Komatsubulldozersmall ( - d39)

Komatsu DNH020-6L-21(S/N 60001-UP (D21P-6))

Maintenance schedule, common problems & OEM parts breakdown

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The Komatsu DNH020-6L-21 (S/N 60001-UP, D21P-6) is a mid-size crawler bulldozer designed for construction and earthmoving applications. It falls within the 8 to 108 tonne operating weight range of Komatsu's bulldozer lineup. The machine is equipped with a Komatsu 4D94LE-2 engine delivering 29.5 kW (40 HP) at 2450 rpm. Production years for this specific serial range are not documented in the available sources. The DNH020-6L-21 is part of the DNH020 series, which includes variants such as the DNH020-6L-20 and DNH020_6K_1C. Configurations offered for the DNH020 series include standard dozer setups with various blade and ripper options, though specific configuration details for the DNH020-6L-21 are not documented.

Across the DNH020 series, Komatsu introduced Tier 4 Final compliant engines and integrated KOMTRAX telematics for remote monitoring of hours, fuel consumption, and fault codes. The DNH020-6L-21 represents a generation with specific hydraulic and powertrain tuning compared to earlier models. In the used and parts market, this machine matters due to its compact size suitable for confined jobsites and the availability of Komatsu Genuine Lubricants and KOWA fluid analysis support. The machine's reliability is supported by Komatsu CARE programs for eligible units, which include factory-scheduled maintenance and KDPF exchanges. Used units are valued for their durability and the extensive network of aftermarket parts available for the D21P-6 platform.

Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.

Komatsu DNH020-6L-21(S/N 60001-UP (D21P-6)) specifications

Engine

ModelKomatsu 4D94LE-2
Net Power29.5 kW (40 HP) @ 2450 rpm

Weights

Operating WeightNot documented for this exact serial range — verify with your dealer

Dimensions

Transport DimensionsNot documented for this exact serial range — verify with your dealer
Track GaugeNot documented for this exact serial range — verify with your dealer
Shoe WidthsNot documented for this exact serial range — verify with your dealer
Ground ClearanceNot documented for this exact serial range — verify with your dealer

Performance

Travel Speeds (F/R)Not documented for this exact serial range — verify with your dealer
Drawbar PullNot documented for this exact serial range — verify with your dealer
GradeabilityNot documented for this exact serial range — verify with your dealer
Ground PressureNot documented for this exact serial range — verify with your dealer

Blades

Blade CapacitiesNot documented for this exact serial range — verify with your dealer

Service Capacities

Hydraulic Tank21 ltr
FuelNot documented for this exact serial range — verify with your dealer
Engine OilNot documented for this exact serial range — verify with your dealer
CoolingNot documented for this exact serial range — verify with your dealer

Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.

Komatsu DNH020-6L-21(S/N 60001-UP (D21P-6)) maintenance schedule

Service intervalTasks
Every 10 h
  • Check engine oil level and condition.
  • Check hydraulic fluid level at sight glass.
  • Check coolant level and ensure cap is secure.
  • Drain water from fuel separator.
  • Check DEF level.
  • Check air filter restriction indicator.
Every 250 h
  • Change engine oil and filter.
  • Grease all points including blade, ripper, and push arms.
  • Check fluid levels.
  • Check air filter outer element.
  • Inspect belts and hoses.
  • Perform visual walk-around inspection.
Every 500 h
  • Replace fuel filter.
  • Replace hydraulic return filter.
  • Test battery and alternator.
  • Test coolant SCA.
  • Collect KOWA oil sample.
  • Perform detailed undercarriage inspection.
Every 1,000 h
  • Collect hydraulic oil sample.
  • Change final drive oil.
  • Inspect turbocharger.
  • Take wear measurements.
  • Check valve adjustment.
  • Perform structural inspection.
Every 2,000 h
  • Change hydraulic oil.
  • Flush and replace coolant.
  • Service transmission.
  • Perform comprehensive component evaluation.
  • Check KDPF.
  • Check SCR system.

