Pre Collision System Malfunction: How To Fix? (Step by Step)

Pre Collision System Malfunction

There are few things scarier than an unexpected error message springing up on the dash of your car, and they can be really hard to interpret.

If you’ve been told that your vehicle has a Pre-Collision System malfunction then you’ll want to know what it means and what you can do about it.

A Pre-Collision System malfunction is an error message for Toyota vehicles, and it means that the Pre-Collision System has detected some kind of problem. This system is designed to help detect nearby objects and can provide automatic braking should you fail to react.

Here is how to fix or solve a pre collision system malfunction:

Step 1: Reset the vehicle

Step 2: Reset or recalibrate the Pre-Collision System

Step 3: Investigate the sensors

Step 4: Reset the system

Step 5: Check your ABS and Airbag Sensor

Step 6: Call in a professional

What Is The Pre-Collision System?

Before we get into what this error message might mean and what to do about it, we need to understand what the system actually is and how it works.

The Pre-Collision System in your car is part of what Toyota calls their Toyota Safety Sense. This is a collection of safety features that come as standard in most new models, and are built-in to provide additional protections for you, your passengers, pedestrians, and other drivers as well.

In particular, the Pre-Collision System with Pedestrian Detection (PCS w/PD) detects when a vehicle or pedestrian appears in the direction that the car is moving, and it gives you audio and visual warnings on the central console to make sure that you are aware of their presence.

If you do not avoid the hazard yourself, the system will automatically apply the brakes for you.

Some of these systems will also be able to detect nearby bicyclists and motorcyclists as well as pedestrians or other vehicles.

What Does A Pre-Collision System Malfunction Mean?

So, what does it mean when your car tells you that there is a “Pre-Collision System Malfunction”? Basically, it means that there is some problem within this system that is preventing it from functioning normally, and this can be caused by a number of different things.

The most common causes for this kind of error are:

  1. The sensors are dirty or obstructed. If the front-facing sensors become dirty or are covered (either the radar sensor, the sensor cover, or the camera) then they will not be able to read the road in front of them. Therefore, they cannot detect potential collisions and the car will register that the system has malfunctioned.
  2. There is a technical error in the system. As with any computer-based technology, it might be a flaw within the software or the settings that is causing your Pre-Collision System to fail.
  3. One of the components is misaligned or dislodged. If the components have been moved and are not calibrated correctly, then the system will be unable to accurately scan the road. Some of the components could also have become disconnected from one another, causing a break in the system.
  4. One of the components is damaged. Any of the complex component parts can become damaged or wear down over time, causing the system to stop working.
  5. VSC has been disabled. If you have disabled your Vehicle Stability Control system, this will mean that your Pre-Collision System won’t work properly.
  6. There is a fault with your ABS or airbag sensor. If your Anti-lock Braking System or airbag speed sensor is not working accurately, or your pump is defective, then this can also register as a malfunction in your PCS.

How To Fix A Pre-Collision System Malfunction

Now that we know what your Pre-Collision System is, and what it might mean when it malfunctions, we can talk about the steps you might need to take in order to get it working again.

Step 1: Reset the vehicle

The first thing you should do is try resetting the vehicle to see if this recalibrates the system or not. It’s a simple case of turning it off and on again.

Make sure you are parked in a safe space, turn the engine off, wait for about 10 minutes, then turn it back on again. This can sometimes be enough to reset everything to normal.

Step 2: Reset or recalibrate the Pre-Collision System

You can have a look at how the Pre-Collision System is currently set up, and you can also try deactivating the safety features for at least 10 minutes and then reactivating them, which may reset it back to functioning normally again.

To change the Pre-Collision System settings:

  • Find the Meter Control Switch on your steering wheel.
  • Use the up and down buttons to select the Settings menu (denoted by the symbol of a gear) on the central display.
  • Scroll to the Pre-Collision System (a symbol of two cars colliding, with a star in between them) using the buttons.
  • Hold the central button for two seconds to open the Pre-Collision Systems menu.
  • Press the central button again to deactivate the system, or select one of the three different sensitivity settings. The middle setting is the default.

Then, simply repeat this process again to turn it back on. You should also make sure that your Vehicle Stability Control system is activated and has not been disabled.

Step 3: Investigate the sensors

If the system is still not working, take a look at the sensors themselves. Make sure they are positioned correctly, they are not dirty, and they are not obstructed by anything that has been placed in front of them – like an aftermarket grille.

If you have installed a lift kit to your vehicle, this can also cause the sensors to be misaligned and stop working correctly, as it will affect how far away from the road they are.

