Komatsubulldozersmall ( - d39)

Komatsu DNH020_6L_AC(S/N 60001-UP (D20A-6))

Maintenance schedule, common problems & OEM parts breakdown

Search live DNH020_6L_AC(S/N 60001-UP (D20A-6)) parts

The Komatsu DNH020-6L-AC (S/N 60001-UP, D20A-6) is a small crawler bulldozer designed for light to medium earthmoving, grading, and site development. It is powered by the D20A-6 engine series. Operating weights for this class of dozer typically range from 8 to 108 tonnes across the broader Komatsu lineup, with specific weights for the DNH020 series varying by configuration and attachment package. Production years for the 6-series generation span the late 1990s through the early 2000s. This model sits within the small dozer category, preceding the D21 series and succeeded by later Tier-compliant generations. Configurations offered include standard and low-ground-pressure (LGP) variants, with options for different blade capacities and undercarriage setups to suit specific ground conditions.

Across the 6-series generation, Komatsu refined the DNH020 platform to improve fuel efficiency and operator comfort while maintaining the durability expected in the small dozer class. The D20A-6 engine provided a balance of power and emissions compliance for its era. In the used and parts market, the DNH020-6L-AC remains relevant due to its widespread use in municipal, agricultural, and light construction applications. Its modular design and commonality with other D-series components make it a cost-effective option for fleet maintenance. The machine's continued presence in the secondary market is driven by its reliability in tight spaces and the availability of aftermarket support for high-wear items like undercarriage components and engine parts.

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_AC(S/N 60001-UP (D20A-6)) specifications

Engine

Engine ModelD20A-6
Emissions TierTier 2

Weights

Operating Weight41,700 kg (91,933 lb)

Dimensions

Transport Height3.5 m (11 ft 6 in)
Transport Width3.2 m (10 ft 6 in)
Transport Length7.93 m (26 ft 0 in)
Track Gauge1.6 m (5 ft 3 in)
Ground Clearance0.41 m (1 ft 4 in)

Performance

Travel Speed (Forward)3.4 km/h (2.1 mph)
Travel Speed (Reverse)3.4 km/h (2.1 mph)
Gradeability30 degrees
Ground Pressure0.07 MPa (10.2 psi)

Blades

Blade TypeSemi-U (SU)
Blade Capacity9.4 m³ (12.3 cu yd)
Blade Width3.2 m (10 ft 6 in)

Service Capacities

Fuel Tank Capacity450 L (119 gal)
Hydraulic System Capacity180 L (47.6 gal)
Engine Oil Capacity22 L (5.8 gal)
Cooling System Capacity35 L (9.2 gal)

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

Komatsu DNH020_6L_AC(S/N 60001-UP (D20A-6)) maintenance schedule

Service intervalTasks
Every 10 h
  • Check engine oil level and condition.
  • Check hydraulic fluid level via sight glass.
  • Check coolant level and ensure cap is secure.
  • Drain water from fuel separator.
  • Check DEF level on Tier 4 machines.
  • Inspect air filter restriction indicator.
  • Check track tension and shoe/pad condition.
  • Inspect hydraulic hoses for cracks or leaks.
  • Check pins, bushings, and attachment points.
  • Clear debris from radiator and oil cooler fins.
  • Check for fluid leaks under the machine.
  • Verify ROPS/FOPS integrity and seat belt.
  • Test horn, backup alarm, and lights.
  • Ensure emergency shutoff is accessible.
  • Start engine and verify gauges and KOMTRAX display.
  • Test all controls for smooth response.
  • Check service and parking brakes.
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.
  • Perform battery service and load test.
  • Test coolant SCA concentration.
  • Collect KOWA oil sample.
  • Perform detailed undercarriage visual inspection.
Every 1,000 h
  • Collect hydraulic oil sample.
  • Change final drive oil on both sides.
  • Inspect turbocharger.
  • Measure wear on components.
  • 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 (if equipped).
  • Torque ROPS bolts.
  • Check cutting edge and end bit bolt torque.
  • Inspect and replace worn belts, hoses, and clamps.

Servicing the DNH020_6L_AC(S/N 60001-UP (D20A-6)) beyond the schedule

Predictive Maintenance & Fluid Analysis

Utilize KOWA fluid analysis at every 500-hour interval to monitor engine wear metals, hydraulic contamination, and coolant condition. Check the air filter restriction indicator daily and inspect the outer element at 250-hour intervals. Monitor hydraulic oil particle count and viscosity during the 1000-hour service. Use KOMTRAX telematics to track load frequency and fault codes, allowing for proactive scheduling of filter replacements and fluid changes before failure occurs.

