AT Check Light On Nissan Altima – What Are The Problems

The automatic transmission (AT) is a crucial system of your Nissan Altima, responsible for transferring power from the engine to the wheels.

If the AT check light on Nissan Altima illuminates, it could indicate a problem with the transmission system.

Ignoring this warning signal might equal costly repairs and catastrophic harm to your car.

This article will explore the possible reasons why your AT check light is on and its associated problems.

What Is The AT Check Light On Nissan Altima?

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AT Check Light On Nissan Altima

What does AT check light mean on a Nissan Altima? 

The AT check light on a Nissan Altima is a warning light that signals a potential issue with the vehicle’s automatic transmission system due to low fluid, overheating, or a failure in related parts like a valve body. (I will dive deeper into this later)

The automatic transmission system in a Nissan Altima is a complex network of gears, fluid passages, and electronic sensors that work together to ensure smooth and efficient vehicle performance.

It’s responsible for transmitting the power generated by the engine to the car’s wheels, allowing it to move forward or backward.

When this error code shows up on the dashboard, it’s a sign that the transmission control module (TCM) has detected a fault in the system.

Such a case could create transmission issues and motor damage if left unaddressed.

What Can Cause The AT Light To Come On?

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Why Is At Light To Come On

Once the 2005 Nissan Altima AT check light goes on, it may indicate several problems, including:

Low Transmission Fluid

The Nissan Altima’s AT check light may turn on due to low transmission fluid.

As it provides lubrication, cools the transmission, and aids in power transmission, this fluid is significant for the system to work properly.

When the AT check light comes on, the driver should immediately check the transmission fluid level and add more if needed.

But there was a time when my fluid level was consistently low, and the auto repair mechanic detected a vacuum leak.

So once the shortage is excessive, bring it to a repair shop for a check-up.

Overheating Transmission

The Automatic transmission fluid (ATF) is an advanced safety feature that helps regulate the transmission temperature.

Some major signs can result from overheating or other faulty emissions that I have experienced, including:

  • Unusual noises
  • Damage to ignition coils
  • Faulty head gasket 
  • Dirty spark plug
  • Vacuum leak
  • Faulty oxygen sensor
  • Problems with the cylinder engine
  • A low level of transmission fluid
  • A faulty cooling system
  • Continuous hard driving

I usually take a basic diagnostic by pulling to a safe location, turning off the engine, and letting the transmission cool down for some time.

Checking and refilling the ATF to the recommended oil level can also help prevent overheating.

Shift Interlock Malfunctioning

Shift interlock is an option that prevents the gear selector from being shifted out of “Park” till the brake pedal is pushed in vehicles with automatic transmissions.

A malfunctioning shift interlock can illuminate the AT check light in the Nissan Altima.

This common issue can happen if the shift interlock solenoid fails or if there is any underlying issue with the brake light switch that infotainment controls the solenoid.

Once the part has a poor performance, the shifter may not move from “Park,” which can be a safety concern.

Sometimes, I even notice the brake lights don’t operate due to the same issue, making it difficult for other drivers to know when my car is slowing down or stopping.

Valve Body Failure

The valve body is a crucial component of the automatic transmission system.

It performs an assortment of functions, like regulating hydraulic pressure and directing fluid flow to the appropriate gears.

If the valve body is at fault, the vehicle will appear in trouble codes, and the transmission will slip, shift erratically or not at all, and trigger the problem of steady check engine light on the dashboard.

Also, a failed valve body can stem from wear and tear over time, clogged passages due to debris or sediment in the transmission fluid, defective spark plugs, bad mass airflow sensors, or electrical issues.

I could repair the valve body by replacing damaged components. But I always recommend a complete replacement by a professional mechanic with a diagnostic tool in severe cases.

Broken Torque Converter

Several things, including overheating, worn spark plugs, engine misfire, and mechanical failure, can cause a faulty torque converter.

It may be necessary to replace the torque converter if it malfunctions, which is expensive.

Any faulty sensor must be fixed as soon as possible to stop further harm to the transmission. What do the warning lights on a Nissan Altima mean? 

If the Nissan Altima’s check engine light codes are activated, a diagnostic test can assist in identifying whether the torque converter is to blame.

Electronic Control Unit/Computer Malfunction

The car’s onboard computer system is in charge of a mixture of functions and alerting the driver of any problems.

If there are electrical issues with the sensors or wiring, the computer may falsely detect a problem and trigger the warning light.

Additionally, a malfunctioning electronic control module may fail to detect an actual problem with the transmission system, bad fuel, or automobile battery, causing further damage if left untreated.

It’s important to inspect the computer control system by basic repair procedures and diagnose by a professional auto parts store to determine the source of the abundant damage accurately.


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Question Of Check Light On Nissan Altima

Can You Drive With Automatic Transaxle Light On?


It is not recommended to drive with the automatic transaxle (AT) check engine warning light on, as it hints at a problem with the transmission system.

Continuing to navigate with the check engine light warning could leave further damage to the transmission or other components of the vehicle.

It is best to have the vehicle inspected by an experienced professional for onboard diagnostics and repair the majority of car issues.

Is It OK To Drive With Check Engine Light?

No. Driving with the check engine light on is not recommended because there is a hidden problem with the engine or emissions system.

Continuing to drive with this complex issue may increase the average repair cost.

In addition, driving with a check engine light trouble can cause your vehicle to fail an emissions test, which can result in fines or other penalties depending on where you live.

How Do You Check Transmission Fluid Levels?

Locate the transmission fluid dipstick, remove it, and give it a good cleaning before checking the transmission fluid levels in your car.

Check the fluid level after re-inserting the dipstick and detaching it.

Remember to check the fluid level while the engine runs and the transmission is parked or neutral. The color of the fluid can also indicate the health of the transmission.

If the fluid is low or has a burnt smell or unusual color, it may be time to have your vehicle serviced by the nearest mechanic.


If the AT check light on Nissan Altima appears, diagnosing and repairing it immediately is important to avoid dangerous issues to your car.

The reasons for the AT check light being illuminated can vary from a simple minor issue to a more serious transmission problem.

Regular maintenance and following expert advice in a repair shop for vehicle inspections can help prevent these issues from arising.

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