common causes

  • Fuel sulfur content too high
  • LNT catalyst degradation
  • Exhaust temperature insufficient for desulfation
  • Fuel injection issue during desulfation
  • LNT poisoned beyond recovery

Diagnostic steps

  1. Check LNT NOx efficiency before and after desulfation attempt
  2. Monitor exhaust temperature during desulfation
  3. Check fuel quality
  4. Inspect fuel injectors for desulfation function
  5. Review desulfation attempt history

Repair notes

Attempt forced desulfation at controlled temperatures. Replace LNT if desulfation cannot restore efficiency. Use ultra-low sulfur diesel fuel.

🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Budget handheld~$40
ANCEL AD410 →
No-phone-needed handheld — reads, clears, live data, freeze frame.
✓ ANCEL official store
Serious DIY~$100
BlueDriver Pro →
Enhanced codes (ABS, airbag, TPMS) plus repair reports.
SHOP FAVORITE
Shop-grade tablet~$300
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
✓ Autel official store
Pro diagnostics$1,500+
Autel MaxiSys MS906 Pro →
Full-system pro platform — topology mapping, ECU coding, the works.
✓ Autel official store
As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.

Other Powertrain codes on this vehicle

🔌 Need this data in your app? It's all in the free API →
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years. Spot an error? Use the Help link above — a human reads every report.
Stuck on this repair? Take it to The Diag Desk — ask a master tech about this exact car → real human answer within 24h, never AI
Share:XRedditFBWhatsAppThreadsEmail
⚠ STILL BEHIND THE PAYWALL
The 2018 Ram 3500 repair data is incomplete because no one has sponsored it yet. For $99, we generate the full step-by-step procedures, then fact-check them with a second AI pass and your expert review. Your name on every procedure, permanently.
The same data would cost $169/mo from Mitchell1 or $30/year from ALLDATAdiy — and you'd be renting access, not freeing it. Sponsor once, free forever.
Sponsor the Ram 3500 — $99 →
Building an app?
Free API access to all this data — 10 requests/day, no card required.
Get an API key →
Run a shop?
Manage repairs, estimates, and customers with ShopBase — $249/mo, all features included.
Try ShopBase →