Isuzu MU-X Problems

The first thing to check is the fluid level in the transmission. Consult the owner’s manual for the correct method of doing this (sometimes the engine needs to be running and the transmission at operating temperature, in other vehicles everything needs to be cold, so this is important).

Low transmission fluid can cause all sorts of problems with gear selection, flaring between gears and actually making the vehicle drive, so that’s why this is the first step. If the level (and the condition) of the fluid is fine, then you need to start looking deeper, and a transmissions specialist is probably your best bet there.

The transmission is a sealed system, so any drop in the fluid level suggests a leak somewhere that needs to be fixed or the problem will return.

Beyond that, running a transmission that isn’t behaving properly can cause damage to the unit itself, so continuing to drive the vehicle in this state is not a good idea.

Even though your caravan is not at the towing limit of your vehicle, more than 2000kg still puts a pretty big load on the Isuzu’s engine. And that, simply, put, is why it’s using its gearbox to keep the engine happy and revving at the appropriate speed to safely make the power and torque you require to move that caravan at highway speeds.

The short answer is that you won’t be hurting the engine by allowing the gearbox to determine what gear it needs to be in. Quite the contrary, and over-riding the transmission to force the vehicle into a too-high gear would, indeed, damage things by overloading various components.

Short of fitting a more powerful engine, there’s not a lot you can do about this. After all, you’ve taken a two-and-a-bit tonne vehicle and more than doubled its weight (with the caravan) meaning you’re asking it to do twice as much work with the same engine. Fundamentally, you can’t beat physics.

The minimum recommended tyre pressure for your car is 230kPa. That’s equal to about 34psi in the old money. Bear in mind that’s the minimum Isuzu recommends. So 210kPa is definitely too low.

But don’t be tempted to use the tyre’s appearance as a guide to it inflation pressure. Most time, you won’t visually pick a deflated tyre until it reaches below 20psi, at which point it’s already dangerously low. Even parking on a sloped piece of road can make a tyre look underinflated thanks to the weight of the vehicle distorting the tyre’s sidewall.

Using 230kPa is the minimum, you’d definitely increase pressure if you were towing a trailer, were fully loaded or travelling at freeway speeds on a hot day. And don’t be too trusting of your tyre gauge if it’s throwing up low readings all the time. Check it against another gauge to see if there’s a discrepancy. And don’t be at all be tempted to trust the tyre pressure gauge at a service station. The modern, automated tyre inflaters are better, but the old hand-held ones are constantly left out in the weather, thrown on the ground and run over by fuel tankers.

You’ve kind of already answered your own question by saying that you’ve already waited a year for delivery. Saying no to this one and ordering another might see a similar delay and you’d be back to square one. And a year older. Like many brands, Isuzu deliveries were adversely affected by global supply-chain problems and the world shortage of silicon-chips needed to make on-board computers work.

There are two issues with a car with last year’s build date. The first of these is that the motor trade uses the year of manufacture when calculating retained (trade-in) value. So, if you don’t plan to keep the car long before trading it in, then maybe that’s a concern. If you plan to keep it for 10 years or so, then an extra birthday will have very little affect on its trade-in value by then. This is something you might be able to negotiate on with the dealership you’ve purchased from

As for warranty, Australian Consumer Law states that motor vehicle warranties start form the date of first registration, not the build date. So even though the car might technically be six months old when you get it, the factory six-year/150,000km warranty will start from the day it’s delivered to you as a brand-new vehicle. The exception to this is if the car was originally a dealer demonstrator, when the warranty would start form the time it was registered by the dealership. If that’s the case, this should be reflected in the purchase price as it’s no longer a brand-new car you’re buying.

It's true that new engines can be 'tight' and this can lead to higher fuel consumption than they achieve with a few more miles on board. And since you're almost at the 30,000km mark now, why not try the dealer's advice and see if things start to improve.

The MU-X was never the most fuel efficient vehicle in its class, but even so, 12.2 litres per 100km on the highway sounds a little excessive (although not as much as you might think). I'd expect this vehicle to return highway fuel economy figures closer to 10 litres per 100km or maybe a bit less.

