Forced Regeneration Services
After-Treatment & Forced Regeneration Diagnostics for Semi-Trucks
Struggling with SCR/DPF faults, derates, or a failed parked regeneration? We diagnose and repair the full after-treatment system — NOx sensors, DOC/DPF/SCR units, DEF pumps, temperature sensors, turbo actuator issues, and more. Fast mobile
service for semi-trucks and trailers only!
After-Treatment Diagnostic
Forced Regeneration Services
Mobile Diesel Repair LLC — Serving Semi-Trucks & Trailers Only
Modern emissions systems are complex, and a single fault in the after-treatment chain can quickly lead to engine derates, reduced power, or a truck stuck at 5 mph. We specialize in diagnosing and repairing the entire SCR/DPF system — including DOC, DPF, SCR units, DEF systems, sensors, and VGT turbo control issues — using professional OEM-level software and equipment.
Our mobile service brings full dealership-level diagnostics straight to your truck, whether you’re running Cummins, Detroit, International, Paccar, Volvo, Mack, or Freightliner. We do not work on diesel pickup trucks — semi-trucks only only.
Comprehensive After-Treatment System Diagnostics
We troubleshoot every component that affects the DOC, DPF, and SCR system, including:
• DOC (Diesel Oxidation Catalyst)
DPF (Diesel Particulate Filter)
SCR (Selective Catalytic Reduction)
NOx sensors (inlet & outlet)
Temperature sensors
DEF pump, heater, and pressure
Turbo VGT actuator & boost issues
Ambient air temperature sensors
EGR valve performance
Coolant flow to the DEF system (winter freeze protection)
Even something simple — like a bad battery connection, blown fuse, weak ground, or low coolant — can prevent your truck from performing a regeneration.
Sometimes the repair is major, such as a failed DPF, clogged DOC, or a full SCR box replacement.
SCR Box vs. Separate Components
Freightliner: SCR and DOC/DPF are welded together inside the SCR box — the entire unit must be replaced if it fails.
Kenworth / Peterbilt / International / Volvo / Mack: Components are separate, so we can replace only what’s needed (DOC, DPF, or SCR).
Whenever possible, we recommend replacing the system as a set for maximum reliability and to prevent repeat failures.
OEM-Level Software Diagnostics
We use multiple factory-level diagnostic programs depending on your engine:
Cummins Insite
Detroit DDDL.8 (2025)
JPRO & E-Technician
Launch HD scanner (all heavy-duty engines, 12–24V systems)
we can connect to J1939 port, 6-pin diagnostic port and OBD-II port. While most heavy-duty trucks do not rely on it, some manufacturers like Volvo and Mack have added the standard 16-pin OBD-II connector to their newer trucks.
We only service semi-trucks and trailers — no diesel pickup trucks.
Our Forced Regeneration Process
A forced regeneration is not a repair by itself, it is the final step after confirming that all components are working correctly.
Before we start a forced regeneration, we
Connect professional diagnostic software
Check DEF pump operation & pressure
Test DEF fluid quality
Inspect DEF filters & heater function
Verify coolant temperature and fuel level
Check for leaks or damage
Confirm turbo VGT actuator operation
Verify NOx, temperature, and differential pressure sensor data
Review all active and inactive fault codes
Ensure the engine is at proper operating temperature
Conditions that will prevent a parked regenstation
Low coolant
Low fuel
Bad NOx sensor
Faulty ambient air temperature sensor
Stuck EGR valve
Failed turbo actuator
Insufficient exhaust temperature
DEF system pressure faults
Frozen DEF components (winter coolant flow issues)
Why parked regeneration fail
If your truck refuses to do a parked registration, it means something is wrong. A forced registration might get you going temporarily, but 80% of the time a deeper issue is the real cause.
Clear Codes — When Possible
Sometimes codes can be cleared after repairs or a regeneration, sometimes they cannot.
Either way — the customer is responsible for the minimum diagnostic time once we complete the work requested and explain the results. We always discuss the process and costs with you before performing any work.
Minimum Computer Diagnostic Fee
We charge a two-hour minimum for diagnostic and computer time.
This includes:
Complete system scan
Full after-treatment diagnostic
Pressure and quality checks
Forced regen attempt (if conditions allow)
Detailed explanation of findings
