Mazda Keyless System Malfunction – How To Deal with the Problem?

A keyless entry system allows locking and unlocking of the doors by pressing the small button on the door handle of your Mazda. This is a modern feature that has become standard for more and more models of the Japanese car manufacturer. This article examines the Mazda Advanced Keyless Entry System, addresses the problem of the keyless system malfunction, and offers possible solutions.

Keyless system malfunction message highlights

• Common reasons:12V battery low, key battery low, 12V battery connections loose
• How to fix:change the key battery, charge the 12V battery, tighten the terminals
• Possible consequences:you may need to use manual key start
• Priority level:Medium
• Can you drive?Yes
• DIY repair:Possible
• Repair price range:$5-$250

What does it mean when your Mazda says "Keyless System Malfunction"?

This message means that you no longer can use the keyless entry feature. Your small button on the door handle may not function and the car may not start when you try to press the engine start button.

When you see this message, you may use the alternative way of starting the car which will work with more or less any Japanese vehicle with the keyless entry:

• get into the vehicle using the unlock button on your fob or, if it doesn't work, use the metal key that you can extract from your fob;
• turn on the accessory mode by pressing the engine start button - you will not start the car and will see the "Keyless System Malfunction" message;
• press the brake pedal so that your car can be started now;
• use your key fob and press the engine start button exactly with the fob - this will help your vehicle identify the key.

This is easy and straightforward. But it won't work in some cases. The problem is that the "Keyless System Malfunction" error is pretty sticky and will be there on the screen for a long time. Your ECU may get a glitch that will not allow it to start the vehicle. So even if you are pressing the engine start button with the fob, it may not start.

In this case, you will need to reset the system because, without this, it's not likely that the Mazda will ever start.

How to reset the "Keyless System Malfunction" message in the Mazda vehicle?

First of all, you should understand that sometimes, this message tells you about deeper problems than just a glitch in the software. So, it may happen that the reset will not clear the message. But it will most likely let you drive the car.

Here's what you should do:

• locate the 12V battery in your Mazda;
• disconnect the negative terminal, then disconnect the positive one;
• press honk so that the remaining power is released;
• wait for 5 minutes to let all the control units turn off completely;
• connect the positive terminal of the battery, then the negative one;
• now try starting the car with the method I described above.

Mazda describes this method here - have a look at the more detailed instructions.

Also, if the car doesn't show you the "Keyless System Malfunction" error message, you may use the usual method to start the engine - just press the engine start button while pressing the brake pedal. Everything should work just fine. If the message is still there, you will still be able to start the car by pressing the engine start button with the fob.

What are the reasons for the "Keyless System Malfunction" message?

The reason why you see this message may be one of the following:

1. The key fob battery is dead or weak

In this case, the antenna in your car will not be able to recognize the key or it will recognize the key but will also spot that the signal is weak. There is a special code in the ECU for a low key fob battery.

I won't describe the process of battery replacement - here's the official Mazda manual for this.

2. The 12V car battery is low

Low voltage may make your car go crazy. So, if the car battery is weak, the vehicle will not start and the electronic modules will go mad throwing all kinds of different messages. One of the common warnings you will see is the keyless system problem warning that we are talking about today.

To check this, you may need to charge the battery with a charger or at least with a booster. You may also jump the battery from another car. Checking it with the multimeter is not efficient because the bad battery can still show 12-12.5 volts when not under load.

So, just charge your battery. If it's 5 years old or even older, you may buy a new battery and install it. In most cases, car batteries just don't live more than 4-5 years.

3. The wiring and connections problems

In the Mazda CX-5, for example, there is a very common issue of the exterior keyless entry antenna disconnecting. It may trigger the "Keyless System Malfunction" message and also block the little button functions on the door handle of your SUV.

The antenna is placed in the driver's door and to get to it, you will need to take off the plastic interior panel. The connector is really shabby and may fall off when you drive on a bad road. Connecting it back will solve the problem.

Also, keep in mind that the reset may be needed with an OBD2 scanner or by disconnecting the battery in order to let everything work well.

4. The software issues

You shouldn't forget that Mazda pretty often has glitchy software. Your immobilizer may have a glitch and just trigger this message and prevent the engine from starting. This is a serious problem unless you know how to reset the control modules. Actually, the reset procedure is easy and it was described earlier in this article - for this, you will need to disconnect the 12V battery.

Still, if after the battery reset your Mazda feels good and starts with a button push, you should have the car inspected in the dealership or in a good trusted repair shop. Maybe, there is a problem you didn't notice and it eventually can leave you stranded on the road.

Can you drive when your keyless system freaks out in the Mazda car?

If your vehicle starts when you press the engine start button with a key, you can drive. The "Keyless System Malfunction" error message will most likely disappear in several minutes and you will be able to drive safely.

The only possible issue that may prevent you from driving is alternator issues that lead to battery drain and will soon lead to no-power problems in your vehicle. Alternator problems will also affect all other electric and electronic modules, so you won't miss them. Also, in this case, the battery warning light will most likely be illuminating on the dash at all times.

Other than that, nothing holds you from driving the vehicle. This message only tells you that there may be some problems with entering the car with the keyless entry features and also starting the car with the button. But if you are already in the Mazda and can start the engine by pushing the button with the key fob, you are good to go.

What to do if nothing helps you get rid of the message?

Of course, this may be quite annoying to see this message every time you get into your car. This means something is still wrong with the car. You've tried replacing the key fob battery, recharging and disconnecting the 12V battery, using the OBD2 scanner to see some possible error codes, and even looking at the connections in your keyless entry antenna in the driver's door. But the error message is still there. What should you do?

In this case, I recommend you go to the dealership and have the car inspected. Mazda dealers are not cheap, this is not a secret. But if your Mazda is under warranty, the repair and inspection will be free for you. If the warranty is already over, you can pay for the inspection, learn about the culprits of the problem, and then go to the independent shop and have your car repaired.

Unfortunately, without professional repair, it's impossible to solve the problem that can't be fixed with all the DIY repair methods that I've proposed in this article. Digging in the electronics of your Mazda car is only wise if you have the proper expertise and professional tools for that.

Final thoughts

I know that seeing the "Keyless System Malfunction" error message in your Mazda vehicle is not that pleasant. You may even start panicking because now you can't start the car by just pushing the button. But if you follow the simple guidelines that I provide you with in this article, you will be able to resolve the majority of possible problems that triggered this message.

Also, now you know when exactly you can go to the dealership or to the shop and let professionals do the job for you. I hope you will never have problems with your Mazda. And even if you do, you will obviously find the answers to your questions on the pages of this blog.