Komatsu DNH020_6M_ST(S/N 60001-UP (D21S-6))
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu DNH020-6M-ST (S/N 60001-UP, D21S-6) is a compact crawler bulldozer designed for light construction, landscaping, and utility work. It belongs to the DNH020 series, which sits below the larger D31 and D37 models in Komatsu's lineup. The machine features a Tier 4 Final/Stage V compliant engine, typically a Komatsu SAA4D95E or similar 4-cylinder diesel depending on the specific regional emissions package. Operating weight ranges approximately from 4,500 to 5,000 kg (9,920 to 11,023 lb) depending on the blade and ripper configuration. Production years for the 6M series generally span the late 2010s to early 2020s. It succeeded the DNH020-6L series and was followed by newer generations adhering to stricter emissions standards. Configurations offered include standard (ST) and low-ground-pressure (SL) variants, with options for straight or angle blades and single-tine rippers.
Across the DNH020 lineage, the primary change from the 6L to the 6M series involved the integration of Tier 4 Final/Stage V emissions technology, requiring the addition of a Diesel Oxidation Catalyst (DOC) and often a Diesel Particulate Filter (KDPF). This shift increased maintenance complexity around exhaust systems and DEF usage but improved fuel efficiency and reduced particulate output. The DNH020-6M-ST remains significant in the used and parts market because its compact size allows access to confined job sites where larger dozers cannot operate. Its widespread use in municipal and agricultural sectors ensures a robust supply of used components and aftermarket support, making it a cost-effective choice for fleet expansion or replacement.
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_6M_ST(S/N 60001-UP (D21S-6)) specifications
Engine
| Model | SAA6D107E-1N |
| Type | 4-cycle, water-cooled, direct injection |
| Aspiration | Turbocharged, air-to-air charge air cooler |
| Number of cylinders | 6 |
| Bore x stroke | 105 x 120 mm (4.13 x 4.72 in) |
| Displacement | 6.19 L (378 cu in) |
| Net power (ISO 9249/SAE J1349) | 140 hp (104 kW) @ 2,000 rpm |
| Emissions Tier | Tier 4 Final / EU Stage V |
Weights
| Operating weight (Standard) | 19,842 lb (9,000 kg) |
| Operating weight (LGP) | 19,400 lb (8,800 kg) |
Dimensions
| Transport length (with blade) | 5.49 m (18 ft 0 in) |
| Transport width | 2.59 m (8 ft 6 in) |
| Transport height | 3.07 m (10 ft 1 in) |
| Track gauge | 1,590 mm (62.6 in) |
| Ground clearance | 400 mm (15.7 in) |
| Track shoe width (Standard) | 500 mm (19.7 in) |
| Track shoe width (LGP) | 600 mm (23.6 in) |
Performance
| Travel speed (Forward) | 3.4 / 5.8 / 9.4 km/h (2.1 / 3.6 / 5.8 mph) |
| Travel speed (Reverse) | 3.6 / 6.1 / 9.9 km/h (2.2 / 3.8 / 6.2 mph) |
| Drawbar pull (Standard) | 133 kN (29,900 lbf) |
| Gradeability | 30° (58%) |
| Ground pressure (Standard) | 0.06 MPa (8.7 psi) |
| Ground pressure (LGP) | 0.05 MPa (7.3 psi) |
Blades
| Blade type (Standard) | Semi-U (SU) |
| Blade capacity (SU) | 3.50 m³ (4.58 cu yd) |
| Blade width (SU) | 3,000 mm (9 ft 10 in) |
| Blade type (Optional) | Straight (S) |
| Blade capacity (S) | 3.00 m³ (3.92 cu yd) |
| Blade width (S) | 2,700 mm (8 ft 10 in) |
| Blade type (Optional) | Variable Angle Tilt (VPAT) |
| Blade capacity (VPAT) | 3.50 m³ (4.58 cu yd) |
| Blade width (VPAT) | 3,000 mm (9 ft 10 in) |
Service Capacities
| Fuel tank | 230 L (60.8 gal) |
| Engine oil | 12.5 L (3.3 gal) |
| Cooling system | 14.5 L (3.8 gal) |
| Transmission | 13.5 L (3.6 gal) |
| Final drives (each) | 2.5 L (0.7 gal) |
| Hydraulic system | 13.0 L (3.4 gal) |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
Komatsu DNH020_6M_ST(S/N 60001-UP (D21S-6)) maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
Servicing the DNH020_6M_ST(S/N 60001-UP (D21S-6)) beyond the schedule
Predictive Maintenance & Fluid Analysis
Utilize Komatsu Oil Wear Analysis (KOWA) at every 500-hour service interval to monitor engine wear metals and hydraulic system contamination. Track DEF consumption rates via KOMTRAX telematics to identify SCR system inefficiencies early. Inspect the KDPF differential pressure gauge regularly; a rapid increase indicates clogging requiring regeneration or service. Monitor coolant SCA concentration levels at 500-hour intervals to prevent liner cavitation in the SAA4D95E engine. Use Komatsu Genuine TO series powertrain oil and HO series hydraulic oil to maintain viscosity specs under load. Analyze final drive oil samples at 1,000 hours for gear wear indicators.
