Pre-Collision System Malfunction (Causes & Fixes)

Pre Collision Malfunction

Modern vehicles possess a safety feature dubbed a pre-collision system (PCS). It operates using a fusion of sensors, cameras, and radar that identify potential accidents and then instantly put on the brakes to ward off or reduce the implications of a crash.

However, sometimes this system may malfunction, leading to false alerts, failure to detect potential collisions, or unnecessary braking system activation.

A pre-collision system malfunction occurs when there is an issue with the system's sensors, software, or hardware, leading to improper functioning of the PCS.

This malfunction can compromise the safety of the vehicle occupants and other road users, making it essential to address the issue promptly.

In this article, we will talk about the causes of pre-collision system failure, how to diagnose and fix the issue, and how to prevent it from happening in the first place.

How Does the Pre-Collision System Work?

The pre-collision system (PCS) is a cutting-edge safety feature featured in modern vehicles that utilizes a combination of sensors, cameras, and radar to detect potential collisions and responds with brakes when applied automatically. Its design is to avoid and contain the effect of a crash.

The PCS blends multiple sensors, such as millimeter-wave radar, laser sensors, and cameras, to identify possible obstructions and other vehicles that may block the car's route.

These sensors can sense the gap, velocity, and path of objects, helping the system decide if the potential danger of a collision is imminent.

The computer system integrated into the vehicle collects and interprets the data to figure out if a likely collision could occur.

The system can identify a range of likable collision circumstances, including rear-end collisions, head-on collisions, and collisions with pedestrians.

After the sensors have perceived a possible collision risk, a visual and audio alert will prompt the driver to take emergency action.

Should the driver neglect to take action, the system will apply the brakes directly to prevent or reduce the effect of a collision.

In some situations, the system may adjust the vehicle's handling and suspension to avoid obstacles or keep the car steady during unexpected maneuvers.

In the event of a collision, the PCS may also switch on the post-collision safety system of the vehicle, which may automatically switch off the engine, free the doors, and activate the hazard lights to caution other drivers.

Common Causes of Pre-Collision System Malfunctions

Like any complex technology, the PCS is susceptible to malfunctions, which can compromise the system's effectiveness and pose a safety risk.

Here are some of the common causes of Pre-Collision System Malfunction:

1. Sensor Issues

One of the most common causes of PCS malfunction is sensor issues. The system's sensors can become dirty, blocked, or damaged, preventing them from accurately detecting obstacles and other vehicles.

This can lead to false alarms or a failure to detect potential collision risks.

2. Calibration Issues

The PCS relies on accurately calibrating the sensors, cameras, and other components to function effectively.

Any calibration issues can lead to inaccurate sensor data, false alarms, or failure to detect collision risks.

3. Electrical Issues

The PCS is an electronic system that relies on a complex wiring network and electrical components.

Any faults or damage to the electrical system can cause the system to malfunction, leading to false alarms or a failure to detect collision risks.

4. Software Issues

The PCS uses complex software to analyze sensor data, detect potential collision risks, and initiate the appropriate response.

Any software issues, such as bugs or glitches, can lead to false alarms, failure to detect collision risks, or inappropriate system responses.

5. Environmental Factors

Environmental factors such as heavy rain, snow, fog, or bright sunlight can interfere with the PCS's sensors and cameras, leading to false alarms or a failure to detect collision risks.

6. Human Error

Finally, human error can also cause PCS malfunction. Drivers may accidentally deactivate the system or fail to keep the sensors and cameras clean and free of obstructions, leading to false alarms or a failure to detect collision risks.

How To Diagnose Pre-Collision System Malfunction

Diagnosing a pre-collision system (PCS) irregularity can be demanding, as it requires understanding the system's elements and operations.

Nevertheless, utilizing the suitable apparatus and methodologies, diagnosing PCS flaws, and taking on any problems correctly is achievable.

Here is an in-depth glance at how to identify Pre-Collision System dysfunction:

1. Check for Warning Lights

The first step in diagnosing a PCS malfunction is to check for any warning lights on the dashboard.

Most modern vehicles will have a PCS warning light to illuminate when the system detects an issue.

If there is a warning light, taking the car to a qualified mechanic or dealership is essential to diagnose the problem.

2. Inspect the PCS Sensors

If there is no warning light, the next step is to inspect the PCS sensors. The sensors are usually located in the front grille or bumper of the vehicle.

They can become dirty, blocked, or damaged over time. Inspect the sensors for any visible damage or debris blocking them.

3. Check the Electrical System

The PCS uses a complex network of wiring and electrical components to function effectively.

Check the electrical system for any faults or damage that may be affecting the system's performance.

