Mazda Problems

It’s a bit silly, isn’t it? There’s absolutely no reason for a speedo in an Australian delivered car to read to 260km/h, particularly in a car that would never manage to gain that much velocity without the help of a mine-shaft. There’s no ADR requirement for it, either, so it’s probably a hang-over from other markets where average freeway speeds are much higher than they are here. In Germany, for instance, where there are still unrestricted sections of autobahn, the 200-plus-km/h speedo makes more sense.

You’re probably right when you suggest this is all a one-size-fits-all approach by Mazda (and many other car-makers) who can save a few dollars by making only one speedo calibration and fitting it to cars for every market. More recently, a lot of cars have both a conventional and a digital speedometer fitted. Many owners have come to rely on the latter for clarity. My preference is for an analogue (needle) speedometer that has 100 or 110km/h at the 12-o’clock position on the dial.

An open circuit on a fuel injector is usually caused by either a broken wire to the injector, a loose terminal somewhere in the electrical circuit that drives the injector or a burned-out coil in the injector itself.

Changing the suspect injector will tell you if the coil is the problem, but if that doesn’t fix it, you’ve got to work backwards from the injector until you find the fault. Bear in mind that if the injector itself is at fault, the other three injectors might be ready to go out in sympathy. Modern common-rail engines can be hard on injectors and they sometimes need replacing before they’ve done 100,000km.

The CX-5 is a well regarded vehicle in the trade with a good reputation for going the distance and remaining reliable. However, that’s a lot of kilometres for any vehicle.

Which means, you must approach this one purely on its individual merits. That starts with the service history. Unless you can find a complete, detailed record that proves the car has been absolutely maintained correctly, you could be taking a huge punt. You’d also want to learn as much as you can about who owned it and how it was driven. For instance, 300,000km of gentle highway running is a lot different to the same distance in city traffic or towing a trailer around.

Even then, it would want to be really cheap as you might easily find it’s getting very close to the end of its useful life. That said, a well maintained, carefully driven CX-5 can cover this sort of mileage, so maybe this one has some life left in it. Maybe.

Mazda (and other car-makers) have been having lots of problems with the oil level rising in the engines of some of their diesel models. The problem is caused by the Diesel Particulate Filter attempting to regenerate itself. In an ideal world, these diesel vehicles would be driven for at least an bour or so at freeway speeds at least once a month. That would get the exhaust system hot enough for the DPF to regenerate on its own (burn the contaminants from the exhaust to ash and expel them, basically).

But in cars that don’t see this sort of use and are more commonly driven around the suburbs at moderate speeds, the exhaust never gets hot enough for this to occur. So, the solution has been to inject extra diesel into the engine to make the exhaust hotter and, therefore, get it all to a temperature where DPF regeneration can occur. The problem is that some of that diesel can get into the sump of the engine where it dilutes the engine oil. And that’s why you’re seeing the level rising on the dipstick over a period of weeks and months.

Diluted engine oil is bad news because it may not lubricate and protect the engine as well as non-polluted oil. The warning light you’re seeing is telling you that you might be at that point and that an engine oil change is probably a good idea, even if the service interval hasn’t been reached yet. Just draining some of the contents of the sump away is not the answer as the oil is already diluted by the diesel.

There does seem to be a bit of a trend here where the Mazda software won’t talk to its owners’ phones. It’s not just a Mazda thing, either; plenty of car-makers using proprietary software receive customer complaints when the software and apps won’t play ball.

Some owners have had success by disconnecting the car’s battery overnight and forcing a reset to factory settings, but in other cases, the refusal to operate correctly is intermittent.

However, it’s up to Mazda to make good on a fix for this. Whether that involves replacing the head unit and screen with a new one, downloading new software or a patch for the existing stuff or whatever the solution is, your factory new-car warranty should cover this. Make sure the fault has been logged at the dealership (so Mazda knows it’s a pre-existing condition) and don’t be afraid to tackle Mazda Australia’s customer service division to see what can be done.

You should be guided by your mechanic’s quote for either outcome. In some cases, solenoids are relatively cheap to buy and don’t require too much labour to replace. But, depending on the vehicle, they can also be very expensive and require more or less a full transmission strip-down to remove and replace.

You also need to assess the condition of the whole transmission as putting new parts into a worn gearbox will only delay the inevitable.

I’d be taking a long, hard look at the battery. When a battery is at the end of its useful life, it will often show a 12-volt charge with a simple volt-meter check. But, when you turn the key and place a big load on the battery, it goes weak at the knees and won’t turn the engine over.

Have the battery load tested. This will tell you more about what’s going on. The reason the car started with a jump-start form another car is that the second car’s battery has stepped up to do the job your car’s battery can’t.

This is a really common problem with this model (and the Ford Ranger with which it shared its mechanicals). Many buyers avoid this model for this very reason. Even though many fixes have been tried it seems that this car, shown a hill and a hot day, will often overheat.

Several theories exist including that the EGR valve is the problem, as it fails and allows coolant to escape (usually into the engine cylinders). But even when the EGR valve is working properly, this engine is prone to running too hot. Some other theories hold that the thermal management of the engine itself was just underdone and there’s no real fix for it. That’s borne out by the number of people who have tried different radiators, thermostats and cooling fans and still have a vehicle that overheats.

But you could try reverse flushing the radiator and making sure than every part of the cooling system is working efficiently and properly. That will maximise your chances of not having the engine overheat but, in this case, there are no promises.

That’s not a bad innings for a four-cylinder engine, even a modern one (although I’ve seen similar engines with more kilometres and still going strong). There’s a fair chance the piston rings and valve stem seals have lost some of their mojo and are allowing the oil to be burned in the engine. It’s normal wear and tear, but it needs to be fixed on the basis of the pollution being produced from the tailpipe. Also, eventually, something major will fail spectacularly and leave you stranded.

Your options include rebuilding the current engine or finding a second-hand engine with fewer kilometres on board and simply swapping it into your car. Thanks to the fact that the Mazda 3 was a popular car with younger drivers, they’re somewhat over-represented in wrecking yards, often with engines in very good condition. This would certainly be cheaper than rebuilding your current engine.

Any time a fuel-injected car can’t get fuel from the tank to the engine, the number one suspect is the electric fuel pump. These are often located inside the fuel tank and have a finite lifespan. And when they stop, they just stop. That’s it; no warning and only a new pump will get you going again.

However, it’s also worth checking that you don’t have a blocked fuel filter or a kinked fuel line or something equally random that is stopping the fuel getting to the engine. Nine times out of ten, however, the fuel pump will be the culprit.