DPF/DOC/SCR Cleaning

SCR Cleaning & Troubleshooting

MobileDPFCleaning has successfully cleaned SCRs and helped customers avoid costly replacements.

Common SCR Problems

DEF Dosing Module Issues
One of the most common problems we see is a faulty Diesel Exhaust Fluid (DEF) dosing module.

• Over time, white caked powder residue can build up inside the SCR, clogging it and triggering fault codes.

• The DEF dosing module determines how much DEF fluid to inject based on readings from the NOx sensors (Nitrogen Oxide sensors).

• This module contains both a pump and a spray nozzle, spraying DEF fluid into the exhaust stream between the DPF and SCR.

Proper Setup Matters
For accurate operation, 24″–30″ of exhaust tube (with mixing baffles) is required to properly mix DEF with the exhaust gases. If the module fails, it can underdose or overdose, causing downstream issues and SCR inefficiency.

Severe SCR Damage

Coolant-Soaked SCRs
SCRs that are contaminated with coolant or oil are often beyond recovery. These events can poison or deactivate the SCR, preventing proper Selective Catalytic Reduction.

SCR Wear & Lifespan
Even under normal conditions, SCRs wear out over time, typically between 600,000 – 800,000 miles, according to manufacturers.
Think of it like tires: even with care, they eventually wear down.