Lexus NX Won’t Start – What Could Be Wrong?

If your Lexus NX won't start, it can put a wrench in your plans. So what could be the culprit of this problem? We have taken the time to help you troubleshoot this issue in this article.

If your Lexus NX doesn't start, it could be due to the following issues:

  • Dead Battery
  • Corroded Battery Terminals
  • Loose Battery Cables
  • Dead Key Fob Battery
  • Faulty Alternator
  • Bad Fuel Pump
  • Worn Spark Plugs
  • Faulty Starter Relay
  • Bad Starter Solenoid
  • Bad Starter Motor
  • Faulty ECU
  • Malfunctioning Immobilizer System
  • Bad Ignition Switch
  • Clogged Fuel Filters
  • Bad Fuel Injectors

As you can see, there are several reasons as to why your Lexus NX won't start. But, not to worry, because we will discuss each in this article and how to troubleshoot them. In addition, we will discuss and answer other frequently asked questions about the Lexus NX, so read on!

fire color Lexus NX 300h on big Vossen wheels parked in evening cloudy day, Lexus NX Won't Start - What Could Be Wrong?

Lexus NX Won't Start - What Could Be Wrong?

As discussed above, there are several reasons why your Lexus NX won't start. Now we will discuss each one and how to troubleshoot them.

Dead Battery

Accumulator charging. Hands and terminals. Car repair. Service station.

If your battery is dead and won't hold a charge, you may need a replacement. How do you know if the battery is dead? Well, some common signs consist of:

  • The car cranks several times before it starts.
  • The car makes a clicking sound when you turn the key to start it.
  • Headlights won't turn on.

To confirm that the battery is dead, we recommend measuring its voltage using a multimeter. Then, try jumpstarting the car with another car or a jumpstarter. If it doesn't start, the battery is most likely dead and will need to be replaced at an automotive store.

Corroded Battery Terminals

Next, we want to determine if the issue is with the terminals. So the first thing you will want to do is check for corrosion around terminals.

If there is no corrosion present, move on to the next section of this article. Take a wire brush and carefully scrub the corroded terminals if corrosion is present.

You will want to make sure you clean them until they look new. After this, we recommend applying anti-corrosion spray or grease on the terminals and cleaning metal parts near the battery with a wire brush.

Loose Battery Cables

Another thing you may want to check is the battery cables. The terminals on these cables can loosen over time and need tightening. Again, we recommend using a wrench to tighten them. If they still pop off and need replacing, we recommend buying new ones and installing them yourself or doing this at an automotive store.

Dead Key Fob Battery

Broken or damaged remote key fob and new vehicle key on black dark grey background

One of the most common reasons your Lexus NX won't start is that the battery in your key fob is dead. If this is the case, you should replace it with a new one from an automotive store and install it yourself or have it installed at an automotive store.

Faulty Alternator

If the alternator is bad, it will not produce enough voltage to start the car. Some common symptoms of a bad alternator are:

  • The battery light illuminates the dashboard.
  • As a result, the car struggles to start.
  • Also, the headlights get dimmer when the engine is running.

We recommend measuring the voltage with a multimeter to determine if the alternator is bad. If it is below 12 volts, it is most likely bad and will need to be replaced.

Bad Fuel Pump

If you turn the key to start your Lexus NX and it cranks but doesn't start, there is a chance that the fuel pump isn't working. Likewise, if you hear a whining noise when you try to start the car, that is a sign of a failing fuel pump.

Worn Spark Plugs

When you start your Lexus NX, and it cranks but doesn't start, there may be a problem with the spark plugs. If these are faulty, they will need replacement. To see how to do this yourself, check out our article on replacing them.

Faulty Starter Relay

The starter relay may be bad if your Lexus NX cranks but doesn't start. The starter relay is an electrical component that sends a signal to inform it when to turn on. The starter relay will make a clicking noise if it is faulty and must be replaced.

Bad Starter Solenoid

Another cause of your Lexus NX not starting is the starter solenoid. This component manages power to the starter and makes a clicking noise if it is faulty. Again, you will have to have a mechanic check between the relay and the solenoid to see which is at fault.