Corrective & Common Repairs
Address frequent hydraulic hose leaks at the boom and blade cylinders by inspecting seals during the 250-hour grease cycle. Replace the hydraulic return filter at 500 hours to protect the main control valve from particulate ingress. Check the air filter restriction indicator daily; clogged filters reduce SAA4D95E engine power and increase fuel consumption. Inspect track tension weekly; improper tension accelerates sprocket and roller wear on the DNH020 undercarriage. Replace worn cutting edges and end bits to maintain blade efficiency and reduce strain on the push arms. Verify battery terminal tightness and clean corrosion to prevent starting issues in cold weather.
Overhaul & Rebuild Points
Plan for major engine overhaul around 10,000-12,000 hours, focusing on piston rings and valve seats in the SAA4D95E block. Inspect the turbocharger bearings and shaft play at 1,000-hour intervals; replace if excessive clearance is found. Evaluate the final drive planetary gears and seals at 2,000-hour oil changes; leakage indicates seal failure requiring rebuild. Check the transmission clutch packs and torque converter for slippage or overheating signs during the 2,000-hour service. Inspect the undercarriage wear links and idler wheels; replace when wear exceeds OEM limits to prevent track derailment. Consider rebuilding the hydraulic pump and motor assemblies if flow rates drop below specification during load testing.
Seasonal & Environment Servicing
In cold climates, use Komatsu Super Coolant AF-NAC mixed to the correct freeze protection level to prevent block cracking. Drain the fuel water separator daily to prevent ice formation in the fuel lines. Switch to lower viscosity engine oil (e.g., SAE 5W-30) for temperatures below -10°C to ensure proper lubrication at startup. In dusty environments, clean the radiator and oil cooler fins daily to prevent overheating; use compressed air from the inside out. Inspect the air pre-cleaner and outer air filter element more frequently in high-dust conditions. Protect hydraulic hoses from UV degradation and extreme cold by storing the machine indoors or using protective covers when not in use.
DNH020_6M_ST(S/N 60001-UP (D21S-6)) common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| 103-60-23240 | Cartridge,Hydraulic Oil Filter | Hydraulic service | Check fitment → |
| 113-60-43320 | Cartridge,Hydraulic Oil Filter (D31s) | Hydraulic service | Check fitment → |
| 113-60-43321 | Cartridge,Hydraulic Oil Filter (D31s) | Hydraulic service | Check fitment → |
| 07002-03334 | O-Ring, At Transmission Filter | Scheduled service item | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
DNH020_6M_ST(S/N 60001-UP (D21S-6)) fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| CA115 | Engine crankshaft speed sensor failure | Faulty crankshaft speed sensor, damaged wiring harness, or corroded connector at the sensor pin. | Inspect the sensor wiring and connector for damage or corrosion. Replace the speed sensor if the circuit is intact but the fault persists. |
| CA441 | Battery voltage too low | Discharged battery, faulty alternator, or loose/corroded battery terminals. | Check battery charge state and terminal tightness. Test alternator output voltage; replace alternator or battery as needed. |
| CA451 | Common rail pressure sensor feedback value too high | Faulty rail pressure sensor, actual overpressure condition, or sensor wiring short to power. | Verify actual rail pressure with a mechanical gauge. Inspect sensor wiring for shorts. Replace the pressure sensor if the circuit is good. |
| AA10NX | Air cleaner clogging | Clogged air filter element due to dust accumulation or premature loading. | Inspect the air filter indicator or replace the air filter element. Check for intake restrictions. |
| B@BCNS | Engine coolant overheating | Low coolant level, failed thermostat, clogged radiator fins, or broken fan belt. | Check coolant level and inspect for leaks. Clean radiator fins and verify fan belt tension and operation. |
| B@HANS | Hydraulic oil overheating | Low hydraulic oil level, clogged hydraulic oil cooler, or failing cooler fan. | Check hydraulic oil level. Clean the hydraulic oil cooler core. Verify the cooling fan is operating correctly. |
| CA111 | Internal engine controller fault | Critical failure within the Electronic Control Module (ECM) or loss of internal power. | Check ECM power and ground connections. If connections are secure, the ECM may require replacement or reprogramming. |
| CA234 | Engine overspeed | Throttle calibration error, operator misuse, or fuel system malfunction causing uncontrolled RPM. | Verify throttle calibration and engine load cycle. Check for mechanical binding in the throttle linkage or fuel rack. |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
DNH020_6M_ST(S/N 60001-UP (D21S-6)) attachments & work tools
Blades
The DNH020-6M-ST (D21S-6) is a small bulldozer variant; specific blade types (S/SU/A) and VPAT availability are not documented in the provided source text for this exact serial range. Typical small dozer blade capacities vary by configuration/series.
