Merlo Tech Talk: Understanding ReGen

Merlo Tech Talk: Understanding ReGen


ReGen-Regeneration. The chemical process of ‘baking’ or cooking accumulated soot out of the diesel particle filter (DPF) or the Selective Reduction Catalyst (SRC).  Merlo telehanders are equipped with either the DPF or the SRC.

How to tell if your Merlo has a Diesel Particle Filter:

If you see this button on the control panel, your Merlo is non-passive.  When the machine ‘calls’ for a ReGen, it will need operator assistance to start the process.  .

Merlo’s ReGen Process.

Merlo telehandlers (including Rotos) with DPF are non-passive. This means when a machine ‘calls’ for a ReGen — certain critera are met and the system is ‘dirty enough” – the operator must manually push the ReGen button to request the process. 


  1. Fully warmed up machine (ideal temp: 284°F/140°C)
  2. In park
  3. In neutral.

Dirty enough means something different for each engine manufacturer.

Why is there ReGen?  Simply, Emissions. ReGen reduces the number of particles and the oxides of nitrogen (NOx) from releasing into the atmosphere from burning diesel fuel.

When emission sensors ‘make the call’:

  • Dashboard symbol lights up
  • ReGen switch/button light activates
  • Audible beep is activated. This will continue until the ReGen button is engaged.

To activate ReGen:

  • Push and hold button for two seconds
  • Machine will/should idle up to 15-18K rpm (this is a generalization)
  • Once idle is up, leave machine alone until it idles down to what is normal for your machine.
ReGen takes as long as the telehandler says it needs. 10 minutes? Longer? The duration depends on how dirty the Diesel Particle Filter is.

TheReGen process is very important:

ReGen notifications (visual and audible) cannot be ignored. If ignored, the telehandler will derate (reduce functionality) and eventually become inoperable.

If this happens, it will be up to the engine manufacturer to fix the problem.

Selective Reduction Catalyst (SRC). The other Merlo emissions system.

The other  emission system Merlo uses is Selective Reduction Catalyst (SRC).  An SRC system is passive. Many newer Merlo’s are arriving equipped with this set up. This is an automatic ReGen; when the machine is in operation, and the sensors call for a ReGen, it will occur automatically, without any action/interaction from the operator.

Unlike the DPF ReGen call, SRC will activate indicators, such as lit dash symbols, only if there is an issue with the system.

How do you know if the system is in ReGen, both non passive and passive? When you step out of the cab, there will be a distinctive odor of urea (otherwise known as urine).

The Take Away.

Merlo models with the ReGen button on the dash means you have a non-passive ReGen system. When the machine call for a ReGen, it is the operator’s responsibility to start the ReGen process.

Click here for the ReGen chart explaining dashboard symbols and action requirements.

More info can be found in the Instruction Manual. Controls and Instruments. Module 1. Section 3. Emission Control System

Still have questions?

Please call our service advisors: 803-327-4949
Monday-Thursday 7:00 AM-3:45 PM and Fridays 7:00 AM-3:15 PM.

After hours cell phone:  704-288-9225

If you are missing the operator manual and would like a copy, please contact our parts department.

During business hours:  803-327-4949


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