I. Introduction

1.1 Attention – grabbing opening

Imagine this: You’re leisurely strolling through a parking lot, approaching your parked BYD electric vehicle. As you get closer, to your utter shock, the engine suddenly roars to life without any input from you. The vehicle lurches forward, narrowly missing a passer – by. This isn’t a scene from a science – fiction movie; it’s a real – life incident that several BYD electric car owners have unfortunately experienced. Such unexpected engine startups not only cause a heart – stopping moment but also raise serious concerns about the safety and reliability of these vehicles.

1.2 Purpose of the article

The aim of this article is to dig deep into this perplexing issue of BYD electric vehicles starting their engines without warning. We will explore the potential causes behind this phenomenon, look into how it affects the owners, and discuss possible solutions. Whether you’re a BYD owner, a potential buyer, or simply interested in the world of electric vehicles, this comprehensive analysis will provide you with valuable insights and peace of mind.

II. Incidence of the Problem

2.1 Is it a widespread phenomenon?

The issue of BYD electric vehicles starting their engines without user input is not an isolated incident. A quick glance at platforms like Chezhiwang (a well – known automotive complaint website in China) and various car forums reveals a disturbing number of complaints from concerned owners.

On Chezhiwang alone, there are dozens of entries related to unexpected engine startups in BYD electric models. In July 2023, according to the complaint data monitoring platform of Chepingwang, among the top 10 complaint models, 5 were BYD models, and among the top 15 complaint models, 9 were BYD models. Many of these complaints specifically pointed out that after forced OTA upgrades, the engine frequently started automatically in EV mode. This high volume of complaints indicates that this problem is not limited to a few individual vehicles but has affected a significant number of BYD electric vehicle owners.

2.2 Models involved

A variety of BYD electric vehicle models seem to be affected by this problem. The BYD Tang New Energy is one of the frequently reported models. Owners have complained that even when the vehicle is in EV mode with sufficient battery power, the engine starts on its own. Some have reported that this occurs during parking, while others have experienced it while driving, disrupting their driving experience and raising safety concerns.

The Song PLUS New Energy has also been plagued by this issue. Multiple owners have taken to online platforms to voice their grievances. They’ve noted that after the vehicle was allegedly secretly OTA – updated by the manufacturer, the engine began to start without warning in EV mode. This not only leads to increased fuel consumption and maintenance costs but also creates potential safety hazards, especially in situations like driving through waterlogged areas where an unexpected engine start could cause water to enter the engine.

The Qin PLUS is another model on the list. Owners of the Qin PLUS DM – i have reported that after the company was involved in a certain incident related to fuel tank issues, their vehicles started to have the engine start automatically in EV mode. This has left them feeling frustrated and deceived, as they had initially chosen an electric vehicle for its promised all – electric driving experience.

III. Possible Reasons

3.1 Battery – related issues

3.1.1 Low battery voltage

One of the primary reasons for the unexpected engine startup in BYD electric vehicles could be low battery voltage. The vehicle’s battery is like its heart, powering all the electrical components. When the battery voltage drops below a certain threshold, the vehicle’s system may perceive it as a potential risk to the battery’s health or the overall operation of the vehicle.

To safeguard the battery and ensure that the vehicle can still function properly, it may automatically trigger the engine to start. The engine then acts as a generator, charging the battery back to a safe level. For instance, if the battery has been gradually losing charge due to a parasitic drain (such as a malfunctioning electrical component that continues to draw power even when the vehicle is off), the voltage can drop significantly. Once it reaches a critical point, the vehicle’s protection mechanism kicks in, and the engine starts up without any input from the driver.

3.1.2 Battery management system glitches

The battery management system (BMS) is a complex and crucial component in electric vehicles. Its main function is to monitor the battery’s state, including voltage, temperature, and charge level, and ensure its safe and efficient operation. However, like any complex system, the BMS is not immune to glitches.

If the BMS malfunctions, it may misinterpret the battery’s state. For example, it could wrongly detect that the battery voltage is low or that the battery is in a state of distress, even when it’s actually in good condition. This misjudgment can lead the BMS to send incorrect signals to the vehicle’s central control unit, which in turn may cause the engine to start. A software bug within the BMS, a hardware failure of its sensors, or interference from other electrical systems in the vehicle could all potentially trigger such glitches.

