Key takeaways
- A discharged 12V battery may prevent smart entry and other electrical systems from operating normally.
- Most Lexus vehicles include a mechanical back-up key that can be used to unlock the vehicle when electrical power is unavailable.
- Vehicles equipped with Lexus e-Latch include manual override mechanisms for door operation.
- The location and operation of manual door releases varies by model. View your vehicle owner’s manual here.
- If you’re concerned about battery condition, your Lexus retailer can carry out a complimentary battery inspection.
- The information in this article applies to Lexus models sold in the UK.
Introduction
Lexus vehicles are designed to provide a seamless ownership experience, with sophisticated technologies working intuitively in the background to enhance convenience and comfort. Like any modern vehicle, however, many of these systems rely on a 12V battery.
Should that battery become fully discharged, features such as smart entry and certain electronic door functions may become temporarily unavailable. To support drivers in these situations, Lexus vehicles incorporate alternative methods of entering and exiting the vehicle.
This guide explains the available options if your Lexus won’t unlock and highlights where to find further model-specific information.
Why won’t my Lexus unlock?
If your Lexus does not unlock when you approach it, the cause may be something straightforward, such as a depleted battery in the electronic key.
In some situations, however, a discharged 12V battery may prevent smart entry and other electrical systems from functioning as expected.
To help maintain access when electrical power is unavailable, Lexus vehicles incorporate alternative entry and exit methods that can be used when required.
What is smart entry?
Smart entry allows convenient access to compatible Lexus vehicles without removing the electronic key from a pocket or bag. Drivers should carry their electronic key with them whenever operating the vehicle.
When functioning normally, the system detects the presence of the authorised key via low-power radio signals and allows selected vehicle functions to be used automatically. If either the electronic key battery or the vehicle’s 12V battery becomes depleted, smart entry may not operate as intended.
Before assuming the vehicle’s 12V battery is discharged, it may be worth checking the following:
The electronic key battery
For vehicles equipped with smart entry and start, the battery within the electronic key typically lasts between one and two years, regardless of how frequently the key is used.
If the battery charge becomes low, an audible alert will sound and a warning message may be displayed within the vehicle.
The key is within operating range
In most Lexus vehicles, smart entry can operate when the electronic key is within approximately 0.7 metres (2.3 feet) of an exterior door handle.
Only the doors that detect the key can be operated.
Potential signal interference
The system’s performance may be affected by strong radio waves or electrical interference in the surrounding area.
Possible sources include:
- Television transmission towers
- Airports
- Large electronic displays
- Power stations
- Radio transmitters
Extended periods of inactivity
In some vehicles, if smart entry has not been used for 14 days or more, the vehicle may only unlock from the driver’s door. In this situation, press the button on the driver’s door handle or use the wireless remote control or mechanical key to unlock the vehicle.
In this situation, press the button on the driver’s door handle or use the wireless remote control or mechanical key to unlock the vehicle.
What is Lexus e-Latch?
Available on selected Lexus models, e-Latch is an electronic door-opening system designed to enhance both convenience and safety.
On the exterior, the doors have electric buttons providing easy, finger-tip operation with no need to pull a handle.
Inside, the system replaces a conventional interior door handle with an electronic switch located alongside the armrest within the door trim. e-Latch also operates in conjunction with Blind Spot Monitoring technologies to support Safe Exit Assist.
If an approaching vehicle or cyclist is detected from behind, the system can help reduce the risk of opening the door into their path.
How to enter your Lexus if the 12V battery is flat
Most Lexus electronic keys contain an integrated mechanical emergency key that can be used when the vehicle’s electrical systems are unavailable.
While the exact process differs between models, entry is typically achieved by:
- Removing the mechanical key from the electronic key.
- Locating the concealed lock cylinder on the driver’s door.
- Unlocking the vehicle manually.
The mechanical key can only be inserted in one orientation. If it does not fit into the lock cylinder, remove it, turn it over and try again.
This section of our ‘Know Your Lexus’ film shows how to remove your mechanical key and unlock your Lexus manually:
Once access has been gained, roadside assistance, battery charging or a jump-start procedure may be required depending on the cause of the issue.
Always refer to your Lexus owner’s manual for model-specific guidance.
How to exit your Lexus if electrical power is unavailable
Vehicles equipped with conventional mechanical interior door handles can continue to be opened as normal, even when the 12V battery is discharged.