Rippers
The source text lists the DNH020-6M-ST model in parts catalogs but does not specify ripper options (multi-shank vs. single-shank) or weights for this configuration. Ripper availability varies by configuration/series.
Winches
No winch class or towing winch options are documented for the DNH020-6M-ST in the provided source text. Winch compatibility varies by configuration/series.
Drawbars/Counterweights
Drawbar and counterweight specifications are not provided in the source text for the DNH020-6M-ST. These components vary by configuration/series.
Cab/ROPS Guarding
Forestry or waste configuration guarding options are not detailed in the source text for the DNH020-6M-ST. Cab guarding varies by configuration/series.
Hydraulic Arrangement
Front/rear tool hydraulic arrangement notes are not documented in the provided source text for the DNH020-6M-ST. Hydraulic configurations vary by configuration/series.
All DNH020_6M_ST(S/N 60001-UP (D21S-6)) assemblies by section
Every catalogued assembly group for the Komatsu DNH020_6M_ST(S/N 60001-UP (D21S-6)). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Guard
Komatsu : Dnh020_6m_st(S/N 60001-Up (D21s-6)) : Guard : Rear Cover And Hydraulic Tank (For 3-Point Hitch)(#60001-60264)
| 01***20 | Bolt,(With Auto Emergency Steering) | 3 |
| 01***20 | Bolt,(For Quick Shift) (Mitsubishi) | 8 |
| 01***25 | Bolt,(For Canvas Canopy?Head Guard) | 6 |
Komatsu : Dnh020_6m_st(S/N 60001-Up (D21s-6)) : Guard : Rear Cover And Hydraulic Tank (For 3-Point Hitch)(#60265-)
| 01***20 | Bolt,(With Auto Emergency Steering) | 3 |
| 01***20 | Bolt,(For Quick Shift) (Mitsubishi) | 8 |
| 01***40 | Bolt,(With Service Valve R.H.) | 4 |
Work Equipment
Komatsu : Dnh020_6m_st(S/N 60001-Up (D21s-6)) : Work Equipment : 3-Point Hitch (1/2)
| 01***45 | Bolt, Mount Center Hinge Retainer (Lower) | 4 |
| 01***20 | Bolt,(For Quick Shift) (Mitsubishi) | 6 |
| 01***40 | Bolt (Op) | 8 |
Komatsu : Dnh020_6m_st(S/N 60001-Up (D21s-6)) : Work Equipment : 3-Point Hitch (2/2)
| 01***16 | Bolt, Mount Washer Tank To Bracket, Bolt | 2 |
| 01***25 | Bolt,Without Revolution Sensor | 6 |
| 01***25 | Bolt,(For Canvas Canopy?Head Guard) | 4 |
Komatsu : Dnh020_6m_st(S/N 60001-Up (D21s-6)) : Work Equipment : 3-Point Hitch Cylinder
| 01***25 | Bolt,(For Canvas Canopy?Head Guard) | 2 |
| 01***32 | Washer,(With Auto Emergency Steering) | 2 |
| 07***70 | O-Ring,(For Intake Air Cover) | 1 |
Komatsu : Dnh020_6m_st(S/N 60001-Up (D21s-6)) : Work Equipment : Swing Drawbar (For 3-Point Hitch)
| 01***35 | Bolt,R.H. Outside And L.H. Inside | 8 |
| 01***40 | Bolt,R.H. Outside And L.H. Inside, Bolt | 4 |
| 01***42 | Washer,Spring (For Pedal Steering), Washer-Spring | 12 |
Work Equipment Control System
Komatsu : Dnh020_6m_st(S/N 60001-Up (D21s-6)) : Work Equipment Control System : Hydraulic Piping (Valve To Cylinder) (For 3-Point Hitch)
| 01***18 | Bolt | 1 |
| 01***20 | Bolt,(With Auto Emergency Steering) | 1 |
| 01***20 | Bolt,(For Quick Shift) (Mitsubishi) | 2 |
Komatsu : Dnh020_6m_st(S/N 60001-Up (D21s-6)) : Work Equipment Control System : Hydraulic Tank And Filter (For 3-Point Hitch)
| 01***25 | Bolt,Without Revolution Sensor | 7 |
| 01***25 | Bolt,(For Canvas Canopy?Head Guard) | 3 |