3.2 Electronic control system malfunctions

3.2.1 Sensor failures

The electronic control system in BYD electric vehicles relies on a network of sensors to gather real – time data about the vehicle’s operating conditions. Sensors such as the oxygen sensor, which measures the amount of oxygen in the exhaust gas, and the temperature sensor, which monitors the engine’s temperature, play a vital role in the engine control unit’s (ECU) decision – making process.

When these sensors fail, they can provide inaccurate or erratic data to the ECU. For example, a faulty oxygen sensor might send signals indicating that the engine is running too lean (not enough fuel in the air – fuel mixture), even when it’s operating normally. Based on this false information, the ECU may decide to start the engine to adjust the fuel – air ratio and correct the perceived problem. Similarly, a malfunctioning temperature sensor could report an abnormally high engine temperature, causing the ECU to initiate the engine to cool it down, believing that the cooling system alone is not sufficient.

3.2.2 ECU problems

The engine control unit is the brain of the vehicle’s engine management system. It receives data from various sensors, processes it, and then sends out control signals to different engine components to ensure optimal performance. However, if the ECU itself develops a problem, it can lead to a host of issues, including unexpected engine startups.

A hardware failure within the ECU, such as a malfunctioning microcontroller or a damaged circuit board, can disrupt the normal flow of electrical signals. This can cause the ECU to generate incorrect control commands or even send random signals that may trigger the engine to start. Additionally, software glitches in the ECU’s programming can also be a culprit. If there are bugs in the code that govern the engine’s start – stop logic, it could result in the engine starting at inappropriate times. For example, a flaw in the code that checks for certain vehicle conditions before allowing an engine start could be bypassed, leading to an unprompted engine startup.

3.3 Mechanical system problems

3.3.1 Ignition system faults

The ignition system in a vehicle is responsible for providing the spark that ignites the air – fuel mixture in the engine’s cylinders. In BYD electric vehicles, although the primary power source is electric, the engine still has an ignition system for when it needs to operate. Faults in this system can lead to unexpected engine startups.

For instance, a malfunctioning ignition coil can produce an electrical arc at the wrong time. The ignition coil is designed to step up the vehicle’s low – voltage electrical current to a high – voltage spark that can ignite the fuel. If the coil develops a crack or internal damage, it may leak electricity and create a spark, even when the engine is not supposed to start. Similarly, problems with the high – tension leads (the wires that carry the high – voltage current from the ignition coil to the spark plugs) can also cause issues. A damaged or worn – out high – tension lead can allow the electrical current to escape, creating a spark that could potentially ignite the fuel in the cylinders and start the engine.

3.3.2 Fuel system issues

The fuel system in a vehicle is another area where problems can occur and potentially lead to unexpected engine startups. The fuel pump, for example, is responsible for delivering fuel from the fuel tank to the engine. If the fuel pump malfunctions, it may create a pressure spike in the fuel lines. This abnormal pressure can cause fuel to be forced into the engine’s cylinders, and if there is a spark present (even if it’s not supposed to be there at that time), it can ignite the fuel and start the engine.

The fuel pressure regulator, which controls the pressure of the fuel in the fuel system, can also be a source of trouble. If the regulator fails to maintain the proper fuel pressure, it can result in either too much or too little fuel being delivered to the engine. An over – supply of fuel can create a situation where the fuel is more likely to ignite spontaneously, leading to an unplanned engine start.

3.4 Software – related reasons

3.4.1 OTA upgrade glitches

Over – the – air (OTA) upgrades are a convenient way for manufacturers to update the software in their vehicles without the need for the owner to visit a dealership. However, these upgrades are not always without issues. In the case of BYD electric vehicles, some owners have reported that after an OTA upgrade, their vehicles started to experience unexpected engine startups.

The OTA upgrade may have inadvertently changed the engine – start logic in the vehicle’s software. For example, the new software version might have different criteria for when the engine should start to assist with battery charging or to meet certain emissions requirements. If these changes are not properly tested or if there are conflicts with the existing hardware or other software components, it can lead to the engine starting at inappropriate times. Some owners have specifically pointed out that after an OTA upgrade, the engine started to kick in more frequently in EV mode, even when the battery had sufficient charge.

3.4.2 Software bugs

The software that runs in BYD electric vehicles is incredibly complex, with millions of lines of code. As with any software, it’s possible for bugs to exist. These bugs can be latent and only manifest under specific conditions, such as a particular combination of vehicle speed, battery charge level, and environmental factors.

