Limp Mode in a Car: Everything You Need to Know

By Russ Heaps 04/24/2023 12:00pm

2023 limp mode in a car.


Quick Facts About Limp Mode

  • Your car enters limp mode as a way to protect itself from a failed or faulty system and prevent it from damaging other components.
  • Detecting the cause of a limp mode activation often requires a trained technician to diagnose the car’s computer system.
  • Eliminating the cause of a limp mode activation may be inexpensive and as easy as topping off the transmission fluid. 

Most newer cars are intelligent enough to protect themselves from excessive damage when certain systems run amuck. Once one of those systems begins malfunctioning, it sends an alarm to the car’s computer network. It reduces the vehicle’s power and speed to prevent further harm. This effort is known as “limp mode.”

We will explain limp mode, list some of its causes, symptoms of your car in this state, and a few preventive measures. To skip ahead, use the links below.


What Is Limp Mode?

A car’s limp mode is a security feature that kicks in when the vehicle’s computer network detects an issue with one of the critical systems. Also called “limp home mode,” the feature activates to prevent damage to your car and its components. It accomplishes this by slowing the car through the transmission, throttle control, or electronic control unit.

Limp mode reduces power and turns off things like your air conditioning, minimizing further harm while allowing you to get home, to a car service center, or simply out of the flow of traffic.

How Serious Is Limp Mode?

Limp mode is as serious as the issue which activates it. In other words, it may be severe or as easy to solve as a low transmission fluid level. Consequently, until you know which it is, your default reaction should be to take it very seriously. This is especially true if your car repeatedly goes into limp mode.

What Are the Typical Causes of Limp Mode?

Any number of issues can trigger limp mode. Among the most common:

  • Damaged wiring – Bad wiring or a loose connection inhibits or prevents the transmission of an electric signal.
  • Overheating – A hike in engine temperature above normal levels is often a call for help, usually indicating an issue with the cooling system.
  • Sensor malfunction – Today’s cars have many sensors monitoring the vehicle’s many systems and components. A car’s computer network reacts to a defective or failed sensor as it would if the system the sensor monitors failed.
  • Low fluid level – Transmission fluid, coolant, or engine oil dropping below a certain level.
  • Transmission issues – Problems like a failing clutch or a bad transmission solenoid.
  • Mass airflow sensor – A dirty or failed mass airflow sensor may not be accurately monitoring the flow and temperature of the air entering the engine.
  • Misfiring engine – Stalling while idling, severe shaking during acceleration, uneven acceleration, or black smoke from the exhaust are signs of a misfiring engine. Dirty or worn spark plugs may be the issue causing the misfiring.

What Are Limp Mode Symptoms and Signs?

Limp mode is a self-preservation function to protect your car. However, depending on where or when it activates, it can have the opposite effect. A sudden slowing in the middle of speeding freeway traffic can be downright frightening. Moreover, creeping along well below the speed limit on a busy street or highway can be dangerous and stressful.

If you’ve never experienced a limp-mode event, when it does happen, you may not recognize it for what it is. Here are some signs your car may be in limp mode:

  • Check-engine light – When the check-engine warning light on the instrument panel pops on, it can be triggered by anything from a catalytic converter issue to a loose or missing fuel-filler cap. Sadly, most drivers ignore the warning unless the car shows obvious evidence of a problem. However, if the car has slowed in conjunction with the check-engine light illuminating, the odds are the vehicle is in limp mode.
  • Transmission won’t shift – If your car’s automatic transmission is stuck in one gear,  often second or third, it very well could be a limp mode activation. It prevents a car from accelerating quickly from a stop and limits the speed once moving.
  • Limited rpm – Typically, a car’s limp mode will limit the engine’s rpm (revolutions per minute) to somewhere between 2,000 and 3,000. This has the added effect of limiting the speed to around 35 miles per hour.
  • Loss of systems – Because overheating is often the culprit in activation, limp mode may shut down systems, such as air conditioning, to lighten the load on the engine.

How to Get a Car Out of Limp Mode

You should treat a limp mode activation as an alarm that your car faces a serious problem. Overriding or bypassing limp mode could lead to an even more serious issue, requiring expensive repairs. If your check-engine warning light is on and limp mode has engaged, the issue requires an on-board diagnosis of your car’s computer system.

If you have an OBD-II scanner, you can run the diagnostic yourself. Otherwise, you should immediately take your car to a trained technician. You can learn more about the diagnostic process at Kelley Blue Book’s Service Advisor. Having said that, there are a few steps you can take in the meantime.

3 Steps to Escape Limp Mode

Turn off the engine – Find a safe place to exit the flow of traffic and turn off the engine. Wait at least 60 seconds and restart the engine. As with rebooting a computer, restarting the engine may be enough to get the engine to perform normally. If the issue is overheating and you are close enough to home or a repair center, your car may operate normally long enough to get you there. However, the chance of limp mode reactivating as soon as the engine gets hot again is likely. If a transmission issue caused your car to go into limp mode, you may have trouble getting it out of Park and into Drive once it’s restarted.

Check fluid levels – Low engine oil, transmission fluid, or coolant levels can sometimes trigger limp mode. Check the levels and top off if necessary.

Dirty air filter – A dirty air filter will prevent the smooth flow of fresh air into the engine. Inspect your engine air filter. If it appears dirty, replace it.

Preventing Car Limp Mode

The best prevention of limp mode is following the carmaker’s regular maintenance schedule for your car. Regular maintenance won’t prevent every cause triggering limp mode, but it will catch many causes before any damage is done. Regular engine tune-ups will ensure all the components are healthy and operating properly.