Car remapping – the ultimate guide

remapping car ECU

Everybody wants to get the most out of their car, and with remapping, you can. While the regular car owner might not dare tiptoe into the world of car mapping, hard-core car enthusiasts might insist on rewriting their car’s Engine Control Unit (ECU).

What is remapping a car?

Remapping involves altering the settings of a car’s ECU, also called ECU tuning or chip tuning. Your car’s ECU will come with its own preset configuration, but this can be overwritten. 

Traditionally, remapping meant plucking the old ECU out of a car and replacing it with a new one, also known as ‘chipping’. Technology has since moved on. You can usually rewrite the factory ECU that came with your car, or at least, take your car to a professional to do so. This will involve accessing the chip via the OBD (On Board Diagnostics). 

Some modern cars may restrict access via the OBD for security. In that case, the ECU needs to be removed manually and connected to an external computer. Alternatively, a second, external ECU may be used instead. This can be a useful option as it keeps the car’s original state, just adds another ECU which can also be removed easily if you ever choose to trade in or sell your car.

What does the ECU do?

A car’s ECU governs several important functions of the vehicle, including:

  • Airbags
  • Door locks
  • Emergency braking
  • Engine responsiveness

Obviously, these are all very, very important aspects of your car, and accidentally altering the correct function of any of them could be catastrophic. Therefore, unless you are properly educated in the programming and safe running of vehicles, car remapping isn’t something you should try at home.

what is car remapping
Car engines rely on the ECU to tell them how to respond to driver commands.

What does ECU remapping a car do?

Engine remapping can change the way car engines act when you drive, and for many enthusiasts and racers, it’s how they make their car run precisely how they want. There’s a reason racers, in particular, would want to remap their cars, and that’s because it can amp up the power and torque of a vehicle. 

At factory settings, there’s a good chance your car isn’t designed to run at full power. This can be for all manner of reasons, from compliancy to economical choices made by the manufacturer. It’s also the reason the same car can be released as a more powerful version — all it takes is a change to ECU programming.

Advantages of car remapping:

  • Improved ignition timing
  • Better throttle and engine response
  • Extra power and torque when climbing 
  • Better air/fuel ratio
  • Improved turbocharging boost pressure

Disadvantages of car remapping:

  • Demanding more from your engine can demand more servicing
  • You may need to change to a pricier, higher octane fuel
  • You may struggle to adapt to the higher power at first
  • Insurance companies may not approve remapped vehicles for cover
  • Your car warranty may be voided if you remap your car
  • Car softwares get updated often, which will replace your custom settings. So, you’ll have to rewrite the ECU every time your car gets a maintenance service 

How much does remapping cost?

A car remap will usually set you back around £300, but can be cheaper or more expensive depending on what’s involved. 

Of course, the cost of remapping your car can hit you in other ways. This includes higher insurance premiums or struggling to find cover at all. It may also void your warranty so you won’t be covered if anything happens to your car. There’s also the fact that making your car more powerful may require a change in fuel, which can be more expensive.

If you leased your car, or bought a car on finance, you may find that remapping it will impact your contract. As a general rule, you should assume every third party involved with your car, from insurance, to the manufacturer, isn’t going to like remapping. The best thing to do is to call them and see exactly what remapping your car will change from their perspective.

Accessing a car ECU
Often, the ECU can be accessed through the dashboard.

Can all cars be remapped?

No, not every car can be remapped. Usually, your car will need to have been bought after 2000 to feature the required technology. Remapping is most often used on turbo diesel engine cars. Don’t assume your car can be remapped, and don’t assume it will always be worth it. Ask a professional and see if they believe your car can benefit from remapping.

Where can I find ECU remapping near me?

Most garages should be able to help you with remapping. Do your research and find a reputable professional who is experienced in remapping and chipping cars. We don’t recommend that you try it yourself, or entrust your car to anyone who will be performing a DIY job. 

Does car remapping improve fuel efficiency?

This depends on the car. Generally, more power and higher speeds mean you’ll be using up more fuel. In some cases, though, remapping your engine can help your car more efficiently use its fuel, this is something a professional can tell you. 

What does it mean to have a DPF removed?

You may here remappers talk about how cars should also have the DPF removed if your aim is duel economy. A DPF is a diesel particulate filter, and it helps filter soot from the exhaust. This can also lead to build-up and required deep-cleaning that can be expensive. Some car enthusiasts believe that diesel engines with the DPF removed will enjoy better fuel economy. 

Will remapping damage my car?

So long as you are using a professional to have your car remapped, it shouldn’t damage your vehicle in any way. 

Will remapping make my car perform better?

While the main argument for remapping is a more powerful engine, don’t think that manufacturers have watered down your car’s power on purpose. There are plenty of reasons behind the factory settings of your car’s ECU, including its performance in extreme temperatures, challenging weather conditions, when towing and load etc. By remapping your car, it may be in the optimum condition for regular driving, but not for more challenging circumstances. 

Do I need to inform my insurance company that I have remapped my car?

Yes, you may need entirely new cover for modified cars. In some cases, your current provider may refuse to continue to cover you based on these sorts of alterations, so always tell your insurance provider if you plan to remap your car and plan accordingly.

How do I know if my car is remapped?

If you have purchased a used car, it may well already be remapped. A professional will be able to tell you, though in some cases, you can visibly see the external ECU. 

Looking to sell your car?

If remapping has peaked your interest, you’ll need a relatively modern car (post-2000) to take advantage of it. Sell your used car with Motorway — here are some handy guides on selling your vehicle:

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