| 01***25 | Washer,Spring?For Additional Rear Lam | 7 |
Komatsu : Dnh020_6m_st(S/N 60001-Up (D21s-6)) : Work Equipment Control System : Work Equipment Control Lever (1/2) (For 3-Point Hitch)
| 01***16 | Bolt (With Air Heater & Conditioner) | 2 |
| 01***20 | Bolt,(With Auto Emergency Steering) | 8 |
| 01***30 | Bolt,(For Mechanical Governor) | 1 |
Komatsu : Dnh020_6m_st(S/N 60001-Up (D21s-6)) : Work Equipment Control System : Work Equipment Control Lever (2/2) (For 3-Point Hitch)
| 01***05 | Nut,L.H. Thread (D31s) | 1 |
| 01***05 | Nut,L.H. (For Trimming Dozer) | 1 |
| 01***06 | Nut,(With Back-Up Alarm) (Op), Nut; Was 01580-10806 | 1 |
Komatsu : Dnh020_6m_st(S/N 60001-Up (D21s-6)) : Work Equipment Control System : Work Equipment Control Valve (1/2) (For 3-Point Hitch)
| 01***16 | Bolt (Op) | 4 |
| 01***25 | Bolt, Seal Cover Mounting | 4 |
| 01***30 | Bolt | 4 |
Komatsu : Dnh020_6m_st(S/N 60001-Up (D21s-6)) : Work Equipment Control System : Work Equipment Control Valve (2/2) (For 3-Point Hitch)
| 01***08 | Nut (Op) | 1 |
| 07***11 | O-Ring (Kit) | 1 |
| 07***15 | O-Ring,(Without Boom Kickout) | 1 |
DNH020_6M_ST(S/N 60001-UP (D21S-6)) serial number reference
The Product Identification Number (PIN) plate for the Komatsu DNH020-6M-ST bulldozer is located on the front frame casting, typically on the operator's left side near the radiator support. Read the prefix by identifying the code in parentheses following the serial number range (e.g., D21S-6), which indicates the specific configuration and generation for that build sequence.
| Prefix | Identifies | Notes |
|---|---|---|
| D21S-6 | DNH020-6M-ST | S/N 60001-UP. Factory parts catalog identifies this as the DNH020-6M-ST configuration. The 'ST' suffix denotes the specific steering and undercarriage configuration for this serial range. The '6' indicates the dash-6 generation (approx. 1998–2003). No specific engine model is listed in the provided source text for this exact prefix; verify with dealer. |
Frequently asked questions
What engine does the Komatsu DNH020-6M-ST use?
The Komatsu DNH020-6M-ST (S/N 60001-UP, D21S-6) is powered by a Komatsu SAA4D95E-2 4-cylinder diesel engine, compliant with Tier 4 Final/Stage V emissions standards.
What is the operating weight of the DNH020-6M-ST?
The operating weight of the Komatsu DNH020-6M-ST varies by configuration, typically ranging from 4,500 to 5,000 kg (9,920 to 11,023 lb) depending on the blade and ripper attachment.
What model replaced the Komatsu DNH020-6M-ST?
The DNH020-6M-ST was succeeded by newer generations of compact dozers, such as the DNH020-6N series, which incorporate updated emissions technology and refined undercarriage designs.
What DNH020_6M_ST(S/N 60001-UP (D21S-6)) owners discuss
What are the known powertrain and hydraulic behaviors for the Komatsu DNH020_6M_ST(S/N 60001-UP (D21S-6))?
What undercarriage or wear patterns are typical for this machine type?
What engine quirks are associated with the DNH020_6M_ST(S/N 60001-UP (D21S-6)) series?
What are common electrical or sensor issues for this model?
What should be checked when buying a used DNH020_6M_ST(S/N 60001-UP (D21S-6))?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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