2019 — 2026
6.7L Cummins High Output I6 (ISB 6.7 HO)
Diesel
Check service history for the 'Y78' CP3 recall conversion on 2019-2020 models (2021+ models switched back to CP3), and listen for high-pitched whining from the engine bay during acceleration. | Note: The factory CP4.2 fuel pump on 2019-2020 models is prone to catastrophic failure from low-lubricity NZ diesel or water contamination, ruining the entire common-rail system unless recalled or upgraded.
Test the Aisin AS69RC 6-speed automatic transmission at low speeds, shifting manually from 1st to 2nd, and feel for harsh clunking or hesitation during deceleration downshifts. | Note: The HO Cummins is paired with the commercial-grade Aisin transmission. While highly durable for towing, it operates much more harshly than the standard Ram ZF 8-speed and is expensive to repair in NZ if abused.
Access the vehicle's EVIC (Electronic Vehicle Information Centre) cluster to check the DPF soot level, and check for active 'Exhaust Filter Full' warnings during a highway test drive. | Note: NZ's typical short-trip driving cycles do not allow the massive 6.7L engine to reach optimal operating temperatures, leading to rapid DPF soot accumulation and costly SCR/AdBlue system faults.
Conduct a 'dry park test' by having an assistant wiggle the steering wheel back and forth while you inspect the front steering linkage, track bar, and steering damper for play. | Note: The immense weight of the 6.7L Cummins iron block puts extreme stress on front suspension components, often causing premature wear of ball joints and steering boxes on undulating NZ rural roads.
Replace both primary (chassis-mounted) and secondary (engine-mounted) fuel filters using genuine Fleetguard elements, and perform a comprehensive grease service on the front driveshaft.
Drain and refill the Aisin transmission pan, replace the internal transmission fluid filter, and change the fluid in both the front/rear differentials and the transfer case.
Replace the Crankcase Ventilation (CCV) filter element located on top of the valve cover, perform a valve lash adjustment inspection, and execute a complete cooling system flush.
Always use premium API CK-4 low-ash 5W-40 or 15W-40 engine oil to protect the complex emissions control systems and high-output valvetrain.
Replace both fuel filters concurrently every 20,000 km or 12 months; never skip this, as the common-rail injectors are highly sensitive to microscopic debris.
Only use high-grade, fresh Diesel Exhaust Fluid (AdBlue) from sealed containers to prevent crystallisation and sensor failures inside the DEF tank heater assembly.
Regularly lubricate the front driveshaft double-cardan grease point, which is frequently missed by generalist NZ service centres during routine maintenance.
Torque the heavy-duty rear dual-wheel lug nuts (on dually models) and front wheel hubs to factory specifications at every tyre rotation to prevent stud shear.
Estimated repair costs if issues arise
Requires replacing the pump, all six injectors, fuel lines, fuel rails, and thoroughly flushing the fuel tank to remove metal shaving contamination.
High cost due to heavy-duty internal component pricing and the specialist labor required to overhaul this commercial-grade automatic transmission in NZ.
If the exhaust particulate filter or selective catalytic reduction system becomes irreversibly soot-damaged or cracked, replacement parts must be imported.
Replacing worn factory ball joints with heavy-duty aftermarket units (e.g., Carli or Synergy), along with a new track bar and steering stabiliser.
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Disclaimer: This report is generated with the assistance of AI analysis based on verified automotive data. While we strive for 100% accuracy, enthusiasts should always conduct physical inspections and consult service records. View Full Disclaimer