How to Regen a Freightliner (SOLVED!)


Truck owners must be familiar with the regeneration process since the EPA’s emission control technology regulations came into effect for diesel-powered engines.

STEP 1: What Type of Regeneration should you perform?

Now that you are aware of the need for regeneration, what type of regeneration should be performed?

  1. When regeneration is urgently needed, parked regeneration: If one of your warning lights indicates that renewal is required immediately, as explained above,
  2. Passive Regeneration is when the truck moves at a regular speed.

iii. Active Regeneration occurs when the truck moves at high speeds.

How to Regenerate a Freightliner with Different Types of Regeneration: Passive, Active, and Parked

We’ll be discussing the three types and details of how to do a parked regen on a Freightliner truck equipped with a Detroit diesel engine.

1. Parked Regeneration (Stationary)

When the truck is stationary or parked, regen refers to cleaning the DPF at a standstill.

After you have read the information above about identifying warning lamps, you will be able to identify when parked regeneration is required and when you can use the active option.

Also, if you receive error codes indicating that immediate regeneration is required, it may be a good idea to park your Freightliner for parked regeneration.

Here is how to regen Freightliner using the parking/static method.

  • Slowly idle the engine for a few seconds before turning it on. It should not be in a power-take-off mode.
  • Move the transmission from neutral to neutral, then back into neutral.
  • Change the parking brake setting from OFF to ON.
  • Release the clutch pedal by pressing and releasing it
  • For five seconds, hold the DPF switch in the ON position. Then release the button. The engine speed will increase (RPM), and the DPF warning light will disappear.
  • The parked regen process is currently in progress and should take approximately 40 minutes.
  • You should not press the ignition switch to turn off the engine, push the clutch or shift the truck into gear to stop the regeneration if you do any of these things.
  • The regen will be complete when the engine is slow idle. The DPF light will still be on.
  • Regeneration can increase exhaust temperature, so make sure you do it outside away from any flammable or combustible material. You should now be able to do a parked regen.

Active Regeneration

Active regeneration refers to the process of burning the soot using heat from outside energy sources such as the truck’s electricity or heated diesel fuel.

How To Do Active Regeneration?

It only requires that the driver brings the vehicle to highway speeds. No further action is required. How does it work? Simply put, the sensors will sense that it is necessary to regenerate and will automatically inject fuel to raise the temperature of your DPF.

The high-temperature fuel is then injected to burn off the accumulated soot. An oxidizing catalyst in some trucks can perform this process. It should be checked and cleaned as necessary. An active regen takes between 40 and 45 minutes on the highway.

If the duty cycle doesn’t produce sufficient exhaust temperatures, the DPF can become clogged with soot. The pressure sensors indicate this. The DPF will need to undergo active regeneration. Active regeneration is when raw fuel is injected into a diesel oxidation catalyst to reach the appropriate DPF regeneration temperatures. Passive regeneration and dynamic generation do not require input from the vehicle operator. Passive regeneration does not require checking engine light codes shown on the vehicle dashboards.

3. Passive Regeneration

Passive regeneration is when the truck maintains the proper exhaust temperatures for the DPF to self-regenerate continuously. This regeneration continues as the driver drives the truck as usual.

Most vocational trucks are designed for off-road use, such as logging and oilfield vehicles. Passive regeneration is most common in these trucks and can occur without the operator doing anything.

For five (5) seconds, hold the DPF switch in the ON position. Then release the button. A Parked Regeneration will stop if the key is in the ON position, the truck is moved into gear, or the parking brake is removed.

Passive regeneration is a method to oxidize particulate matter in the diesel particulate filter. This type of regeneration is a more efficient method than high-temperature active regeneration. It uses average exhaust temperatures and nitrogen dioxide (NO2) to oxidize PM within the DPF. The simplicity of passive regeneration is a benefit to operators. It requires fewer components, making it lightweight and easy to install.

How to tell if your Freightliner needs regeneration

 First Method: Error/Fault Code Lamps

First, identify the time when a regeneration (regen) is required. Watching for warning lights or errors on your truck’s dash is the best way to keep track of your diesel particulate filters status and when regeneration is required.

Excessive exhaust soot overburdening the DPF causes your DPF to regenerate. The result of incomplete combustion is exhaust soot. It is partially burned fuel. The soot causes backpressure, which triggers the regeneration. Now you’re having headaches. Excessive fuel consumption, lost time, and headaches are all possible. EGR valves and coolers, sensors, turbo actuators, and fuel injectors are just a few examples.

Excessive DPF Regeneration can only be solved by eliminating or drastically reducing diesel particulate matter (soot). You can achieve almost perfect combustion efficiency, and exhaust soot will drop to the point that DPF regenerations (or “regens”) would be rare. The solution is to eliminate most of the soot from the exhaust while simultaneously improving the fuel burn. DPF Remedy increases combustion efficiency, reduces soot, and “regens” by up to 90%

You will get better combustion, a faster and more efficient burn, and dramatic reductions in soot. DPF regeneration is less necessary if there’s less soot. DPF Remedy eliminates DPF problems by starting with the first tank. Many of our clients have noticed changes from daily regens to weekly and monthly. It happens quickly, and it is that powerful. It usually occurs with the first tank. Clean EGR valves, emissions sensors, injectors, and proper administration of DEF are all necessary for soot reduction.

