Isuzu MU-X Common Problems

The Isuzu MU-X is a seven-seat 4WD wagon built on D-Max underpinnings, with a ladder frame and the same 3.0-litre diesels. The first generation ran from late 2013 to 2021 with the 4JJ1-TCX and a five-speed automatic. A 2017 update added Euro 5 emissions, a diesel particulate filter (Isuzu calls it a DPD) and a six-speed auto. The second generation arrived in 2021 with the stronger 4JJ3-TCX, a six-speed automatic and Isuzu's IDAS driver-assist suite, and a 1.9-litre RZ4E was later offered in some two-wheel-drive versions. Owners rate the engine and towing ability highly. Most complaints are about the body structure, emissions hardware and driver aids rather than the engine.

Engine bay inner guard cracking (first generation, 2014 to 2021)

The MU-X shares the D-Max front structure, and owners of both report cracks in the inner guards and suspension towers above the front wheels. Soft front body mounts are often part of the story. Cracks are reported less often on the MU-X than on the D-Max, but they do occur, and bull bars, winches and corrugated roads make them more likely. Repairs mean replacing sections of the inner guards, which can take weeks and is likely to cost several thousand dollars out of warranty.

DPD regeneration problems (3.0 diesel, 2017 to 2026)

MU-X wagons from the 2017 update on carry a DPD. Short school runs and suburban driving stop it from burning off soot, so owners see frequent regeneration messages, warning lights and, in bad cases, limp mode. Newer cars appear to be programmed to regenerate more often, and an interrupted burn may restart on the next drive. A regular half-hour highway run helps. A workshop can force a regeneration or clean the filter for a few hundred dollars, and a replacement costs several thousand.

EGR valve and intake carbon build-up (3.0 diesel, 2014 to 2026)

Like the D-Max, the MU-X builds carbon in its EGR valve and intake manifold. Symptoms are rough idle, hard starting, lost power, worse fuel use and a check-engine light. Intake cleaning sprays at service time slow it down. A stuck EGR valve has been quoted at around $1,500 to replace. Blanking off the EGR is illegal.

Automatic gearbox heat and shift faults (5-speed and 6-speed autos, 2014 to 2026)

The MU-X is a popular caravan tow car, and hard towing on long climbs can overheat the automatic. A temperature warning may only come on once damage is done. There is also an isolated owner report of a first-generation six-speed car refusing to shift up or dropping into a limp gear. Constant gear changes while towing are usually normal behaviour. For serious towing, fit an auxiliary cooler, change the fluid more often than the book says, and check fluid condition before you buy.

Rear main seal and transfer case leaks (3.0 diesel, 2014 to 2017)

A few owners report that early 3.0 engines in the MU-X and D-Max had a sealant problem at the rear main seal, with leaking seals replaced under warranty. Owners also report transfer case and diff pinion seal leaks. Check under the car where the engine meets the gearbox. A rear main seal replacement needs the gearbox out, so labour makes it an expensive job. Some oil use is normal for this engine, and Isuzu has been quoted as accepting up to 700 ml per 2,000 km.

Driver-assist false braking and lane-keep intervention (IDAS, 2021 to 2026)

On the second generation, owners complain that automatic emergency braking reacts to shrubs, shadows and parked cars, and that lane-keep assist fights the driver when passing wide loads or on narrow roads. Some systems switch back on at every start. Covering the cameras can cause other faults and may affect insurance. Test the systems on your drive.

Recalls and safety

Second-generation MU-X wagons share recalls with the D-Max. These include a lower steering shaft bolt that might not be tightened to specification (2020 to 2022 builds) and a recall has also been reported for engine control software that could reduce engine speed and cause a stall. Whichever generation you look at, ask an Isuzu dealer to check the VIN for open recalls, and see our recalls page.

Buying a used Isuzu MU-X? What to check

• Inner guards: Look above both front wheels and around the suspension towers for cracks, fresh paint or welding.
• DPD history: On 2017 and later cars, ask how it was driven and whether the DPD has been cleaned or replaced.
• Cold start: Start it cold and listen for rough idle or a top-end tick, as the valve clearances need periodic adjustment.
• Gearbox: Check for smooth upshifts through every gear and ask what it has towed and whether a cooler is fitted.
• Oil leaks: Look under the engine, gearbox and transfer case for fresh oil, and check the dipstick level.
• Front end: Listen for CV clicks on full lock and check for uneven front tyre wear or worn wheel bearings.
• Towing wear: Look for a sagging rear end, a worn towbar and an electric brake controller, which point to heavy caravan use.
• IDAS: On a 2021 or later car, drive in traffic and on a country road to see how the driver aids behave.

Run a PPSR check for finance owing and write-off records, and take our Isuzu MU-X buying checklist to the inspection.

The verdict

A 2014 to 2016 first-generation MU-X is the simplest choice for short-trip drivers because it has no DPD, but check the inner guards closely and expect an older cabin. The 2017 to 2021 cars add the DPD and a six-speed auto and suit highway and towing use. The second generation from 2021 is the most refined, with the strongest engine and best safety, but confirm the recalls are done and live with the driver aids before you buy. Avoid any MU-X with cracking, gearbox overheating history or heavy modifications.