Corrective & Common Repairs

Address common DNH020-6L-AC issues by inspecting hydraulic hoses for cracks during daily checks and replacing them at the 2000-hour interval if wear is evident. Check track tension and undercarriage wear monthly to prevent premature sprocket and roller failure. Inspect the D20A-6 engine for oil leaks around gaskets and seals. Replace the fuel water separator daily to protect the injection system. Verify belt and hose integrity at 250-hour intervals to avoid sudden breakdowns.

Overhaul & Rebuild Points

Plan major overhauls for the D20A-6 engine and final drives around the 4000-6000 hour mark, depending on load conditions. Inspect the turbocharger and valve adjustments at 1000-hour intervals to identify early signs of wear. Evaluate the hydraulic pump and cylinder seals during the 2000-hour comprehensive service. Monitor undercarriage component wear measurements at 1000-hour intervals to determine the optimal time for track group replacement and prevent structural damage to the chassis.

Seasonal & Environment Servicing

In cold climates, check coolant concentration and SCA levels at 500-hour intervals to prevent freezing and corrosion. Use Komatsu Genuine Lubricants with appropriate viscosity for low-temperature starts. In dusty environments, clean the radiator and oil cooler fins daily and check the air filter more frequently. Inspect the DEF system and tank for contamination in all operating conditions. Ensure proper track tension adjustment for muddy or rocky terrain to maintain traction and reduce undercarriage stress.

DNH020_6L_AC(S/N 60001-UP (D20A-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_AC(S/N 60001-UP (D20A-6)) fault codes & troubleshooting

CodeMeaningLikely causeWhat to do
CA115Engine crankshaft speed sensor and backup speed sensor failureFaulty speed sensor, broken wiring harness, or corroded connector at the sensor pinReplace the speed sensor and verify voltage at the pin connector
CA451Common rail pressure sensor feedback value too highMalfunctioning rail pressure sensor or actual overpressure condition in the fuel systemDiagnose the fuel rail pressure sensor and check pump lines
CA122Intake air pressure sensor feedback voltage too highFaulty intake pressure sensor or wiring issueVerify the intake pressure sensor and wiring integrity
CA123Intake air pressure sensor feedback voltage too lowSensor short circuit or airflow restriction in the intake systemCheck for a sensor short or inspect for airflow restrictions
CA441Battery voltage too lowWeak battery, failing alternator, or loose connectionsReplace the alternator or battery and check the voltage regulator
CA442Battery voltage too highFaulty voltage regulator or alternator overchargingReplace the alternator or battery and check the voltage regulator
CA234Engine overspeedThrottle calibration error, engine load cycle issue, or operator misuseVerify throttle calibration and engine load cycle settings
AA10NXAir cleaner cloggingDirty or blocked air filter elementReplace the air filter element
B@BCNSEngine coolant overheatingLow coolant level, blocked radiator fins, or fan belt failureCheck radiator fins, fan belt, and coolant level
B@HANSHydraulic oil overheatingContaminated hydraulic oil, clogged filter, or cooler fan malfunctionChange hydraulic filter and oil; check cooler fan operation

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

DNH020_6L_AC(S/N 60001-UP (D20A-6)) attachments & work tools

Blades

The DNH020-6L-AC (D20A-6) configuration utilizes a D20A-6 engine platform. Factory specifications for this series typically include Straight (S), Semi-U (SU), and Angle (A) blade types. VPAT (Variable Position Angle Tilt) blade availability varies by configuration and series. Typical widths and capacities for this class range from 3.0 to 4.0 meters (9.8 to 13.1 feet) with capacities between 2.0 and 3.0 cubic meters (2.6 to 3.9 cubic yards). Specific dimensions vary by configuration/series.

Rippers

Multi-shank rippers are standard for this class, with single-shank options available for specific heavy-duty configurations. Ripper weights for this class typically range from 1,500 to 2,500 kilograms (3,300 to 5,500 pounds). Exact weight and shank count vary by configuration/series.

Winches

Towing winch options are available for this class, typically rated for 50 to 100 kilonewtons (11,200 to 22,500 pounds) of pull. Winch class and mounting configuration vary by configuration/series.

Drawbars/Counterweights

Drawbar and counterweight options are available to enhance traction and stability. Counterweight weights typically range from 1,000 to 3,000 kilograms (2,200 to 6,600 pounds). Specific configurations vary by configuration/series.

Cab/ROPS Guarding

Forestry and waste configuration guarding options include FOPS/ROPS certified cabs with enhanced screen protection and undercarriage guards. Specific guarding packages vary by configuration/series.

Hydraulic Arrangement

Front and rear tool hydraulic arrangements utilize standard Komatsu high-pressure circuits with quick-connect couplers. Hydraulic flow rates and pressures vary by configuration/series.

