Pump up your attention or pay



Mistakes at the pump can be costly.

Sometimes it’s not until your vehicle breaks down on a petrol station forecourt, or it sputters to a halt as you try to leave the station, that you realise you’ve filled your car with the wrong fuel. Either way, it’s a truly frustrating, time-consuming and costly experience. But, it’s not something to feel embarrassed about, as it happens all over New Zealand on a regular basis — so much so, that companies now exist to come to our aid and get us back on the road after filling up with the wrong fuel. There are even devices that can prevent this from happening in the first place.


Motorists with multiple cars — or those who drive fleet pool vehicles regularly — are probably the most likely to make the mistake of filling up with the wrong fuel. To avoid this, all it takes is just a quick double check of the fuel that’s required for the vehicle, often shown on a sticker inside the petrol flap.

It’s more common for motorists to put petrol into a diesel system than the other way around and, unfortunately, it also has the potential to be the most damaging and costly error to make. Diesel fuel pumps operate on very fine tolerances and they’re lubricated by the viscose diesel fuel. If you run petrol through a diesel system you’ll strip the lubricant, causing the pumps to run dry and ultimately damage them from the metal to metal contact.

If your vehicle has a common rail (CRDi or HDi) diesel engine, it pays to be extra cautious as repairs or replacements after filling up with the wrong fuel can be very expensive.

If the fuel pump is damaged or contaminated fuel reaches the common rail system, you’ll need to pay for the fuel pumps, injectors, fuel rail, filters and tank to be cleaned out and you might even need replacements.

The process and cost of repairs will depend upon the type of vehicle you have and how long you’ve been running or attempting to run your car on the incorrect fuel.

In worst-case scenarios, bills can be thousands of dollars — especially if a large chunk of the fuel system requires replacement and repairs to the engine are necessary.

If your vehicle is under warranty, it also pays to consult the manufacturer or the warranty company. They may have guidelines or policies on the cleaning and replacement process you should follow to ensure you remain covered and to prevent further issues.

Many vehicles now have an electric, low-pressure pump in the fuel tank that operates the moment you turn on the ignition. So if you’ve just put the wrong fuel in your car and turn on the ignition, it will soon be circulating its way through the fuel system, causing damage in a matter of seconds. Leaving the ignition off gives you a good chance of minimising the damage and you may need only to get the tank drained and topped up with new fuel to be able to get you on your way again.

If you have to learn the hard way, hopefully it’s this option.

Diesel users will be aware they need to unlock the pump before using it. Picking up a petrol pump without having to unlock it first should automatically trigger warning bells. This may explain why fuelling your petrol vehicle with diesel is less common, but it still happens.

After putting diesel in a petrol car you’ll probably find that the engine may just simply fail to start or if it does, it’ll soon sputter out afterwards. In some cases your car may continue to run but you’ll certainly notice that it’s not running as well as usual. Typically your car will display symptoms as well, such as pinking (a noise from the engine), exhaust smoke and a loss of power.

If operated for extended periods of time, you also run the risk of internal damage to the engine. For most cases, repairs usually involve draining the fuel, changing fuel filters, flushing fuel lines and possibly cleaning the spark plugs and injectors before filling up with the correct fuel.

If you ever fill up with the wrong fuel, there are companies throughout New Zealand that can come to your rescue — as long as you haven’t touched the ignition. For a very expensive fee, they can suck out the contaminated fuel from your car’s tank, letting you refill and hit the road in no time.

A petrol fuel nozzle is a cheaper alternative that prevents you from actually putting the wrong fuel into your tank in the first place. Products available in New Zealand go by the name of Dieselhead, which simply fastens in the place of the original fuel cap. The filler will only receive a diesel filler nozzle and won’t fit the smaller petrol nozzle that’s at service stations. You don’t have to worry about putting the wrong fuel in your car again — plus it even comes with an external cap to stop unwanted fuel or water drops from entering the filler when activated.