However, there are several factors that might be skewing your results. The bluff aerodynamics of a vehicle like the MU-X mean that even a slight headwind can increase consumption. So can the addition of accessories such as a bull-bar and roof racks. A set of roof racks on their own can add a litre of fuel to every 100km travelled, and that's if they're not loaded. Throw a spare tyre and some gear up there and it's even worse.

Bigger (taller) tyres can also increase fuel consumption, and so can running your tyres at too low a pressure.

This needs to be sorted out quickly as a car that you can't be sure is in Park is always a potential to roll away on its own causing who knows what grief and damage. It sounds like there's something amiss with the way the gear selector is talking to the actual transmission, and any resistance in the action of the shifter really shouldn't be there. That said, you do need to have your foot on the brake to select a gear from Park, so maybe you're taking your foot off the brake pedal prematurely.

You're possibly correct that the two issues are related as a car that thinks it's not in Park, will probably not want to allow you to use the walk-away locking mode. But here's the good news: This is absolutely a warranty issue and Isuzu needs to fix it at its cost.

Book the car in to be inspected as soon as possible and, in the meantime, make sure it's parked somewhere from which it can't roll away. Physically chocking a wheel (with a house-brick, a rock or whatever) isn't a bad idea till it's fixed, either.

This sounds like a case of low transmission fluid. Check the transmission dipstick according to the instructions in the owner's manual to see if the level is where it should be. Low fluid level can cause all sort of problems from slipping to a lack of drive to uneven shifts and shifts occurring when they shouldn't. Also, try to find out what fluid was put in the transmission when it was last serviced. The wrong type or grade of fluid can cause the same types of problems as not enough fluid.

If the fluid checks out, then you need to start looking at other causes such as glitches in the on-board computer that controls the driveline. An electronic scan of the vehicle would be the next step.

It sounds very much like the transmission is confused electronically or has a problem with its valve body which is supposed – in conjunction with the computer – to make decisions about what gear the transmission should be in. Perhaps it's as simple as a dodgy electrical connection somewhere and the impact of potholes or buffeting from passing trucks is causing a short-circuit somewhere.

The first piece of advice, however, is to not drive the vehicle any farther. You not only risk damaging the transmission, but it's also dangerous to drive a vehicle that might suddenly select the wrong gear at random. The second piece of advice would be to take the vehicle to a dealership and have its computer scanned to see if any fault codes have been recorded. If your local dealer doesn't want to know, take it straight to head office and contact Isuzu's customer service division.

The good news is that your vehicle is still under the factory warranty, so make it Isuzu's problem, not yours. Just make sure that the behaviour has been logged as a problem, at which point it's classed as a pre-existing condition and Isuzu is still obliged to fix it even if the warranty runs out.

It doesn't matter whether it's a common fault with this make and model, because the reality is that the vehicle is still under the factory warranty, so it's Isuzu's problem, not yours.

Provided, that is, that the fault occurred on its own and not as the result of an impact that would be deemed accidental damage.

Generally speaking, these LED information screens and other touch screens are pretty reliable and robust, but problems have been known to occur including loss of touch control and the sort of crazing you're noted. Isuzu is not alone either, and many brands have similar issues. The crazing can also be the result of temperature extremes (hot and cold) and will sometimes go away when the ambient temperature returns to a more moderate level.

The type of problem can often be fixed by replacing the actual screen (or in this case, rotary dial) rather than the entire control unit. But it's a specialist job and involves dismantling at least some of the dashboard to achieve.

This is not an uncommon complaint with MU-X owners nor the owners of many other makes and models. It seems as though some Bluetooth systems prefer an Apple phone to an Android and vice-versa. The solution for some owners has been to change their brand of phone, but that seems pretty extreme. Others have resorted to aftermarket Bluetooth systems, but since your car is still brand-new, it doesn't make sense to be changing the head unit.

The first thing to do is contact Isuzu to see if there's been a new download to reflash the head unit and improve the Bluetooth performance. Car makers constantly chase this stuff, and a reflash might suddenly make the thing play the game properly.

You can check whether the problem is phone incompatibility by trying to pair somebody else's phone (of a different type) to see if it works properly with the MU-X's system.