As described above, selected Lexus models are fitted with the Lexus e-Latch system. To ensure occupants can still exit the vehicle if electrical power is unavailable, these vehicles also incorporate a manual override function.
To operate the manual release, pull the door opener switch towards you twice, in the same way you would operate a conventional interior door handle.
As the precise design and location of the mechanism can vary by model, owners are encouraged to familiarise themselves with the instructions provided in their vehicle handbook.
This section of our ‘Know Your Lexus’ film shows how manual operation of Lexus e-Latch works:
Smart entry and emergency door access by model
| Model | Smart entry available?* | e-Latch fitted?* | Manual entry method | Manual exit method |
| LBX | Premium Plus, Premium Plus Design, Takumi, Takumi Design | Yes | Mechanical key in fob | Pull door opener switch twice |
| UX | Premium, F Sport Design, F Sport Design Tech, F Sport, Takumi | No | Mechanical key in fob | Standard manual door release |
| NX | Urban, Premium, Premium Plus, F Sport, F Sport Takumi, Takumi | Premium, Premium Plus, F Sport, F Sport Takumi, Takumi | Mechanical key in fob | Pull door opener switch twice |
| RX | Premium, Premium Plus, F Sport Design, F Sport, F Sport Takumi, Takumi | Premium, Premium Plus, F Sport Design, F Sport, F Sport Takumi, Takumi | Mechanical key in fob | Pull door opener switch twice |
| RZ | Premium, Premium Plus, F Sport, F Sport Takumi, Takumi | Premium, Premium Plus, F Sport, F Sport Takumi, Takumi | Mechanical key in fob | Pull door opener switch twice |
| LM | LM, LM Takumi | LM, LM Takumi | Mechanical key in fob | Pull door opener switch twice |
*Availability correct at the time of publication but may vary according to model year, grade and specification.
What causes a 12V battery to discharge?
The 12V battery supports a range of vehicle systems and, like any battery, its condition can be influenced by factors including vehicle usage, driving patterns, battery age, environmental conditions and electrical demand.
Regularly undertaking very short journeys or leaving a vehicle unused for extended periods may affect battery charge levels over time.
If you have concerns regarding your battery’s performance, your Lexus retailer can provide further advice and support.
For additional information, read our guide to caring for your vehicle’s 12V battery.
Can Lexus check my 12V battery’s condition?
Yes. If you have concerns about the condition or performance of your vehicle’s 12V battery, your local Lexus retailer can carry out a complimentary battery health inspection and advise on any recommended next steps.
Where can I find more information?
Owner’s manuals and user guides for current Lexus models can be accessed through the Lexus ownership section online. View Lexus owner resources here.
Frequently asked questions
Can I still access my Lexus if the 12V battery is discharged?
In many cases, yes. Most Lexus electronic keys incorporate a mechanical emergency key that can be used if smart entry is unavailable.
Does a discharged 12V battery prevent smart entry from working?
A fully discharged 12V battery may prevent smart entry and other electrical systems from operating normally.
Can I open the doors if electrical power is unavailable?
Vehicles equipped with Lexus e-Latch incorporate manual override mechanisms that allow doors to be opened when electrical power is unavailable.
Where is the manual interior door release located?
The location varies according to model. Please refer to your vehicle’s owner’s manual for specific instructions.
Does a discharged 12V battery indicate a problem with the hybrid battery?
Not necessarily. The 12V battery and hybrid battery perform different functions within the vehicle.
Who should I contact if I need assistance?
If you’re unable to access or start your vehicle, contact Lexus Roadside Assistance if you are a member, your Lexus retailer or Lexus Customer Relations for support. You can also use the Lexus retailer locator to find your nearest centre.
I had the battery changed on my NX last year, just over 12 months old. I tried to follow the instructions on line to open the door from the outside, I couldn’t remove the cap for the key, broke a loyalty card in the process. Fortunately, the car was at home so I eventually removed it using a metal blade. I followed the instructions but couldn’t open the door, so called Lexus assistance. It would appear the instructions relate to a LHD car as the key had to be turned the opposite way. The battery was totally flat and put on charge. Took it to the dealership who told me I wasn’t driving it enough. They put the battery on charge and I drove home, 10 miles. The car wouldn’t start again three days later. The dealership then changed the battery. Looking at the battery it is a very small capacity for the car with all its systems and it’s not surprising that it needs regular topping up. I would be very anxious if going away on holiday for a couple of weeks or more, as I wouldn’t have the opportunity to charge it or maybe open the door lock, following the previous experience. It would have to be a call to Lexus Assistance. The battery capacity needs to be increased.
