HOLLY, Mich., Feb. 04, 2026 (GLOBE NEWSWIRE) -- Diesel engines are known for their high torque and long-term reliability compared with gasoline engines, but they’re not immune to the occasional loss of power. Power loss may look like sluggish acceleration, struggling when towing or going uphill, stalling or going into “limp mode.” Warning lights will often illuminate. Fortunately, there are simple troubleshooting steps vehicle owners can take to figure out what might be wrong and how to address it.
“Many of the reasons diesel vehicles lose power are related to issues with fuel, air or electronics,” explains Clay Parks, vice president of development for leading additive manufacturer Rislone. “While minor computer glitches can sometimes be cleared up by simply turning off the engine, waiting 15 to 20 seconds and restarting, others take a little more effort to diagnose and repair.”
Fuel System Issues
Anything that interferes with a consistent supply of fuel reaching the engine can affect the power generated. Potential issues include clogged fuel filters, gelled or frozen fuel, and dirty or failing injectors.
Start by checking the owner’s manual to see if the vehicle is due for a fuel filter change. Most manufacturers recommend changing the fuel filter every 10,000–20,000 miles. Remember that many diesel vehicles have more than one fuel filter. Changing the fuel filter takes 30 to 60 minutes on average.
Diesel fuel may thicken in winter as cold temperatures cause paraffin wax in the fuel to clump up. Similarly, water in may condense in the fuel tank and mix with fuel. In freezing temperatures, that water can crystalize. In either case, the fuel may clog fuel lines and filters. To avoid this, choose high-quality winter-grade fuel from reputable stations and drain the engine’s water separator regularly. Also, consider installing a fuel system treatment to stabilize and condition the fuel to prevent it from gelling.
Also check the fuel pump. A weak pump may not be able to deliver enough fuel, especially at higher RPMs. Use a fuel pressure gauge to test that the pressure is within the manufacturer's specifications.
For diesels regularly driven for short periods of time at slow speeds, there may be a blockage in the diesel particulate filter (DPF). This is usually indicated by a DPF warning lamp or general “check engine” light. Using an OBD-II diagnostic code reader may show a P242F or related trouble code. OBD-II readers can be purchased for home use. Many auto parts stores also offer free in-store scans.
Cleaning a clogged DPF doesn’t have to be time-consuming or expensive thanks to recent advances in chemical technology. Just pour a bottle of Rislone DPF Clean® Diesel DPF, Exhaust & Emissions System Cleaner (part #4744) into the fuel tank and drive to unclog the DPF. Treat the fuel system with the same product every 5,000 miles to keep the diesel engine truck running at its best, extend DPF life, and reduce regeneration cycles.
Clear the Air
A diesel engine needs clean air to burn the fuel efficiently and a clear path for exhaust gases to exit. Anything that impedes air flow in or out can impact engine performance.
As with fuel, the easiest place to start is with the filters. A dirty or collapsed air filter restricts airflow, choking the engine. Keep in mind that a filter can be clogged not just by airborne particles, but also by leaves or even snow. Inspect the filter and remove any visible large debris. Replace the filter if it’s clogged or collapsed.
Vehicles that are usually driven at low speeds with light loads for short durations are also prone to developing white crystal deposits in their selective catalytic reduction (SCR) emissions systems. Letting these deposits build up in the diesel exhaust fluid (DEF) can put the vehicle into “limp mode.” Other signs of DEF crystal contamination include warning lights, decreased fuel efficiency and OBD codes P20EE, P20EF, P204F, P207F, P20E8 and P218F.
Crystal contamination can be eliminated by adding Rislone DEF Crystal Clean® Diesel DEF & SCR Emissions System Cleaner (part #4784) to the vehicle’s DEF/AdBlue® tank. Once the system is clean, use Rislone Diesel DEF Treatment (part #4780) with every DEF refill to keep crystals at bay and the system running smoothly.
Sensor and Electronic Control Issues
Today’s advanced diesel engines rely heavily on electronic sensors to smoothly adjust fuel and timing. But a failed sensor sending bad data may cause the engine control unit (ECU) computer to limit power to protect the engine.
Common culprits include the Mass Airflow (MAF) sensor, boost pressure sensor, and throttle position sensor. The check engine light often comes on when sensors fail. Use an OBD-II scanner to retrieve diagnostic trouble codes, which will point to the faulty sensor.
Learn more about protecting a diesel vehicle’s emissions system, avoiding costly repairs, and improving performance at Rislone.com/diesel-defense.
About Rislone
Rislone is one of the world’s original vehicle additive brands. Debuting in 1921, Rislone invented the “tune-up” and has helped maximize vehicle performance, fuel economy and durability ever since. All Rislone products are made in the USA and are available where vehicle parts and supplies are sold. Based in Holly, Michigan, Rislone is ISO 9001 certified.
*AdBlue® is a registered trademark of VDA Verband der Automobilindustrie e.V.
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Media Contact: Kristen Simpson Simpson Communications, LLC (216) 991-4297 kristen@simpsoncomm.com
