P2459 Code 6.7 Cummins- Causes and Solutions

The diagnostic trouble code P2459 indicates a problem with the diesel particulate filter(DPF) regeneration frequency bank 1. The filter does self-cleaning in a process called regeneration, where it converts soot to ash. If the vehicle doesn’t warm up to the required temperatures, the process fails to complete.

The code P2459 can have several causes, including a fault in the fuel or the air handling system. Among the symptoms include reduced vehicle performance, warning light illumination, and vehicles regularly getting into limp mode. The issues are solved by repairing or replacing the failing part.

Let’s dive in and learn how I have dealt with this issue-

What Causes P2459 Code on Vehicles With 6.7 Cummins

Code P22459



Failing DPF filterDrive for longer distances to allow the engine to reach the optimum temperature
Air handling system and sensor failureClean the air sensor with specific cleaners. Replace or clean the air filter to clear dirt.
Blocked EGR ValveSpray with a cleaner to clean the carbon deposits clogging it
Faulty fuel systemRepair the fuel system or replace them.
Turbocharger failureFix leakages into the DPF

The causes behind the P2459 are discussed below with the possible solutions.

1. Failing DPF Filter

The diesel particulate filter burns the soot from the exhaust gas and turns it into ash. However, the vehicle must reach an operating temperature between 550 – 650°C (1022 – 1202°F)

Temperatures lower than that can encourage the accumulation of soot on the DPF. With the filter clogged, the sensors on the after-treatment system will detect an issue and trigger the code P2459.


  • Specialists advise drivers not to drive at low revs or for short distances to prevent diesel particulate filters from failing.
  • Even though not daily, regularly drive the vehicle for long distances at high RPMs.

2.  Air handling System and Sensor Failure

The air handling system provides the air needed to mix with fuel for after-treatment regeneration. However, if the system is exposed to dirt and exhaust fumes, it can be damaged or its sensor clogged.

The air filter and sensor malfunction can result in a failed combustion due to an imbalanced air-to-fuel ratio. In turn, the after-treatment system fails, resulting in the diagnostic trouble code.


  • The air filter system repair includes cleaning the clogged part of the dust, and exhaust fumes, which can solve the issue
  • Replace the air filter with a new one and clean the air sensor using its cleaners

3. Blocked EGR Valve

The exhaust recirculation system, EGR, recirculates unburnt exhaust to reduce NOx emissions. The valve that controls the exhaust circulating back to the engine can sometimes get clogged or blocked.

The circulation seizes, and unburnt exhaust gasses are forced down the exhaust system. They can block and damage the DPF, resulting in the code P2459.


  • EGR valves should be serviced once a year or after 5000 km or 3100 miles to minimize the chances of blockages. Servicing involves spraying the EGR valve to clean the carbon deposits.

4. Fuel System Failure

The fuel system provides fuel to the Doser valve for combustion in the after-treatment system. If the system fails, the 7th injector can’t produce gas used for passive or active regeneration.

The diesel particulate filter soon after gets clogged, and the backpressure gauge triggers the code.


Contaminated fuel or blockage in the system can cause system failure and must be repaired or replaced.

5. Turbocharger Failure

Among the reasons, people like the Cummins 6.7L is its powerful turbocharger, which produces more power in a given displacement. However, oil contamination or leakage can affect the DPF due to increased soot. With the soot overwhelming the after-treatment system, the sensor sends the P2459 code.


Most turbocharger problems are related to oil contamination or leakages. Change the oil regularly and use quality diesel fuel for your Cummins 6.7L engine.

What Are the Symptoms of The Issues Causing Code P2459?

Limp Mode Symbol In Car

Before the diagnostic trouble code, various symptoms can signify the problems. They include-

1. Warning Lights

Warning lights like the check engine light can be a symptom of the DPF. It can mean the engine is failing or a possible problem with the fuel system. A flashing DPF light requires an immediately forced regeneration. (1)

2. Poor Fuel Economy

With the problems worsening, much fuel is used by the Doser injector to increase the temperature in the after-treatment. The vehicle uses more gas to clean the exhaust rather than power the vehicle.

3. Vehicle Gets to Limp Mode

The failing DPF means most exhaust fumes are left untreated and stuck in the after-treatment system. The exhaust can cause problems with the engine forcing the car into limp mode.

4. Reduced Engine Performance

Since the diagnostic trouble code affects the exhaust system, it can pressure the engine resulting in a misfire. A misfire causes poor performance because the engine only produces little power. (2)

The symptoms can signify other problems and require a test to verify. The first way to clear the doubts is by driving for about 30 minutes on high engine revs to trigger a passive regeneration. You can also use a diagnostic tool to force a regeneration or get a mechanic to do it for you.

Read More-

  1. Causes and Solution of P2262 Code In a 6.7 Cummins
  2. What is the Meaning of the P226C Code on 6.7 Cummins


The answers are well-researched to clear any of your remaining doubts-

Q: How Much Can Diagnosing Code P2459 Cost?

Diagnosing the trouble code is charged hourly in most repair shops. Depending on the repair shop, the cost can be between $70 and $150.

Q: How Long does it take to fix code P2459?

The process of DPF static regeneration takes between 30 minutes to one hour to complete. During the process, the engine runs on the necessary rpm to heat the after-treatment system.

Bottom Line

Despite the 6.7 Cummins engine being powerful, the parts used for emission regulations often cause problems. Among the problems is the diesel particulate filter, which can cause the code P2459. The filter develops issues when it’s unable to burn soot to ash.

Driving at low rpm or in city centers where you regularly stop, can cause the DPF to fail. In the article, I discussed the possible solutions to improve the particulate filter performance. Also, perform checks after observing the symptoms above to be certain of the problems.


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