Bad Starter Motor

If your Lexus NX cranks but doesn't start, the starter motor may be faulty. The starter motor is responsible for turning the engine, making it hard to turn over. If the starter motor is bad, you will need a mechanic to replace it and check between the relay and solenoid.

Faulty ECU

If your Lexus NX doesn't start, the ECU (Electronic Control Unit) or another computer component may be the problem.

To check, you will want to remove the ECU and bring it to an automotive store where they can test it. If there is a problem, they will need to replace it, which requires special equipment.

Malfunctioning Immobilizer System

If your Lexus NX won't start, there may be a malfunction with the immobilizer system. This anti-theft deterrent prevents the car from starting unless it has the correct key fob programmed to it.

In this case, you may need to have the key reprogrammed. You can also try disconnecting your battery cables for 30 seconds to a minute and reattaching them. However, doing this may reset the immobilizer system.

Bad Ignition Switch

If your Lexus NX has starting issues, the ignition switch may be bad. This component makes sure that all of the controls in your car are turned off, which means it has to function as expected every time you try to start your car. If this is faulty, you will need a mechanic to replace it.

Clogged Fuel Filter

The fuel filter may be clogged if your Lexus NX won't start. When this happens, remove the fuel filter and replace it. If this doesn't fix the problem, you will need your fuel injectors cleaned at an automotive store like Jiffy Lube.

Bad Fuel Injectors

When your Lexus NX won't start, the fuel injectors may be at fault. Dirty fuel injectors can cause this problem and might only need to be cleaned. However, if the fuel injectors are bad, they will need to be replaced.

Lexus NX at the international press launch

How Do You Start a Lexus NX Without a Key Fob?

If your key fob battery has died, you can still start your Lexus NX. To do so, follow these steps:

  1. First, you will need to remove the key inside the key fob.
  2. Next, manually unlock the door by placing the key into the key slot in the door handle.
  3. Then, sitting in the driver's seat, put your foot on the brake, press the push to start button with the key fob itself.
  4. The computer will recognize that the key fob is in the car and start the vehicle.
  5. Once the car starts, you will need to go to a Lexus dealer or automotive store to get a new key fob battery.

How Do You Jumpstart a Lexus NX300?

To jumpstart a Lexus NX300, follow these steps:

  1. First, you will need to remove the key from the ignition and open the hood.
  2. Next, find the battery.
  3. Clip one of the red clips to the positive cable.
  4. Clip one of the black clips to the negative cable.
  5. Connect the other end of the red clip to another vehicle's positive terminal, and connect the other end of the black clip to another car's negative post.
  6. Turn on the donor vehicle.
  7. Now, attempt starting the Lexus 300. If it doesn't start the first time, resecure the jumpstart cables and try again.
  8. Once the vehicle starts, let it run for 10-15 minutes to give the battery time to recharge.

Jump Starting a Car Battery

How Do I Reset My Lexus?

To reset a Lexus, you will need to follow these steps:

  1. First, turn the Lexus ignition to the "ON" position.
  2. Next, switch the odometer set to "Trip A."
  3. Now, turn the ignition to the "OFF" position.
  4. Simultaneously, hold down the "TRIP RESET" button while turning the ignition to the "ON" position.
  5. Next, hold the "TRIP RESET" button until the maintenance required light flashes and turns off.
  6. Once the maintenance required light turns off, turn the ignition switch to the off position.
  7. Lastly, turn the ignition back to the "ON" position to confirm the light is turned off. If it doesn't, repeat the steps.

Final Thoughts

 A Lexus NX 300h F-Sport crossover hybrid car

Lexus is known to make good vehicles, but you will have problems from time to time like any vehicle. If you have issues getting your Lexus NX started, start with the basics, such as checking the battery, battery cables, battery terminals, and key fob battery. From there, you may need to contact a Lexus dealer or a qualified mechanic for further assistance.

For more maintenance guide articles, check out our website:

Lexus Won't Start But Has Power – What Could Be Wrong?

Crankshaft Not Spinning Freely – What Could Be Wrong?

Car Sounds Like Helicopter—What Could Be Wrong?

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