A software bug could potentially cause the vehicle’s control system to misinterpret the driver’s inputs or the vehicle’s operating conditions, leading to an unexpected engine startup. For example, a bug in the software that manages the transition between electric and hybrid modes could make the system think that the vehicle needs to switch to hybrid mode (and thus start the engine) when it actually doesn’t. Or, a glitch in the software that monitors the battery’s state of health could trigger the engine to start as a precautionary measure, even though the battery is in a perfectly normal condition.

IV. Impact on Vehicle Performance and Safety

4.1 Effects on vehicle performance

4.1.1 Fuel consumption and energy efficiency

The unexpected engine startups in BYD electric vehicles have a significant negative impact on fuel consumption and energy efficiency. When the engine starts without warning, especially in situations where the vehicle was initially operating in all – electric mode with sufficient battery charge, it leads to unnecessary fuel consumption.

Owners of the BYD Tang New Energy have reported that such unprompted engine starts can consume approximately 6 kilometers’ worth of fuel each time. This not only increases the cost of refueling for the owner but also goes against the principle of energy – efficient driving that electric vehicles are supposed to offer.

In terms of energy efficiency, the vehicle’s power management system is disrupted. The battery, which was originally designed to provide power for a certain range of all – electric driving, now has to share the load with the engine. This can lead to a situation where the battery is not fully utilized, and the overall energy conversion efficiency of the vehicle is reduced. For example, if the engine starts and runs for a while, it may consume fuel to generate electricity that could have been more efficiently provided by the battery. This waste of energy not only impacts the vehicle’s performance but also contributes to increased emissions, which is a major concern for environmentally – conscious consumers who choose electric vehicles.

4.1.2 Wear and tear on components

Frequent and unexpected engine startups can cause substantial wear and tear on various vehicle components. The engine itself is one of the most affected parts. Each time the engine starts, there is a sudden surge of mechanical and electrical forces. The pistons, crankshaft, and other moving parts in the engine experience rapid acceleration and deceleration, which can lead to increased friction and premature wear.

The starting system, including the starter motor and the battery, also bears the brunt of these frequent startups. The starter motor is designed to be used intermittently, but when the engine starts unexpectedly multiple times, the starter motor is overworked. This can cause the brushes in the starter motor to wear out quickly, leading to starting problems in the future.

The battery is also put under stress. The repeated engine startups mean that the battery has to supply a large amount of current each time to crank the engine. This can lead to a reduction in the battery’s overall lifespan and capacity. Over time, the battery may not be able to hold a charge as effectively, resulting in decreased all – electric driving range.

In addition, the engine’s lubrication system may not have enough time to properly distribute oil during these short, unplanned engine startups. This can lead to metal – to – metal contact in some parts of the engine, further accelerating wear and tear. As a result, owners may find themselves facing costly repairs and replacements of these components much earlier than expected.

4.2 Safety concerns

The unexpected starting of the engine in BYD electric vehicles poses serious safety risks. In parking lots, for example, a vehicle’s engine starting without warning can cause it to lurch forward or backward suddenly. This unexpected movement can catch nearby pedestrians and other vehicle operators off – guard, increasing the risk of collisions. A driver who is approaching their parked vehicle, assuming it is in a stationary and safe state, could be injured if the vehicle starts moving on its own.

When driving in narrow roads, an unanticipated engine start can also be extremely dangerous. It can cause a sudden change in the vehicle’s power output, making it difficult for the driver to maintain control. The driver may instinctively react in a way that could lead to a loss of control, such as slamming on the brakes or jerking the steering wheel, which could potentially cause the vehicle to hit other vehicles, pedestrians, or objects on the side of the road.

Moreover, in certain weather conditions, such as when driving through waterlogged areas, an unexpected engine start can be catastrophic. If water enters the engine’s cylinders during startup, it can cause severe engine damage, known as hydrolock. This not only leaves the vehicle disabled but also poses a significant financial burden on the owner, as engine repairs in such cases can be extremely costly. Additionally, in some situations, the sudden engine start could cause the vehicle to stall in the middle of the water, putting the driver and passengers at risk of being stranded in a dangerous location.

V. Solutions and Suggestions

5.1 Temporary solutions for owners

If you find yourself in a situation where your BYD electric vehicle’s engine starts unexpectedly, there are several immediate steps you can take. First, try restarting the vehicle. Sometimes, a simple restart can reset the vehicle’s control systems and resolve any temporary glitches. To do this, safely pull over to the side of the road, turn off the vehicle completely (using the power – off button or key), and then wait for a few seconds before turning it back on.

