Back to catalog
Isuzu
MU-X
RJ (2nd gen)·
2020-2026
suv-4wd
Value
Price (AUD)
$40k-$75k
Body styles
5-door wagon (7-seat)
Drivetrain
Rear-wheel drive (4x2), Part-time 4WD (dual-range, Terrain Command rotary 2H/4H/4L) with rear diff lock on higher 4x4 grades
Origin
Japan
Built in
Thailand
Overview
Sold as LS-M, LS-U, LS-T and the flagship X-Terrain. The second-generation MU-X shares its all-new ladder-frame platform with the RG D-Max ute and is the value-for-money pick of the seven-seat 4WD wagon class - genuinely capable off-road with part-time dual-range 4WD via a Terrain Command rotary dial, a rear diff lock on the upper grades, Rough Terrain Mode traction control, 800mm wading depth and a class-leading 5-year/unlimited-km warranty. The mainstay is the proven 3.0L 4JJ3-TCX turbo-diesel (140kW/450Nm), upgraded for this generation with a 3500kg braked tow rating. From 2022 Isuzu added the smaller, more efficient 1.9L RZ4E-TC (110kW/350Nm) on lower grades, and the late-2025/2026 facelift introduced a new 2.2L RZ4F diesel (120kW/400Nm) with an 8-speed auto and 3500kg towing across the range. Like all modern diesels it has a DPF (Isuzu calls it a DPD) that dislikes short urban trips, plus the usual EGR/intake soot housekeeping - otherwise the driveline is robust and cheap to run by class standards. Watch the standard suspension under heavy loads, the transmission heat when towing hard, and front CV/wheel-bearing wear on hard-working examples.
Engines & variants
3.0L 4JJ3-TCX turbo-diesel
Engine
3.0L common-rail turbo-diesel I4, DOHC 16v, intercooled variable-geometry turbo, DPD
Config
I4 turbo
Displacement
2999cc
Power
140kW @ 3600rpm
Torque
450Nm @ 1600-2600rpm
Drivetrain
RWD (4x2) or part-time 4WD (dual-range)
0–100
~10s
Economy
8.3 L/100km combined (claimed); ~9-11 real world
Tow (braked)
3500kg
Tow (unbraked)
750kg
Transmission
6AT (Aisin)
Timing chain / belt / gear
Chain-driven
Pros
- Proven, torquey 3.0 4JJ-family diesel with a strong reliability record
- 450Nm and a genuine 3500kg tow rating for this generation
- Chain-driven timing - no belt service
- Class-leading 5yr/unlimited-km warranty and cheap capped-price servicing
- Simple, robust driveline that runs to high km with maintenance
Cons
- DPD/DPF dislikes short urban-only running
- EGR and intake soot need periodic cleaning
- Mechanical (not hydraulic) valve clearances - adjustment is a scheduled item
- Standard suspension feels underdone with big loads
- Auto can run hot towing heavy uphill
Known problems
medium
DPD/DPF soot loading and frequent regens on short trips
The Diesel Particulate Diffuser won't passively regenerate on short, low-speed suburban driving. Soot builds up, regen cycles become frequent, fuel use climbs and a permanently blocked filter is expensive. Using non-DPF-rated oil clogs it fast. Some owners have reported constant-regen behaviour and warranty disputes where Isuzu cited fuel contamination.
Fix: Give it a 20-30 minute highway run periodically to complete a burn, use only low-SAPS DPF-rated oil, address blockages early. Cleaning/forced regen is far cheaper than filter replacement.
medium
EGR valve and intake manifold carbon build-up
Soot and oil vapour clog the EGR valve and inlet manifold, causing check-engine lights, hard starting, power loss and rough idle; the EGR can stick open. A catch-can reduces oil carry-over.
Fix: Intake/EGR clean (aerosol kit ~$100, full clean/replacement up to ~$1500); fit an oil catch-can to slow re-fouling.
medium
Transmission overheating when towing heavy
The Aisin auto can run hot dragging a 2.5t+ caravan uphill, with the temperature warning appearing under sustained load from torque-converter slip.
Fix: Fit an auxiliary transmission cooler, use a lower gear on climbs, and keep transmission fluid fresh.
low
Front CV joint and wheel-bearing wear
Front CV joints and wheel bearings can wear earlier than expected on 4x4s used off-road or working hard - a click-clack on full lock signals a tired CV; bearings can fail before 50,000km on hard-used examples.
Fix: Inspect/repack bearings at service intervals, check CV boots for splits, replace worn joints with quality parts.