All DNH020_6L_AC(S/N 60001-UP (D20A-6)) assemblies by section

Every catalogued assembly group for the Komatsu DNH020_6L_AC(S/N 60001-UP (D20A-6)). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Guard
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-6)) : Guard : Rear Cover And Hydraulic Tank (For 3-Point Hitch)(#60001-63964)
01***20Bolt,(With Auto Emergency Steering)3
01***20Bolt,(For Quick Shift) (Mitsubishi)8
01***25Bolt,(For Canvas Canopy?Head Guard)6
See all parts with full part numbers in Heavy Parts AI →
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-6)) : Guard : Rear Cover And Hydraulic Tank (For 3-Point Hitch)(#63965-)
01***20Bolt,(With Auto Emergency Steering)3
01***20Bolt,(For Quick Shift) (Mitsubishi)8
01***40Bolt,(With Service Valve R.H.)4
See all parts with full part numbers in Heavy Parts AI →
Work Equipment
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-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
See all parts with full part numbers in Heavy Parts AI →
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-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
See all parts with full part numbers in Heavy Parts AI →
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-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
See all parts with full part numbers in Heavy Parts AI →
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-6)) : Work Equipment : Swing Drawbar (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
See all parts with full part numbers in Heavy Parts AI →
Work Equipment Control System
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-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
See all parts with full part numbers in Heavy Parts AI →
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-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
See all parts with full part numbers in Heavy Parts AI →
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-6)) : Work Equipment Control System : P.T.O. Control Lever (For 3-Point Hitch)
01***25Bolt,(Sandy? Dusty Terrain Spec.)2
01***16Bolt, Battery To Frame Ground Wire Attaching2
01***30Bolt,(For Quick Shift) (Mitsubishi)2
See all parts with full part numbers in Heavy Parts AI →
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-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
See all parts with full part numbers in Heavy Parts AI →
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-6)) : Work Equipment Control System : Work Equipment Control Lever (2/2) (For 3-Point Hitch)
01***05Nut,L.H. Thread (D31s)2
01***05Nut,L.H. (For Trimming Dozer)2
01***06Nut,(With Back-Up Alarm) (Op), Nut; Was 01580-108062
See all parts with full part numbers in Heavy Parts AI →
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-6)) : Work Equipment Control System : Work Equipment Valve (1/3) (For 3-Point Hitch)
01***16Bolt (Op)4
01***25Bolt, Seal Cover Mounting2
01***30Bolt2
See all parts with full part numbers in Heavy Parts AI →
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-6)) : Work Equipment Control System : Work Equipment Valve (2/3) (For 3-Point Hitch)
01***16Bolt (Op)4
01***25Bolt, Seal Cover Mounting2
01***30Bolt2
See all parts with full part numbers in Heavy Parts AI →
Komatsu : Dnh020_6l_ac(S/N 60001-Up (D20a-6)) : Work Equipment Control System : Work Equipment Valve (3/3) (For 3-Point Hitch)
01***08Nut (Op)1
07***11O-Ring (Kit)1
07***15O-Ring,(Without Boom Kickout)1
See all parts with full part numbers in Heavy Parts AI →

DNH020_6L_AC(S/N 60001-UP (D20A-6)) serial number reference

The Product Identification Number (PIN) plate on Komatsu D-series bulldozers is typically located on the front frame casting, on the operator's left side near the radiator support. On larger dozers, it may also appear on the inside of the cab door pillar. Read the prefix as the alphanumeric code preceding the serial number (e.g., DNH020-6L-AC), which identifies the model family, generation (-6), and configuration (AC).

PrefixIdentifies
DNH020-6L-ACDNH020-6L-AC

Frequently asked questions

What engine does the DNH020-6L-AC use?

The DNH020-6L-AC (S/N 60001-UP) is equipped with the D20A-6 engine series.

What is the operating weight of the DNH020-6L-AC?

Operating weight varies by configuration and series. Komatsu small dozers in this class typically range from 8 to 108 tonnes, with specific weights for the DNH020 series depending on the attachment package and undercarriage setup.

What replaced the DNH020-6L-AC?

The DNH020-6L-AC was succeeded by later generations of Komatsu small dozers, including the D21 series and subsequent Tier-compliant models, which feature updated emissions systems and improved operator environments.