Servicing the DNH020-6L-21(S/N 60001-UP (D21P-6)) beyond the schedule

Predictive Maintenance & Fluid Analysis

Utilize KOWA fluid analysis at every 500-hour interval to monitor engine oil wear metals, hydraulic fluid particle count, and coolant pH levels. The Komatsu 4D94LE-2 engine requires specific diesel engine oil meeting Komatsu Engineering Standards. Check the air filter restriction indicator daily and replace the outer element at 1000 hours or when indicated. Monitor DEF levels daily to ensure Tier 4 Final compliance. Use KOMTRAX telematics to track load frequency and fault codes for proactive service scheduling.

Corrective & Common Repairs

Address hydraulic hose leaks and cracks during daily walk-around inspections. Replace the fuel filter and hydraulic return filter at 500-hour intervals to prevent contamination of the hydraulic system. Inspect the final drive oil for water ingress or metal particles at 1000 hours. Check the turbocharger for wear and boost leaks. Ensure all grease points on the blade, ripper, and push arms are lubricated to prevent premature wear of pins and bushings. Verify battery terminal tightness and alternator output at 500 hours.

Overhaul & Rebuild Points

Plan for major component evaluation at 2000-hour intervals, including hydraulic oil changes and coolant flushing. Inspect the undercarriage for wear on track shoes, rollers, and sprockets at 500-hour intervals. Check the structural integrity of the boom and stick welds at 1000 hours. Monitor the swing machinery oil level and condition. Replace worn belts and hoses as needed. Consider KDPF exchange at 4500 hours if equipped. Perform comprehensive brake system inspection and pad measurement at 2000 hours.

Seasonal & Environment Servicing

In cold climates, check coolant concentration and SCA levels to prevent freezing. Ensure the radiator and oil cooler fins are clear of debris to maintain proper operating temperatures. In dusty environments, inspect the air filter more frequently and replace the outer element as needed. Check the fuel water separator daily to prevent water contamination. Monitor hydraulic fluid viscosity changes in extreme temperatures. Ensure the DEF system is protected from freezing and contamination. Inspect the cooling system for leaks and proper cap seal integrity.

DNH020-6L-21(S/N 60001-UP (D21P-6)) common service parts

Part numberPart
103-60-23240Cartridge,Hydraulic Oil FilterCheck fitment →
113-60-43320Cartridge,Hydraulic Oil Filter (D31s)Check fitment →
113-60-43321Cartridge,Hydraulic Oil Filter (D31s)Check fitment →
07002-03334O-Ring, At Transmission FilterCheck fitment →

Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.

DNH020-6L-21(S/N 60001-UP (D21P-6)) fault codes & troubleshooting

CodeMeaningLikely causeWhat to do
CA115Engine crankshaft speed sensor failureBroken sensor, wiring issue, or connector corrosionReplace the speed sensor and verify voltage at the pin connector
CA441Battery voltage too lowAlternator failure, battery degradation, or loose connectionsReplace the alternator or battery; check the voltage regulator
CA442Battery voltage too highFaulty voltage regulator or alternator overchargingReplace the alternator or battery; check the voltage regulator
AA10NXAir cleaner cloggingDirty or blocked air filter elementReplace the air filter
CA122Intake air pressure high voltageFaulty intake pressure sensor or restricted airflowVerify the intake pressure sensor and wiring
CA123Intake air pressure low voltageSensor short circuit or significant airflow restrictionCheck for a sensor short or an airflow restriction
CA451Common rail pressure sensor feedback value too highMalfunction in the rail sensor or actual overpressure conditionDiagnose the fuel rail pressure sensor or pump lines
CA559Common rail pressure too lowFuel pump regulator (IMV/PCV) malfunction or leakEvaluate fuel pump regulator (IMV/PCV)
CA2311IMV solenoid valve failureFaulty IMV solenoid or wire harness issueReplace the IMV solenoid or inspect the wire harness
B@BCNSEngine coolant overheatingRadiator blockage, fan belt failure, or low coolant levelCheck radiator fins, fan belt, and coolant level

Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.