You may need to realign the radar using some washers or take it to a professional to have the system recalibrated.

Step 4: Reset the system

If this doesn’t do enough, then you can try resetting all of the electronic systems in your car by disconnecting the battery and then reconnecting it. While you’re doing this, you can take a look to see if any damage has affected the wiring, any connections are loose, or any fuses have blown.

Step 5: Check your ABS and Airbag Sensor

You should also have a look at the sensors for your ABS system and your Airbag system to see that they are also calibrated properly, they are accurately detecting your speed, and the automatic braking options are functioning. This can be tricky to do by yourself, so you may need to go on to the next step here.

Step 6: Call in a professional

If you’re struggling to figure out what is wrong, and the steps above have not helped, then it is probably time to visit a professional mechanic who can diagnose the problem for you.

It may be that components you cannot access have failed, or that the software needs recalibrating in a way that is a little more technical, but they should be able to get it working again.

How Does The Pre-Collision System Work?

There are a few different components that make up the Pre-Collision System in your Toyota, as well as the software and electronic elements that do all of the necessary computing for it to function. The way it works is:

  • Your Toyota has a forward-facing camera and a laser that read the road in front of the vehicle.
  • These two devices measure the distance between the car and any objects that appear in their field of view.
  • The system also measures your speed, to determine whether or not an impact is likely.
  • When the system determines that you could potentially collide with an object in front of you, it warns you with an alarm and a visual alert on the central display.
  • If the system calculates that you have not taken the necessary measures to avoid a collision, it may attempt to automatically apply the brakes, or use brake assist to fully deploy them.

Some older Toyota models will come with Pre-Collision only, which is part of the original Toyota Safety Sense Package.

Newer models will have a Pre-Collision System with Pedestrian Detection, which uses a millimeter-wave radar mounted on the grille to detect even smaller objects and identify potentially vulnerable people in the car’s path.

At What Speed Does Pre-Collision System Work?

The Pre-Collision System is most effective at detecting vehicles and automatically braking when the car is moving at anywhere between 7 mph and 110 mph. When you are moving more slowly, it is harder for the system to determine whether or not a collision is likely, and you may need to be more vigilant.

The system usually applies speed reduction if you are traveling at more than 25 mph and kicks in when there is a difference in speed between you and another vehicle of within 38 miles per hour. Even if you are moving more slowly, it will automatically apply the brakes if it deems that a collision is imminent.

Where Are Pre-Collision Sensors Located?

If you want to check the sensors for your Pre-Collision System, then you need to know where they are.

The radar laser is located in the middle of the grille at the front of the vehicle. Usually, it is either behind the radiator grille or below the Toyota badge. The front-facing camera is typically located at the center of the windscreen, either on the back of the internal rear-view mirror on at the base of the windscreen itself.

Of course, these sensors can be in different positions depending on the exact model of Toyota that you have, so you may need to check your manual in order to find them.

Should I Clean The Sensor Or Replace It?

If the sensor looks a little worn, then you might be wondering: how do I know if my sensor is dirty or actually needs replacing?

The easiest way to check is to give it a good clean, and see whether or not that solves the problem. It is pretty easy for dirt or debris to get onto the sensor and affect its functioning, and it’s a lot cheaper to simply clean it up rather than buy a whole new one.

If cleaning the sensor doesn’t solve your problem, then it’s probably time to replace it.

Does Collision Cause Engine Damage?

You might be wondering whether or not you need your Pre-Collision System at all, or whether you could just turn it off and ignore the error message.

At the end of the day, all of the Toyota Safety Sense features are incredibly helpful and can help to prevent a collision. Any level of collision, no matter how minor, can cause damage to the car’s engine – or other important parts of your vehicle.

It’s better to spend a little time and effort fixing your Pre-Collision System rather than spending a huge amount of money and going through a lot of hassle repairing and replacing parts of your engine after an accident – not to mention the potential harm this could cause to you or others.

Toyota Pre-collision system failure: Ideas of what might be the problem >> Check out the video below:


So, what is a Pre-Collision System malfunction? This error message is telling you that there is some issue in the Pre-Collision System of your Toyota, which is designed to warn you of impending collisions and automatically apply the brakes if you don’t take action.

Usually, this message means that the system is not calibrated properly and needs resetting, the sensors are dirty or obstructed, or there has been some damage to one of the component parts that enable it to work correctly.


Steve P.

Steve is an automotive technician, technical writer, and Managing Editor. He has held a lifelong passion for cars, with a particular interest in cars like the Buick Riviera. Steve is based in Boise, Idaho.

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