Nissan Altima: Key Light on Dash and the Car Won't Start

If your Nissan Altima suddenly won't start, and the only clue why is a key light on your dashboard, this article will help you understand what may be happening. Further, we shall suggest handy solutions to each of the causes mentioned. That's not all, we will also briefly discuss how you can prevent this problem from reoccurring once you have it fixed. 

Key warning light highlights

• Common reasons:key fob battery dead, 12V battery low, immobilizer issues
• How to fix:change the key fob battery, check the 12V battery, have the car inspected
• Possible consequences:car may refuse to start
• Priority level:High
• Can you drive?Yes, if it starts
• DIY repair:Possible
• Repair price range:$5-$350

What Does the Key Light on Your Dashboard Indicate?

Your Nissan intelligent key warning light is designed to warn you whenever there is a malfunction of your intelligent key system or electrical steering lock system. Whenever you switch on your ignition, the light should come illuminate for two seconds and then disappear. Should the light continue illuminating, something is not right with either your electrical steering lock system or the intelligent key system. 

Unfortunately, if this light comes on when your engine is switched off, your only option may be to tow the vehicle. This is because freeing your steering lock and starting your engine becomes very difficult. Depending on your preference, you can tow the vehicle to an authorized dealership or an experienced and trustworthy mechanic. 

Should the light come on while you are driving, it is advisable to visit a dealership or mechanic immediately. This will ensure your vehicle does not fail to start after you park it. Ignoring the light is a sure way to end up stranded. 

Reasons Your Nissan Altima Has a Key Light On The Dash and Fails to Start

As mentioned above, the only two systems that your key light symbol could be raising an alarm about are the intelligent key and steering lock systems. However, several aspects of these two systems could be causing the light to flare. Here are the most common.

1) Your Key Fob Battery is Dead

In most instances where a key light warning symbol appears on the dash of a Nissan Altima, a dead key fob battery is usually to blame. As your key fob ages, the battery loses its power and thus emits a much weaker signal. The problem will first manifest as a problem when unlocking and locking your doors. 

Eventually, the battery will become totally drained which will cause your intelligent key system to fail to recognize the key. Your ECU will display the warning sign to alert you of the low or dead battery. 

Solution 

Replace your key fob's battery. Use a screwdriver to remove the cover and insert the new battery. If replacing your battery does not solve the problem it is likely caused by one of the problems on this list.

2) Your Key Fob is Faulty 

Another likely culprit behind the key light warning symbol on your dashboard could be a physical or internal fault in the key fob. Especially if your key fob is old or is often subjected to unsuitable conditions e.g. being put in a pocket with keys and coins or being stored in a location where it may absorb moisture e.g. on a window sill. 

Exposure to moisture could cause your key fob's electrical circuit to short. Physical damage caused by keys or coins may cause physical damage by pressing keys out of position. The most common internal key fob fault is the development software problem e.g. programming bugs that prevent your Nissan Altima's antenna from detecting the key as usual. 

Solution 

If you have a spare key, try using it. Should your Nissan detect the spare fob but fail to detect your go-to key, there are two major possibilities. Your everyday key fob may have developed some of the physical or internal faults described above. Take your key to the dealership or locksmith to determine whether it can be salvaged. 

Often, the easiest and most effective solution is to replace the faulty key fob by having the dealership or locksmith program a new one. It is good practice to purchase an original Nissan branded key fob to avoid challenges with programming and detection by the antennae. 

Do not use your spare key for too long without making a copy. Remember that should anything happen to your spare key, the cost of making a new key from scratch will be much higher than copying from a spare. 

3) Your Nissan Altima's Antenna is Malfunctioning 

Your car is fitted with an antenna that scans for and senses the signal your key fob transmits. Only after the antenna detects your key fob's unique signal does the vehicle's computer allow the unlocking of doors and starting of the engine. 

Your Nissan Altima's red key light warning symbol and its failure to start may be caused by an antenna malfunction. Several Altima owners on Nissan forums online have complained about antenna malfunction issues coming out of left field and leaving them unable to enter or start their vehicles. 

If none of the other problems mentioned above are the cause of the red key light warning symbol, you may be dealing with a malfunctioning antenna that has suffered water damage or accelerated wear and tear over time. 

Solution 

A malfunctioning antenna is not a DIY problem. If you suspect that your antenna is the cause of the key light on the dashboard and failure to start, it is best to rely on the professionals. Have your Nissan Altima towed to the nearest dealership or reliable garage for accurate diagnosis and expert repairs. 

4) Your ECM or Immobilizer Has Failed

This is one of the rarest causes of the key light and dash and the vehicle's failure to start. Your Nissan Altima's immobilizer system ensures that car thieves cannot drive off in your car. The immobilizer system disables your Altima's engine whenever it detects an unrecognized or incorrect key. Should your immobilizer system malfunction, you will most certainly have a hard time getting your Altima to start. 

Your ECM (engine control module) is in charge of various aspects of engine performance. It relies on the immobilizer for the power-up of the ignition and starting system. Where either of these systems fail or malfunction, you will be unable to start your Altima and are likely to be presented with the key light warning symbol as a clue. 

Solution

This problem also calls for professional eyes and hands to solve it permanently. If you are looking for a temporary solution, or simply to confirm that the error is caused by the ECM or immobilizer, you could switch off your anti-theft system. This course of action is not recommended because should your car get nicked while the anti-theft system is turned off, your insurance company will not compensate for your loss. 

5) Your Steering Lock Control Unit is Faulty

Where the key light warning symbol on your dashboard is yellow, the most likely cause is a malfunction of the steering lock control unit. A fault in the system will cause your steering wheel to fail to complete its shutdown cycle. When this malfunction occurs, your car will fail to start and you will get a yellow key warning light as a clue. This problem was so prevalent that Nissan had to issue a recall of the affected vehicles and offer an extended warranty to replace the steering lock unit. 

Solution

This is yet another fix that is beyond most DIYers. If your Altima's failure to start has left you in a sticky situation, you can use this temporary fix. While pressing the start button and the brakes, tap on the steering lock control gently using a hammer. This should start your vehicle but do not forget that (unless you want to use a hammer every time you start the Altima) the real solution is replacing your steering lock control unit. 

How to Avoid the Key Light Warning System in Your Nissan Altima

After getting to the bottom of and solving the problem with your intelligent key system, it is wise to take small measures that guarantee you will not have trouble entering or starting your Altima in the future. Consider implementing these preventative measures:

• Do not expose your key fob to moisture or extreme temperature. Similarly, do not subject the fob to physical stress by placing it in pockets that have sharp or heavy objects like keys and coins.
• When programming new fobs, ensure you purchase an OEM key and have it programmed at the dealership.
• Ensure your Nissan Altima undergoes periodical service and maintenance checks as recommended in your owner's manual.
• Replace your key fob battery every three years to avoid the transmission of a weak signal that is undetectable to your antennae.

Conclusion

The key light on your Nissan Altima's dashboard could be caused by any of the problems listed above. Should you figure out how to start your car without solving the error, be sure to drive it to a licensed dealership or a certified and insured mechanic. Considering how security-sensitive key fobs are, it is always better to shell out a few extra dollars at a dealership than risk providing sketchy mechanics or locksmiths with the ability to copy your car keys.