Passive Regeneration is used in All Engines

All DPF systems have passive regeneration. Perkins engines can be passive or active, so no need to have a dynamic system.

Passive regeneration is an option if you look for a simple, invisible solution to the operator. Passive regeneration does not require additional lights or controls to increase the operator’s workload. The DPF can perform as intended because it’s a continuous process, and operators won’t need to worry about the machine’s maintenance with Perkins’ service-free system.

Passive regeneration is a method of ensuring reliable operation for various applications and duty cycles, meaning that the DPF system can be used on-site or in the field, and it will not cause any disruptions to the operator. It also ensures minimal downtime, which results in increased productivity.

What is Stopping Normal Regeneration from Happening?

The vehicle’s duty cycle is the biggest reason for insufficient DPF regeneration. If you want to complete a DPF regeneration, engines must operate at high temperatures and high RPM for extended periods. Your duty cycle will be similar to most trucks in real life. There will be wait times, many starts and stops, congested traffic with high idle times, bad conditions, long trips, multiple deliveries/stops, and a combination of all these situations

.DPF Remedy uses space-age fuel technology and chemistry to improve engine performance and combustion efficiency. It is not a 99c additive to lottery tickets or fuel shots at the fuel desk.

DPF Remedy has been approved by the EPA and is safe for all engines. This product is very cost-effective and will save you a lot of fuel. It also reduces repair costs. Your truck should be on the road and not in the workshop.

Use the correct oil and OEM-recommended Diesel Exhaust Fluid. There is no substitute for regular maintenance.

DPF Remedy uses space-age fuel technology and chemistry to improve engine performance and combustion efficiency. It is not a 99c additive to lottery tickets or fuel shots at the fuel desk.

Fault Code Lamps before Freightliner regen

1. The Malfunction Indicator Lamp/CheckEngine

Commonly, the malfunction indicator lamp is called the check engine light. This error lamp is usually based on engine-management software and indicates an engine malfunction.

Detroit Diesel stated that you can drive the truck until the end of the shift and that it is not an indicator that needs immediate attention.

2. The HEST Lamp

The HEST lamp has a high exhaust system temperature due to increased regen speed caused by low truck speeds or parked trucks. This lamp blinks when parked regen progresses, and the system temperature is not at its optimal.

This warning light only warns the operator about the hot exhaust system.

3. DPF Status Lamp

DPF lamp refers to the diesel particulate filter lamp. If it is stable, then parked regeneration may be required. You need to understand your DPF the status of your DPF light to determine if DPF regeneration is required for Freightliner.

DPF warning lights can be either solid or flashing, but they are generally not flashing. These two states signify two types of warnings. If the light flashes, you will need to start parked regeneration immediately.

Another option is to drive the car at highway speed to activate the regeneration of the filter. The diesel particulate filter exceeds system limits if the DPF lamp illuminates beside the check engine and turns off the engine light. You will need to do a parked regeneration.

It may be time to replace your filter system if your truck has traveled more than 500,000 miles or is over 10,000 hours.

Second method: Use a Scanner

A scanner/code reader is a quick and easy way to determine if your Freightliner’s DPF needs to be regenerated or if it is in good health. These scanners can check the health of your DPF, oil, and other important information. This scanner is an excellent option for Freightliner and light-duty cars to determine the health of your DPF, oil, and other components.

Third Method: The DPF Status Light is on Steadily

This light indicates that your engine might need refuelling, and it may take a while to start degrading. In such cases, you can perform passive or active regeneration on the truck (these processes are described below).

You would need to continue driving at highway speeds (on the highway) without interruption. It’s possible to do this for around 45 minutes, but make sure the light goes out.

Fourth Method: The DPF Status Light is Flashing

Flashing lights are alarming as they indicate that your DPF needs to be replaced urgently. If you ignore the DPF status light, this will occur, signifying that you need to perform parked regeneration as soon as possible. Below is a description of a parked regeneration.

Fifth Method: Check Engine With DPF Light Flashing

It is imperative to perform parked DPF regeneration immediately.

Attention: The DPF will degrade if it isn’t cleaned regularly. It will also shut down without warning at any time.

After Treatment Systems

If your truck has traveled 500,000 miles or 800,000 kilometers, and your dashboard lights up, it could be indicating that the DPF needs to be cleaned. You or a technician must remove the DPF filter to perform manual cleaning.

You will often need to frequently replace the DPF filter and the diesel oxidation catalyst (DOC). Be aware of DPF filter cleaning techniques and avoid the “bake-and-blow” method that uses compressed air to blow ash into the substrate.

You can use thermal baking to remove hydrocarbons that block filters. These methods are not the best cleaning methods and can cause damage to an after-treatment system.


Although the initial technology to control emissions was not the most reliable, modern models are much more fuel-efficient and easier to maintain.



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