Engine Power Output Low
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Symptom |
Possible Cause |
Action |
Reference |
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Engine Power Output Low |
Active DTC's or high counts of inactive DTC's |
Check for active and inactive DTC's. |
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Engine control module (ECM) calibration is malfunctioning |
Using Consult confirm ECM has the latest software revision. |
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Incorrect ECM calibration, incorrect fuel grade, or engine fan stuck on |
The following items should be verified before continuing the low power troubleshooting procedure. Using CONSULT, confirm ECM has the latest software revision. Verify the fuel grade is correct. Verify the engine fan is not locked ON, causing excessive engine parasitic load. |
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Leaking air intake system or charge-air cooler |
Inspect the air intake and exhaust systems for air leaks. Check all EGR plumbing, intake plumbing, charge-air cooler hoses, and exhaust plumbing for possible air leaks. |
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Leaks in the exhaust gas recirculation (EGR) plumbing or exhaust system |
Check for leaks in the EGR and exhaust system. Specifically look for leaks at connection tubing, V-band connections, turbocharger mounting gaskets, and EGR cooler plumbing connections. |
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Lubricating oil level is above specification |
Check the oil level. Adjust oil to the specified level. |
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Lubricating oil does not meet specifications for operating conditions |
Change the oil and oil filter. |
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Malfunctioning fuel injector(s) |
Perform CONSULT Cylinder Cut-out Test to determine if the misfire can be isolated to a single injector. Perform CONSULT High-Pressure Fuel injector return flow test. Replace the injector(s) as necessary. |
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Incorrect engine operating state |
Use CONSULT to monitor the engine state. |
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Plugged fuel filters |
Check for plugged or restricted fuel filters. |
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Malfunctioning lift pump |
Check the lift pump operation. |
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High fuel inlet restriction |
Perform the Fuel Inlet Restriction Test. |
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High air intake restriction |
Check the air filter to make sure it is not plugged. Check the air intake system for restriction. |
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Engine Power Output Low (continued) |
Fuel contaminated with Diesel Exhaust Fluid (DEF) |
Verify high quality fuel is being used and that no history of DEF in the fuel system. DEF in the fuel system can cause fuel system to become inoperative over time. |
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Stuck open exhaust gas recirculation (EGR) valve |
Use CONSULT to perform the Aftertreatment Diesel Particulate Filter Regeneration Test. Allow the stationary regeneration procedure to run a minimum of 5 minutes. Use CONSULT to monitor EGR VALVE POS and EGR VALVE POS CMD. Verify that both valves match each other during the DPF Regeneration Test. Troubleshoot any active DTCs if the values do not match. |
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Air in the fuel |
Check for air in the fuel system. |
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High exhaust restriction |
Check for exhaust restriction. |
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Worn or damaged turbocharger blades |
Inspect the turbocharger compressor and turbine blades for damage or wear. |
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Engine crankcase gases (blowby) excessive |
Check for excessive crankcase pressure. If the crankcase blowby is excessive, refer to Crankcase Gases (Blowby) Excessive symptom diagnosis. |
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High turbocharger compressor intake temperatures |
The compressor intake temperature should be within a few degrees of ambient outside temperature. If a temperature increase is detected between the air cleaner (ambient outside temperature) and the compressor intake temperature, investigate the cause of the temperature increase. |
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Malfunctioning accelerator pedal |
Check the percent accelerator pedal reading with CONSULT. Verify that it reads 100 percent with the accelerator pedal depressed and 0 percent when released. Replace the accelerator pedal, if necessary. |
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Engine Power Output Low (continued) |
Poor fuel quality or fuel additives |
Operate the engine with a known high quality fuel supply and determine if the performance symptoms are eliminated. Verify the customer is not using fuel additives that could cause low power complaints. |
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Excessive vehicle parasitics |
Check the vehicle for brakes dragging, transmission malfunction, and cooling fan operation cycle time. |
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Worn or damaged hydraulic lash adjusters |
Inspect hydraulic valve adjuster for excessive wear or damage. |