DNH020-6L-21(S/N 60001-UP (D21P-6)) attachments & work tools

Blades

The DNH020-6L-21 (D21P-6) series is a mid-size dozer compatible with standard, semi-universal, and universal blade types, as well as VPAT configurations. Factory specifications for this class typically list blade widths ranging from approximately 3.0 to 3.6 meters (9.8 to 11.8 feet) and capacities between 2.0 and 3.0 cubic meters (2.6 to 3.9 cubic yards), varying by specific configuration and series.

Rippers

This class of bulldozer supports both multi-shank and single-shank ripper options for soil breaking and site preparation. Multi-shank rippers are standard for this weight class, with shank counts and tip weights varying by configuration, typically ranging from 3 to 5 shanks with individual tip weights between 10 and 20 kilograms (22 to 44 pounds).

Winches

Towing winch options for the DNH020-6L-21 series generally fall into the 10 to 15 tonne (22,000 to 33,000 lbs) class, suitable for recovery and heavy pulling tasks. These winches are typically mounted to the rear drawbar or frame, with cable capacities ranging from 100 to 150 meters (328 to 492 feet).

Drawbars/Counterweights

Rear drawbars for the DNH020-6L-21 series are designed to accept standard hitch pins and winch mounts, with mounting points spaced to accommodate various tool widths. Counterweight options are available to balance front-mounted blades or rippers, typically adding between 1,000 and 2,000 kilograms (2,200 to 4,400 lbs) to the rear structure.

Cab/ROPS Guarding

Forestry and waste configurations for the DNH020-6L-21 series include enhanced ROPS/FOPS guarding, heavy-duty screen mesh, and protective grilles for the radiator and hydraulic lines. These options are designed to meet ISO 3449 and ISO 3471 standards for operator protection against falling objects and flying debris.

Hydraulic Arrangement

The DNH020-6L-21 series utilizes a closed-center hydraulic system with dedicated circuits for front blade and rear ripper tools, allowing for simultaneous operation. Front tool hydraulics are typically routed through the A-frame with quick-disconnect couplers, while rear ripper hydraulics connect directly to the rear frame ports, with flow rates varying by configuration.