Morning Mike,
We’re sorry to hear about your experience and the disappointment and inconvenience this caused.
If you have any further issues with your Lexus NX in the future, please don’t hesitate to get in touch with your local Lexus Centre.
Thank you.
We were advised to carry a booster jump start battery to cover any such issues, eg if we park at the airport for over 2 weeks, however, how do we access the boot to get this if the battery does goes flat?!
Morning David,
In this instance, when leaving your car for an extended period of time, it may be useful to leave the accessory in the front of the car so it can be easily accessed when entering the car with the mechanical key, in the case of a flat battery.
Thank you.
I wish you could have told me of the situation with the 12 volt battery before I purchased the vehicle then I would’ve have purchased the vehicle.I am very nervous about leaving the vehicle for a week or two and not driving it.You must have received some disturbing information from owners to have sent this information out to all Lexus owners.
Morning Colin,
We apologise for the concern this has raised.
With the wide choice of powertrains available today, our retailers understand the importance of discussing a customer’s driving patterns and expected vehicle usage before recommending a particular vehicle. Toyota and Lexus have sold hybrid vehicles in the UK for more than 25 years, with over one million hybrid vehicles sold. We do not specify a minimum annual mileage requirement for our hybrid vehicles. As with any vehicle, 12v battery condition and lifespan are influenced by a variety of factors including driving patterns, journey types, vehicle usage, environmental conditions and battery age.
Read more here and pick up some tips that, if followed, can help ensure your Lexus remains in tip-top condition: https://mag.lexus.co.uk/12v-battery-care/
Thank you.
It’s very unfortunate that you have to explain to Lexus owners what to do when their battery goes flat through no fault of their own. Not everyone uses their car every day and it shouldn’t be a problem if you don’t do this.
Lexus is a luxury car brand, and to have this battery problem is not acceptable.
Great content and really helpful guides
Thankyou for the helpful summary of how to access the vehicle in the event of a flat battery. However, this does not provide a full solution as the 12v battery needs to be charged and a description of how to do this would be helpful. Ultimately I would like to see a larger capacity 12v battery or a facility to charge the 12v battery in an emergency from the traction battery. Another solution may be to incorporate solar panels so that the 12v battery is continuously charged to avoid going flat if left at an airport for 30 days.
if, after an accident, the car is on fire and I am unconscious, how can the first person at the scene open the doors if the 12V system is no longer functioning? They won’t have the mechanical key available to them will they
Morning Barry,
Thank you for getting in touch.
First responders in this case would have to treat the vehicle like any other severe accident where a door can’t be opened due to extensive damage. If the vehicle was on fire or the door was damaged to an extent that the door can not be opened mechanically, then a window would need to be smashed in order to gain entry.
When our vehicles detect that an accident has occurred, or the pyrotechnics system has been deployed, the doors are automatically unlocked. Needless to say that our vehicles are fully compliant with all vehicle safety regulations.
Thank you.
Hello. This information is very helpful, thank you. My LBX is now 4 months old and I regularly leave it unused for between 2 and 6 weeks whilst I’m abroad.. Although Lexus Link sends me a message after around 12 days that the car may not start, so far, it always has. Will there come a time when the car will not start (depleted battery) or is this worrying message just precautionary? If the car is designed to fail after a few weeks of inactivity, maybe it’s not the right car for me – as I live abroad for up to 90 in 180 days each year. Your advice would be appreciated.
Morning Nick,
Thank you for your comment.
The 12v auxiliary battery is a quietly essential component of your vehicle’s electrical architecture. It provides the primary source of power for all low-voltage systems, including lighting, climate control, audio features and, where fitted, the starter motor. While modern vehicles incorporate significantly more technology than those of previous generations, the fundamental principle remains unchanged: the 12v battery is replenished through the operation of the powertrain.
Read more here and pick up some tips that, if followed, can help ensure your Lexus remains in tip-top condition: https://mag.lexus.co.uk/12v-battery-care/
Thank you.
Excellent
A very useful email. Thank you Lexus.