Next, check the battery connection. Loose or corroded battery connections can cause electrical issues that may lead to unexpected engine startups. Open the hood of your vehicle and locate the battery. Inspect the cables connected to the battery terminals. Make sure they are tightly fastened and free from any signs of corrosion, such as a white or greenish – blue powdery substance. If you notice any corrosion, you can clean the terminals using a mixture of baking soda and water. Apply the mixture to the terminals with a brush, then rinse them with water and dry them thoroughly.

Another thing to consider is the vehicle’s settings. Review the settings related to the engine start – stop function, hybrid – electric mode transitions, and any other relevant settings in the vehicle’s infotainment system. Ensure that the settings are configured as you expect them to be. For example, if you prefer to drive in all – electric mode as much as possible, double – check that the mode settings have not been changed accidentally.

5.2 Long – term solutions

For BYD as a manufacturer, it is crucial to take this issue seriously and implement long – term solutions. One of the most effective ways is to release software patches. The company’s engineering team should conduct a thorough investigation into the root causes of the unexpected engine startups, whether it’s due to software bugs or incorrect OTA upgrade implementations. Once the issues are identified, they can develop and distribute software updates that correct the engine – start logic, fix any software glitches in the battery management system or the engine control unit, and ensure that the vehicle operates as intended.

In some cases, a recall for repair may be necessary. If the problem is found to be a hardware issue, such as faulty sensors or a malfunctioning ignition system, BYD should recall the affected vehicles and replace the defective components. This not only shows the company’s commitment to customer safety and satisfaction but also helps to restore confidence in their products.

Moreover, BYD should improve its quality control and testing procedures. Before releasing any new software updates or making changes to the vehicle’s systems, more rigorous testing should be carried out. This includes testing in various real – world scenarios, different environmental conditions, and with a wide range of vehicle usage patterns. By doing so, potential issues can be identified and resolved before they reach the customers.

5.3 Maintenance and inspection advice

Regular maintenance and inspection of your BYD electric vehicle are essential for preventing unexpected engine startups and ensuring the overall health of the vehicle. It is recommended to follow the manufacturer’s maintenance schedule strictly. This includes regular oil changes, even if your vehicle is primarily electric, as the engine still requires proper lubrication when it does run.

During maintenance visits to the dealership or a qualified mechanic, ask for a comprehensive check of the vehicle’s electrical system. The mechanic should inspect the battery, battery management system, all sensors, and the engine control unit. They can use diagnostic tools to detect any potential issues, such as abnormal electrical readings or software errors.

In addition, pay attention to the vehicle’s performance and any unusual signs. If you notice anything out of the ordinary, such as a strange noise, a change in fuel consumption, or an unexpected warning light on the dashboard, have the vehicle checked immediately. Early detection of problems can prevent them from escalating into more serious issues, including unexpected engine startups.

By following these solutions and suggestions, owners can better manage the situation when faced with unexpected engine startups, and BYD can take steps to improve the reliability and safety of their electric vehicles, ensuring a more pleasant and worry – free driving experience for all.

VI. Conclusion

6.1 Summary of key points

The unexpected engine startups in BYD electric vehicles are a complex issue with multiple potential causes. Battery – related problems, such as low voltage and BMS glitches, electronic control system malfunctions like sensor failures and ECU issues, mechanical system faults including ignition and fuel system problems, and software – related reasons such as OTA upgrade glitches and software bugs, all contribute to this phenomenon.

These unanticipated engine starts have a significant impact on vehicle performance, increasing fuel consumption, reducing energy efficiency, and causing excessive wear and tear on components. Moreover, they pose serious safety risks in various driving and parking situations. However, through a combination of temporary solutions for owners, long – term solutions from the manufacturer like software patches and recalls, and regular maintenance and inspection, the situation can be managed and potentially resolved.

6.2 Future outlook

It is hoped that BYD will take prompt and effective action to address this issue. By enhancing its quality control and testing procedures, the company can prevent similar problems from occurring in future vehicle models and software updates. As the electric vehicle market continues to grow, the reliability and safety of these vehicles are of utmost importance.

Owners are encouraged to remain vigilant and report any further instances of unexpected engine startups to BYD and relevant consumer protection platforms. This continuous feedback loop will help BYD improve its products and ensure that electric vehicle owners can enjoy a safe, efficient, and worry – free driving experience. With the right measures in place, BYD can overcome this challenge and continue to be a leading force in the global electric vehicle industry.