Register Now


Lost Password

Lost your password? Please enter your email address. You will receive a link and will create a new password via email.


Register Now

Welcome to Ask A Master Mechanic. Please register to get fast help with your vehicle for free!

What is Limp Mode And How To Fix It?

What is Limp Mode And How To Fix It?

What is Limp Mode and how to fix it?


In this article, I will discuss a very common problem that I get a lot of questions about. I’m talking about the famous problem “Limp Mode”.

Some common questions I get from my customers is:

My car lost all power and engine light is flashing

My car is slow and dont shift out of 3rd gear

With this subject, there could be a lot of different scenarios depending on the car brand model and engine.


A possible scenario:

You are driving on the highway and suddenly the transmission is shifting down to 3rd gear and put an rpm limit at max 2500 rpm. You feel that your engine seems very slow. Your check engine light is flashing on the dashboard.
That’s exactly what could happen when the car is going into Limp Mode.

But why does that happen and how expensive will it be to fix? You may think.

In this article, I will teach you everything about limp home mode, What it is and why it does happen.



limp mode



What is Limp mode?


Limp mode is a state when you got limited functions from your engine control unit and transmission control unit.

Some common characteristics could be:

  • Reduced Engine Power
  • RPM Limit Lowered
  • Transmission is “stuck” in a gear
  • Check Engine light/Half engine light is flashing

It is depending a lot of what brand model and engine you have. There are many types of limp modes depending on how the manufacturer designed it.

p0420 code fix




What causes Limp mode?

The engine is set into limp mode when the car has detected a fault with the engine or transmission.

It’s a security function

The engine control unit is reducing the power and limit a lot of functions so you could drive your car to the closest workshop without destroying your engine.

The most common causes are

  • Electrical problems
  • Turbo boost problem
  • Electrical Transmission fault
  • Electric throttle valve problem
  • Sensor faults

That is only the most common causes and you should not use that list to start replacing parts without doing some real troubleshooting.

When the engine is getting wrong values from a sensor is a normal case.

What the engine control unit is doing with limp mode is using some calculated values out of other parameters which it think would be correct. In that case, the engine control unit will limit the functions because it’s not sure that it uses the real values.


limp mode




How do I fix the Limp mode?


To fix the limp mode, the first stage you have to do is to read the trouble code memory. When the car is going into limp mode it will have a stored trouble code inside either the engine control unit or the transmission control unit.

You can either read the trouble codes from home with a cheaper DTC code tool or you can drive to a workshop which probably will have better diagnostic tools to make a better troubleshooting.

If you want to read the trouble codes at home I would recommend this tool.

FOXWELL Obd Scanner Universal

FOXWELL Obd Scanner Universal This car scanner can read and erase DTC (engine fault codes) really fast.
Check your Live data I/M Readiness
Automatic VIN acquisition and decoding makes it easy to read manufacturer specific codes and enhanced mode data
Fast read and clear vehicle error codes for 1996 US-Based, 2001 EU-Based and Asian cars, and newer OBD II/Eobd & CAN domestic or import vehicles.Besides,it also shows live vehicle sensors data in text and graph format and allows you to focus on any suspicious or symptom-specific data parameters.

69.99 $

Check Price At Amazon



With this tool you can read your trouble code memory at home and then use Google or Bing to find information about the code or check out one of our other articles for a more detailed guide:

How to troubleshoot your car in 5 steps

Generic DTC code list

But I still recommend you to go to a workshop with better diagnostic tools to make a correct troubleshooting.

When you have detected the fault and fixed it you have to go out and try your car under the same conditions as before. Try to remember at which speed, gear and load it happened. Try to induce the faults again to be 100% sure that the problem is fixed.


You can check this video if you want to get more information about how to find and research about trouble codes:


  • Don’t panic when the limp mode occurs. It’s designed to make your engine survive to make sure that you can drive to the workshop to repair the problem.
  • Limp mode is often caused by an electrical problem with the engine or transmission
  • Limp mode is a security state
  • Make sure that you go to a workshop or try to fix it yourself as soon as possible. It’s not good to drive around with.


If you have any questions that still is unclear you can either Comment below or ask a question at our site and I will help you out.
You can also give us feedback if you want us to change anything in this article.





What is Limp Mode And How To Fix It?
Article Name
What is Limp Mode And How To Fix It?
Limp mode is a security function for the engine. The engine is set into limp mode when the car has detected a fault with the engine or transmission. In this article, I will talk about what limp mode is and how you can fix it yourself.
Publisher Name
Ask A Master Mechanic
Publisher Logo

About Ask A Mechanic AdminDiagnostic Technician

Hello. I live in sweden and work as an Automotive Diagnostic Technician. Worked with the most brands in the most advanced fault diagnostics. Im here to answer all your automotive questions. If you have any private questions you could send me a PM and I'll answer them as soon as possible!

Follow Me

Leave a reply

Car Fault Questions | Ask A Mechanic is Stephen Fry proof thanks to caching by WP Super Cache