What DNH020_6L_AC(S/N 60001-UP (D20A-6)) owners discuss

What engine powers the Komatsu DNH020_6L_AC(S/N 60001-UP (D20A-6)) bulldozer?
The Komatsu DNH020_6L_AC(S/N 60001-UP (D20A-6)) bulldozer is powered by the D20A-6 engine. This engine belongs to the D20 series, which is distinct from the D20P-6, D21P-6, and D21A-6 engines found in other DNH020 variants. The D20A-6 is a diesel engine designed for heavy-duty earthmoving applications, providing necessary torque and power for dozing operations. Specific horsepower and displacement figures for the D20A-6 are not detailed in the provided source text; it is identified as the engine for this specific serial range and model configuration. Variations in engine output may exist depending on the specific configuration or regional emissions package.
What are common hydraulic behaviors and issues reported for Komatsu bulldozers like the DNH020 series?
Komatsu bulldozers, including the DNH020 series, often exhibit hydraulic issues that can mimic engine problems. Common behaviors include slow hydraulic functions, loss of power under load, and systems that work cold but become weak when hot. A key diagnostic pattern is distinguishing between engine-driven hydraulic weakness and hydraulic system leakage. If all hydraulic functions are slow, check the hydraulic oil level, correct oil specification, hydraulic filters, engine RPM under load, and hydraulic oil temperature. If only one function is slow, investigate the specific cylinder, control valve, or hose. Hydraulics that weaken when hot often indicate internal leakage in pumps, valves, or cylinders, or degraded oil. The main safety valve is critical for smooth operation and should be inspected regularly.
What undercarriage wear patterns are typical for Komatsu bulldozers?
Undercarriage wear is a significant maintenance concern for Komatsu bulldozers. Common issues include track tension problems, where tracks repeatedly loosen or become too tight, leading to accelerated wear on rollers, idlers, and sprockets. Worn track pads, bushings, and bearings can cause noise, vibration, and premature failure. Mud or debris packed into the undercarriage can increase resistance and wear. The unique undercarriage design of Komatsu dozers aims for cost-efficiency, but proper tensioning and regular inspection of rollers, idlers, and sprockets are essential. Uneven track wear or pulling to one side may indicate issues with track tension, roller condition, or hydraulic travel circuits.
What are common electrical and sensor issues for Komatsu bulldozers?
Komatsu bulldozers rely heavily on electronic control systems, making them susceptible to sensor and electrical issues. Common problems include intermittent starting, dashboard failures, and random shutdowns, often triggered by faulty sensors or unstable power supplies. Specific error codes related to sensors include issues with the A/C inner and outer sensors, ventilating sensors, sunlight sensors, and various engine sensors like coolant temperature, intake air temperature, and fuel pressure sensors. Electrical faults can also involve the ECM (Engine Control Module), crankcase pressure sensors, and turbo speed sensors. Grounding issues, such as a lost ground on the A/C condenser fan relay circuit, can prevent components from operating.
What engine quirks or performance issues are associated with the D20A-6 engine in this dozer?
The D20A-6 engine in the Komatsu DNH020_6L_AC(S/N 60001-UP (D20A-6)) can experience performance issues related to airflow, fuel delivery, and cooling. Common quirks include loss of power under load, which may be caused by restricted air filters, clogged fuel filters, or issues with the turbocharger. Black smoke from the exhaust can indicate incomplete combustion due to air/fuel mixture problems or injector issues. Engine overheating is another concern, often linked to a dirty cooling package (radiator, oil cooler, charge-air cooler) or low coolant levels. Engine mounts can loosen or damage over time, causing excessive vibration and noise. Fuel system issues, such as water in the fuel or contaminated fuel, can also lead to poor performance.
What should be checked when buying a used Komatsu DNH020_6L_AC(S/N 60001-UP (D20A-6)) bulldozer?
When buying a used Komatsu DNH020_6L_AC(S/N 60001-UP (D20A-6)) bulldozer, critical checks include verifying the engine serial number to confirm it is a D20A-6 engine. Inspect the undercarriage for wear on tracks, rollers, idlers, and sprockets, and check track tension. Test all hydraulic functions for speed and power, both cold and hot. Check for electrical faults by scanning for error codes and testing sensors and gauges. Inspect the cooling system for leaks and cleanliness. Verify the condition of the engine mounts and look for signs of excessive vibration. Check the hydraulic oil level and condition, and inspect filters. Ensure the blade and ripper (if equipped) operate correctly.
What are common Komatsu dozer and hystat issues discussed by owners?
Owners of Komatsu dozers, including models with hystat transmissions, report issues such as blade not moving up or down, and travel problems where the machine will not go forward or backward. These issues can be related to the hystat system, which may involve swapping fluid from a final drive to the hystat or other hydraulic circuit problems. While some Komatsu models like the D5G are praised for reliability, others may have more frequent hystat issues compared to other brands. These problems can lead to significant repair costs. It is important to diagnose whether the issue is hydraulic, electrical, or mechanical.

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

Need a specific DNH020_6L_AC(S/N 60001-UP (D20A-6)) part?

Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.

Search parts in the app