4. Test the PCS Functions

To test the PCS functions, drive the vehicle in a controlled environment, such as an empty parking lot, and simulate potential collision risks.

This can include approaching a stationary object or vehicle at different speeds and observing how the PCS responds. If the PCS is not responding appropriately, it may indicate a malfunction.

5. Check for Software Updates

Sometimes, PCS malfunctions can be due to outdated or faulty software. Check with the vehicle manufacturer or dealership to see if any software updates or patches are available to address the issue.

6. Consult with a Professional

Consulting with a professional mechanic or dealership is essential if the issue cannot be diagnosed or addressed using the above methods.

They will have the tools and expertise to effectively diagnose and fix any PCS malfunctions.

How To Prevent Pre-Collision System Malfunction

Preventing pre-collision system (PCS) malfunction is crucial to ensure the system's effectiveness in detecting and preventing potential collision risks.

Here are some tips to avoid PCS malfunction:

1. Keep PCS Sensors Clean

PCS sensors are essential system components and can become dirty, blocked, or damaged over time.

Keep the sensors clean by regularly washing the vehicle and removing any debris or dirt blocking them.

2. Avoid Modifying PCS Components

Modifying the PCS components, such as the sensors, cameras, or wiring, can affect their effectiveness and cause the system to malfunction.

Avoid any modifications to the system and consult with a qualified mechanic or dealership if any changes are necessary.

3. Check PCS Warning Lights

If the PCS warning light illuminates the dashboard, it indicates a potential malfunction in the system.

Check the warning light regularly and take the vehicle to a qualified mechanic or dealership to diagnose and fix any issues promptly.

4. Maintain Electrical Components

The PCS uses a complex network of wiring and electrical components to function effectively.

Regularly maintain the electrical components, such as fuses and relays, and repair any faults or damage affecting the system's performance.

5. Update PCS Software

Regularly updating the PCS software ensures that the system functions effectively and efficiently.

Check with the vehicle manufacturer or dealership for any software updates or patches that may be available and install them promptly.

6. Drive Safely and Responsibly

PCS is for detecting potential collision risks and preventing accidents, but driving safely and responsibly is crucial.

Follow traffic rules and regulations, avoid distracted driving, and maintain a safe distance from other vehicles to reduce the risk of collision.

Pre-Collision System Pros and Cons

While PCS offers significant benefits, it also has its advantages and disadvantages.


1. Increased Safety

PCS provides an additional layer of safety to drivers, passengers, and pedestrians by detecting potential collision risks and applying the brakes automatically to prevent accidents.

2. Reduces Collision Risks

By detecting and preventing potential collision risks, PCS reduces the risk of road accidents, injuries, and fatalities.

3. Advanced Technology

PCS uses advanced technology, such as cameras, sensors, and radar, to detect potential collision risks, making it an innovative and efficient safety feature.

4. Driver Assistance

PCS provides driver assistance, helping drivers avoid collisions, especially in challenging driving conditions, such as bad weather or heavy traffic.

5. Insurance Discounts

Many insurance companies offer discounts to drivers who have PCS installed in their vehicles, as it reduces the risk of accidents and claims.


1. False Alarms

PCS can sometimes generate false alarms, causing the brakes to engage unnecessarily, leading to sudden stops and accidents.

2. Expensive Repairs

PCS is a complex system that requires specialized knowledge and tools to repair, making it expensive to fix if it malfunctions.

3. Limited Performance in Certain Conditions

PCS may not function correctly in certain driving conditions, such as heavy rain, fog, or snow, reducing its effectiveness in preventing collisions.

4. High Cost

PCS is an expensive safety feature that adds to the cost of a new vehicle, making it less accessible to lower-income buyers.

At What Speed Will Toyota's Pre-Collision System Work?

Toyota's pre-collision system (PCS) is an advanced safety feature designed to detect potential collision risks and automatically apply brakes to prevent accidents. The system's effectiveness varies depending on the vehicle model and speed.

Typically, Toyota's PCS operates effectively at speeds up to 37 miles per hour (60 kilometers per hour).

However, some Toyota models have PCS that can work at higher speeds, up to 90 miles per hour (144 kilometers per hour).

It is imperative to remember that the PCS does not replace prudent driving techniques nor guarantees the avoidance of crashes entirely.

It has been constructed to aid drivers in preventing or softening the consequences of accidents, signaling them to possible threats and, if necessary, furnishing extra braking help.

It's crucial to maintain the system regularly and keep the sensors clean to ensure accurate detection of potential collision risks to maximize the effectiveness of Toyota's PCS.

Drivers should also follow traffic rules and regulations, avoid distracted driving, and maintain a safe distance from other vehicles to reduce the risk of collision.