All DNH020-6L-21(S/N 60001-UP (D21P-6)) assemblies by section

Every catalogued assembly group for the Komatsu DNH020-6L-21(S/N 60001-UP (D21P-6)). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Guard
Komatsu : Dnh020-6l-21(S/N 60001-Up (D21p-6)) : Guard : Rear Cover And Hydraulic Tank (For 3-Point Hitch)(#60001-64227)
01***20Bolt,(With Auto Emergency Steering)3
01***20Bolt,(For Quick Shift) (Mitsubishi)8
01***25Bolt,(For Canvas Canopy?Head Guard)6
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Komatsu : Dnh020-6l-21(S/N 60001-Up (D21p-6)) : Guard : Rear Cover And Hydraulic Tank (For 3-Point Hitch)(#64228-)
01***20Bolt,(With Auto Emergency Steering)3
01***20Bolt,(For Quick Shift) (Mitsubishi)8
01***40Bolt,(With Service Valve R.H.)4
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Work Equipment
Komatsu : Dnh020-6l-21(S/N 60001-Up (D21p-6)) : Work Equipment : 3-Point Hitch (1/2)
01***45Bolt, Mount Center Hinge Retainer (Lower)4
01***20Bolt,(For Quick Shift) (Mitsubishi)6
01***40Bolt (Op)8
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Komatsu : Dnh020-6l-21(S/N 60001-Up (D21p-6)) : Work Equipment : 3-Point Hitch (2/2)
01***16Bolt, Mount Washer Tank To Bracket, Bolt2
01***25Bolt,Without Revolution Sensor6
01***25Bolt,(For Canvas Canopy?Head Guard)4
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Komatsu : Dnh020-6l-21(S/N 60001-Up (D21p-6)) : Work Equipment : 3-Point Hitch Cylinder
01***25Bolt,(For Canvas Canopy?Head Guard)2
01***32Washer,(With Auto Emergency Steering)2
07***70O-Ring,(For Intake Air Cover)1
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Komatsu : Dnh020-6l-21(S/N 60001-Up (D21p-6)) : Work Equipment : Swing Drawber (For 3-Point Hitch)
01***35Bolt,R.H. Outside And L.H. Inside8
01***40Bolt,R.H. Outside And L.H. Inside, Bolt4
01***42Washer,Spring (For Pedal Steering), Washer-Spring12
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Work Equipment Control System
Komatsu : Dnh020-6l-21(S/N 60001-Up (D21p-6)) : Work Equipment Control System : Hydraulic Piping (3-Point Hitch Cylinder Line)(For 3-Point Hitch)
01***18Bolt1
01***20Bolt,(With Auto Emergency Steering)1
01***20Bolt,(For Quick Shift) (Mitsubishi)2
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Komatsu : Dnh020-6l-21(S/N 60001-Up (D21p-6)) : Work Equipment Control System : Hydraulic Tank And Filter (For 3-Point Hitch)
01***25Bolt,Without Revolution Sensor7
01***25Bolt,(For Canvas Canopy?Head Guard)3
01***25Washer,Spring?For Additional Rear Lam7
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Komatsu : Dnh020-6l-21(S/N 60001-Up (D21p-6)) : Work Equipment Control System : Work Equipment Control Lever (1/2) (For 3-Point Hitch)
01***16Bolt (With Air Heater & Conditioner)2
01***20Bolt,(With Auto Emergency Steering)8
01***30Bolt,(For Mechanical Governor)1
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Komatsu : Dnh020-6l-21(S/N 60001-Up (D21p-6)) : Work Equipment Control System : Work Equipment Control Lever (2/2) (For 3-Point Hitch)
01***05Nut,L.H. Thread (D31s)1
01***05Nut,L.H. (For Trimming Dozer)1
01***06Nut,(With Back-Up Alarm) (Op), Nut; Was 01580-108061
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Komatsu : Dnh020-6l-21(S/N 60001-Up (D21p-6)) : Work Equipment Control System : Work Equipment Valve (1/2) (For 3-Point Hitch)
01***16Bolt (Op)4
01***25Bolt, Seal Cover Mounting4
01***30Bolt4
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Komatsu : Dnh020-6l-21(S/N 60001-Up (D21p-6)) : Work Equipment Control System : Work Equipment Valve (2/2) (For 3-Point Hitch)
01***08Nut (Op)1
07***11O-Ring (Kit)1
07***15O-Ring,(Without Boom Kickout)1
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Frequently asked questions

What engine does the Komatsu DNH020-6L-21 use?

The Komatsu DNH020-6L-21 uses a Komatsu 4D94LE-2 engine with 29.5 kW (40 HP) at 2450 rpm.

What is the operating weight of the Komatsu DNH020-6L-21?

The operating weight varies by configuration/series. Komatsu bulldozers range from 8 to 108 tonnes, but the specific weight for the DNH020-6L-21 is not documented in the available sources.

What replaced the Komatsu DNH020-6L-21?

The specific successor model to the DNH020-6L-21 is not documented in the available sources. The DNH020 series includes variants such as the DNH020-6L-20 and DNH020_6K_1C.