1.9L RZ4E-TC turbo-diesel
Engine
1.9L common-rail turbo-diesel I4, DOHC 16v, intercooled VGS turbo, DPD
Config
I4 turbo
Displacement
1898cc
Power
110kW @ 3600rpm
Torque
350Nm @ 1800-2600rpm
Drivetrain
RWD (4x2) or part-time 4WD (dual-range)
0–100
~12s
Economy
7.4 L/100km combined (claimed); ~8-9 real world
Tow (braked)
3000kg
Tow (unbraked)
750kg
Transmission
6AT (Aisin)
Timing chain / belt / gear
Chain-driven
Pros
- Notably more economical than the 3.0 (~7.4 L/100km claimed)
- Quiet, refined and surprisingly torquey for its size around town
- Higher payload than the 3.0 in some configurations
- Cheaper buy-in on LS-M/LS-U grades
- Mechanically simple, chain-driven, well-regarded engine
Cons
- 3000kg tow rating (down from the 3.0's 3500kg) and works hard loaded/towing
- Same DPD/EGR emissions housekeeping as the 3.0
- Tight injection tolerances make it sensitive to fuel contamination
- Cold turbo noise reported by some owners
- Modest power for a heavy seven-seat wagon when fully laden
Known problems
medium
DPF/DPD blockage on short trips
The small-displacement diesel runs a higher relative DPF load and won't regen properly on short suburban drives, leading to soot loading, frequent regens and eventual blockage if neglected.
Fix: Regular highway runs to complete a burn; DPF-rated oil only; clean/regen early before the filter needs replacing.
medium
Turbocharger wear / cold-start noise
Owners report loud turbo noise when cold or under load; the factory turbo has had revisions and Isuzu extended turbo warranty on some D-Max/MU-X units, indicating early-life concerns.
Fix: Let the engine idle ~30s before shut-down after hard running to cool the turbo; replace with updated unit if the turbo is noisy/failing.
medium
EGR / intake carbon and fuel-system sensitivity
The EGR operates across a wide range and fouls with carbon, fouling the intake and causing low-rpm hesitation and rough idle. The tight common-rail tolerances also make it intolerant of contaminated/water-laden diesel.
Fix: Periodic EGR/intake clean, fit a quality secondary fuel filter/water separator, use clean diesel; catch-can helps.
2.2L RZ4F turbo-diesel (2026 facelift)
Engine
2.2L common-rail turbo-diesel I4, DOHC, intercooled VGS turbo, DPD (Euro 5)
Config
I4 turbo
Displacement
2164cc
Power
120kW @ 3600rpm
Torque
400Nm @ 1600-2400rpm
Drivetrain
RWD (4x2) or part-time 4WD (dual-range)
0–100
~11s
Economy
6.7 L/100km combined (claimed)
Tow (braked)
3500kg
Tow (unbraked)
750kg
Transmission
8AT
Timing chain / belt / gear
Chain-driven
Pros
- Replaces the 1.9 with more power/torque (120kW/400Nm) and a 3500kg tow rating
- New 8-speed auto improves response and economy (~6.7 L/100km claimed)
- 60% more torque at 1000rpm than the 1.9 - much better off the line
- Carries over the MU-X's strong warranty and value proposition
- Chain-driven, no timing belt
Cons
- Brand-new engine/transmission combo - limited long-term reliability data in AU
- Still a DPF/EGR diesel with the same urban-driving caveats
- Costs more than the 1.9 it replaces
- Heavier seven-seat wagon still works the 2.2 when fully laden
Known problems
low
Unproven new engine and 8-speed transmission
Introduced with the 2026 facelift, the RZ4F and its new 8-speed auto have little real-world AU history yet, so early-build teething issues can't be ruled out.
Fix: Buy with the factory warranty intact, keep full service history, and monitor for any service bulletins/recalls.
medium
DPF/DPD and EGR housekeeping
As a Euro 5 diesel it carries the same DPD plus EGR, which load up with soot on short urban trips and need periodic attention.
Fix: Regular highway runs to allow regen, DPF-rated oil, periodic EGR/intake cleaning.
Common problems (all variants)
medium
Standard suspension underdone under load
The factory springs/dampers sag and feel soft when carrying seven people plus gear or with a loaded towball, hurting stability, steering feel and braking - a common complaint on touring/towing examples.
Fix: Fit a certified GVM/suspension upgrade (constant-load springs, better dampers) matched to the intended load.
medium
Chassis/body cracking with heavy bar and winch
Front rails can flex and cause cracking around suspension towers, inner guards and bull-bar mounts when a heavy steel bar and winch rock under off-road loads.
Fix: Use a properly engineered, lighter bull-bar; inspect mounts and inner guards; repair/reinforce affected sections.
low
Valve clearance check (3.0 mechanical lifters)
The diesels use mechanical valve adjustment rather than hydraulic lifters; clearances drift over time, giving a cold-start tick and, if neglected, valvetrain wear.
Fix: Adjust valve clearances on schedule (rocker-cover gasket/injector seals while in there).
low
Infotainment / electronic gremlins
Owners report occasional touchscreen lag/freezes, Apple CarPlay/Android Auto dropouts and minor electronic glitches on early RJ examples.
Fix: Software updates at the dealer; reset/replace head unit under warranty if persistent.
low
Brake wear / heavy-vehicle braking
As a heavy seven-seat wagon the MU-X is hard on front brakes, especially loaded or towing, with pads and rotors wearing faster than a lighter SUV.
Fix: Quality pads/rotors; consider upgraded pads for regular towing duty.