What to do when a car is in accessory mode?
When a car is in accessory mode, it means the vehicle's electrical system is powered on, but the engine is not running. This can happen if you accidentally leave the key in the ignition or if you intentionally put the car in accessory mode. In either case, there are a few important steps you should take to ensure your car's battery doesn't drain and to avoid any potential issues.
Understanding Accessory Mode
Accessory mode is a feature in most modern cars that allows you to use certain electrical components, like the radio or infotainment system, without the engine running. This is useful when you need to listen to music or use your car's features without draining the battery by keeping the engine on. However, if you leave the car in accessory mode for an extended period, it can cause the battery to die, leaving you stranded.
Steps to Take When a Car is in Accessory Mode
- Identify the Accessory Mode: Look for indicators on your dashboard or in your car's manual to confirm that the vehicle is in accessory mode. This is usually indicated by a light or symbol on the dashboard.
- Turn Off Electrical Devices: If you notice your car is in accessory mode, turn off any electrical devices you were using, such as the radio, climate control, or infotainment system. This will help conserve the battery's charge.
- Start the Engine: If you don't need to use the car's features and the battery is still charged, start the engine to return the car to normal operation. This will ensure the battery doesn't drain while the car is not in use.
- Remove the Key: If you accidentally left the key in the ignition, remove it to prevent the car from staying in accessory mode and draining the battery.
- Monitor the Battery: If you need to leave the car in accessory mode for an extended period, periodically check the battery level to ensure it doesn't become too low. You may need to jump-start the car or replace the battery if it's drained.
By following these steps, you can quickly address a car in accessory mode and prevent any potential issues with the battery or electrical system.
How do I turn my car off accessory mode?
To exit accessory mode, press the engine start/stop button again without your foot on the brake pedal. If the car won't turn off, ensure the vehicle is in park, try starting the engine and then immediately turning it off, or check your key fob battery.
Step-by-step guide to exit accessory mode
This video demonstrates how to turn off accessory mode: 1mTechnical EvolutionYouTube · May 31, 2025
- Press the start button again: With the car in accessory mode, simply press the engine start/stop button one more time. Your foot should not be on the brake pedal.
- Check the sequence: In many cars, accessory mode is the first "on" position. Pressing the button again cycles to "ON" (second press), and then a third press cycles to "OFF".
Troubleshooting if the car won't turn off
- Ensure the vehicle is in Park: The car will not turn off if it is not in park. Shift to park and try again.
- Start the engine and then turn it off: If a direct shutdown doesn't work, try pressing the brake pedal and starting the engine. Once the engine is running, press the start/stop button to turn it off completely.
- Check the key fob: A weak or dead key fob battery can sometimes prevent the car from shutting off. Replace the battery if it's low.
- Restart the system: A temporary software glitch might be causing the issue. Try disconnecting the 12V battery for a few minutes to reset the car's computer.
- Inspect the ignition switch: If the problem persists, there may be a hardware issue with the ignition switch. This would require professional diagnosis.
How long can a car last in accessory mode?
A car can last anywhere from a few hours to over 10 hours in accessory mode, but this depends heavily on battery condition and which accessories are used. A car with a healthy battery and only the radio on might last 10-12 hours, while using power-intensive accessories like climate control or aftermarket sound systems can drain the battery much faster, potentially within an hour. To extend the time, avoid using power-hungry electronics or start the engine every couple of hours to recharge the battery.
Factors that influence battery life in accessory mode
- Battery condition: A new battery in good condition will last much longer than an older one.
- Accessory usage: Using only the radio is far less draining than using fans, heated seats, or powerful stereos.
- Loudness: Playing music at a very high volume increases power consumption.
- Temperature: Cold weather can reduce battery performance.
- Vehicle specifics: Some cars have built-in timers to automatically shut off accessories after a set period to prevent battery drain.
How to estimate how long your car will last
- For a short period: A few minutes should be fine, as many cars automatically shut off most accessories after about 10-15 minutes.
- For a longer period: If you only need to run the radio, you might get several hours, but be prepared to drive for at least 20 minutes at higher speeds to fully recharge the battery if needed.
- To be safe: It's best to limit time in accessory mode to two hours or less, especially if using many accessories, and to avoid draining the battery to a point where you need a jump start.
Why is my car in accessory mode?
Your car is likely in accessory mode because you may have accidentally pushed the start/stop button twice, the key fob battery is low, or a faulty component like the ignition switch, brake pedal switch, or a weak battery is preventing it from starting. This mode powers accessories like the radio and windows without running the engine, but a persistent accessory mode with a failed start can indicate a problem that needs attention.
Common causes and solutions
This video explains the function of accessory mode: 22sHyundai of MuskokaYouTube · Oct 4, 2024
- Accidental double-press: You may have pressed the start/stop button once too many times while turning the car off, or pushed it with a shaky hand.
- Solution: Try pressing the button again to turn it off completely, or hold it to start the engine.
- Low key fob battery: A weak battery in the key fob can prevent the car from recognizing it, leading to a no-start situation.
- Solution: Try replacing the key fob battery. You can also check your car's manual for instructions on how to start the car in a pinch, like holding the fob against the start button.
- Weak or dying battery: A battery with a bad cell or a charging system issue can prevent the car from starting and may cause it to get stuck in accessory mode.
- Solution: Have your battery and charging system tested. Many auto parts stores can do this for free. If the battery is bad, replacing it should fix the problem.
- Faulty sensors or switches: Problems with the clutch pedal switch (in a manual car) or the brake pedal switch (in an automatic) can prevent the car from knowing it is safe to start.
- Solution: Make sure you are pressing the brake pedal firmly and try the start procedure again. For manual transmissions, ensure the clutch is fully depressed.
- Ignition switch or starter issues: Wear and tear on the ignition switch or a faulty starter relay can cause the car to get stuck in accessory mode.
- Solution: If the simpler steps don't work, the ignition switch or starter relay may need to be replaced.
If the problem persists
If these steps don't solve the issue, it is best to have a mechanic or dealership diagnose the problem. They can check for electrical faults, immobilizer system issues, or other problems that may be causing the car to get stuck in accessory mode.
Can I drive my car if it says engine power reduced?
You can drive a short distance to a repair shop, but it is not recommended to drive for long distances. The "engine power reduced" message means the car is in a protective "limp mode" to prevent further damage, which can be unsafe, especially on highways, and could lead to more expensive repairs. It's best to pull over when it's safe, turn off the engine, and have the car towed to a mechanic for diagnosis and repair.
Why you should avoid driving long distances
- Risk of further damage: Continued driving can worsen the underlying problem and lead to more expensive repairs.
- Safety concerns: The car will have limited acceleration and speed, which can be dangerous on busy roads or highways.
- Sudden failure: The car could stop running completely, leaving you stranded in an unsafe location.
What to do immediately
- Find a safe place: Pull over to the side of the road as soon as you can do so safely.
- Turn off the engine: This allows the system to cool down and can sometimes temporarily reset the mode.
- Assess the situation: If the message disappears after restarting, you may be able to drive a short distance to a mechanic. If it reappears, or if you are in a dangerous spot, do not drive further.
- Call for professional help: Contact a tow truck to get your car to a repair shop for a professional diagnosis and fix.