What DNH020-6L-21(S/N 60001-UP (D21P-6)) owners discuss

What are the known powertrain and hydraulic behaviors for the Komatsu DNH020-6L-21(S/N 60001-UP (D21P-6))?
The machine utilizes a Hystat transmission system. Community consensus indicates that hydraulic weakness when hot, rather than cold, often points to internal leakage in the pump, main control valve, or motors as viscosity decreases. Slow travel or 'walking fatigue' is a common symptom of worn components or low fluid levels. If all hydraulic functions become slow simultaneously, the issue typically lies in the shared hydraulic supply, pump control, or engine performance rather than individual cylinders. The line is noted for smooth operation and fuel efficiency; however, complete machine wear-out is a known lifecycle pattern where pump failure may precede engine failure, impacting resale value. Variations in hydraulic pressure and control strategies exist between Dash 5 and Dash 6 generations; verify specific pressures for the D21P-6 series with your dealer.
What undercarriage or wear patterns are typical for this machine type?
Undercarriage wear is accelerated by mud or debris packed into the track frames and rollers. Track tension must be checked regularly, as repeated loosening often indicates issues with the tensioner or worn components. Bushings, bearings, and track pads are subject to significant wear; worn bushings can lead to noise and vibration, while worn bearings may cause premature track failure. The unique undercarriage design is intended to reduce ground pressure and improve cost-efficiency, but mechanical resistance from binding tracks or improper tension can skew hydraulic diagnosis. Always inspect the track-chain condition and roller state before attributing travel issues to hydraulic motors.
What are the engine quirks per series for the Komatsu DNH020-6L-21(S/N 60001-UP (D21P-6))?
The D21P-6 series is associated with Yanmar engines in community discussions, noted for reliability and longevity even at high hour counts. Common engine issues include loss of power under load, increased fuel usage, and overheating. These symptoms often signal airflow restriction, injector wear, or failing fuel delivery components. A machine may idle normally but lose power when combining heavy hydraulic loads, indicating the engine cannot produce expected power or the hydraulic system is placing excessive load. Cooling package blockage between heat exchangers is a frequent cause of overheating during heavy work. Engine derating may occur due to aftertreatment or sensor faults.
What are the common electrical and sensor issues?
Komatsu machines rely heavily on electronic control systems, where a single faulty sensor or unstable power supply can trigger multiple warning signals. Owners report intermittent starting, dashboard failure, or random shutdowns. Common electrical diagnostics involve checking battery state of charge, terminal condition, and engine/chassis grounds. Voltage collapse under starter load is a critical indicator of battery health. Faulty sensors can cause the machine to derate or shut down unexpectedly. Monitor panels may require repair if lights illuminate but data is incorrect.
What should be checked when buying a used DNH020-6L-21(S/N 60001-UP (D21P-6))?
Inspect the steering clutch and brake band condition, as the Dash 5 generation had issues with inner seals and lack of re-lubrication provisions leading to stickiness or freezing. Check for gray market parts availability if the machine is not a standard regional spec. Verify the exact serial-prefix specification sheet, as configurations, counterweights, and track shoe sizes affect weight and performance. Test hydraulic performance both cold and hot to identify internal leakage. Check for black smoke from the exhaust, which may indicate fuel system issues. Ensure the cooling package is clean between heat exchangers. Verify the condition of the main safety valve, as grinding or repair may be needed for smooth operation.
How do you diagnose slow travel or pulling to one side?
Determine if the issue affects one track or both. If both tracks are slow, check the hydraulic supply, pilot control, travel control input, and safety interlocks. If only one track is slow, focus on that travel motor, final drive, and travel control valve circuit. Check mechanical conditions first, including track tension, mud packing, and roller condition. Test the symptom in both forward and reverse; if the same side remains weak in both directions, it points to a hydraulic or final-drive issue rather than mechanical binding. Compare travel speeds on both sides to identify discrepancies.
What are the common hydraulic system concerns for used Komatsu dozers?
Hydraulic leaks, stuck components, and inadequate fluid levels are common issues. Leaks in lines or cylinders can result from worn seals or improper installation. Over-pressurized systems can also cause seal failure. If the machine works cold but becomes weak when hot, suspect hydraulic pump wear, main control valve leakage, or incorrect/degraded oil. The main safety valve is critical for smooth operation; slow heating or poor performance may require grinding and repair. Regular inspection of the hydraulic system and fluid condition is essential. Flush the system if contamination is suspected.

Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.

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