What is limp mode on a car? Symptoms and causes

Stuck crawling home with warning lights flashing? Limp mode is your car’s way of protecting itself. Here’s everything you need to know, plus firsthand experience from the Carwow team.

If you experience a loss of power and see warning lights on your dashboard, your car may have entered limp mode. It’s called “limp mode” because the car limits its power to protect itself from potential damage, while still allowing you to drive – albeit slowly – to your garage or destination.

There are several reasons a car can enter limp mode. In this guide, we’ll cover the common symptoms, causes, and potential remedies. We’ll also explain how to bypass limp mode, and whether doing so is ever a good idea.

Remember, you can buy a brand new or used car right here on Carwow. We’re here to help you through every step of your car-changing journey.

What is limp mode on a car?

Think of limp mode as your car’s way of protecting itself. If a fault develops – typically in the engine or transmission – the car may restrict revs and power. The idea is that the car remains driveable, but only slowly, to prevent the fault from causing serious damage.

Aside from the sudden loss of power and dashboard warning lights, your car may show a few other symptoms when in limp mode:

• Auxiliary functions, such as heating and air conditioning, may stop working.
• Maximum revs may be limited to as low as 2,000-3,000rpm.
• In an automatic, you may be locked into a low gear.
• Maximum speed may be restricted to 30-50 mph.

Common causes of limp mode

Limp mode is activated when the Electronic Control Unit (ECU) detects that something is operating outside predefined parameters. This can be caused by a variety of factors, such as:

• Extremely low levels of oil or coolant.
• Transmission errors, such as when the gearbox can’t change gears properly.
• Brake malfunctions, including seized brakes or a hydraulic leak in the system.
• Wiring issues, where a problem with the wiring loom may cause erratic behaviour.
• Engine issues, such as misfiring or turbo problems.

What sensors can cause limp mode?

Limp mode is triggered when the ECU detects abnormal readings from key sensors, limiting power to protect the engine or transmission.

Common sensors that can cause limp mode include:

• Mass Air Flow (MAF) sensor – checks how much air is going into the engine.
• Throttle Position Sensor (TPS) – monitors how far you press the accelerator.
• Manifold Absolute Pressure (MAP) sensor – measures engine load and air pressure.
• Oxygen (O2) sensors – check exhaust gases to make sure the fuel mix is right.
• Coolant Temperature Sensor (CTS) – keeps track of engine temperature.
• Transmission Speed Sensors – measure the speed of your gears.
• Brake sensors – monitor ABS and brake system issues.
• Turbo boost sensors – track turbocharger pressure.
• Knock sensor – detects engine knocking or pinging.

How to get your car out of limp mode

The reasons a car enters limp mode can vary, and some can be serious, so it’s best to have it checked by a mechanic as soon as possible. They can take the car out of limp mode once the fault is fixed.

Never ignore the warning signs. How urgently you need to attend to the issue depends on how far you are from a safe stopping point and how the car is driving.

If possible, check the oil and coolant levels, as well as any obvious signs of wiring damage or fluid leaks under the car.

Sometimes you may be able to reset limp mode by turning the car off and on again after about 30 seconds. If the warning lights disappear and the car behaves normally, it may have been a temporary glitch. However, limp mode can return immediately during system checks or after some driving.

If the car goes back into limp mode, have it thoroughly checked by a professional. You can either drive it to your garage if the issue is minor, or have it towed. Repair costs can vary widely: from a simple

ECU reset costing a small labour charge, to thousands of pounds if the problem involves the engine or gearbox.

How to bypass limp mode

Sometimes, limp mode can be temporarily cleared by restarting the vehicle after a short wait. In some cases, a mechanic or technician can reset the electronic systems electronically.

It’s also worth checking basic things such as oil and coolant levels, in case low fluids triggered the mode.

However, it’s important to remember that bypassing limp mode does not fix the underlying problem. If restarting the car or topping up fluids doesn’t solve the issue, the car should be inspected by a qualified mechanic to prevent potential damage.

Can I drive my car in limp mode?

The whole point of limp mode is that the car is still driveable, but with reduced performance. If the car feels seriously wrong or unsafe, it’s best to have it recovered by a mechanic.

Driving in limp mode for an extended period can make the underlying problem worse. If your destination is far away or involves fast roads, where reduced performance could be dangerous, it’s safer to have the car rescued.

My car went into limp mode – here’s what happened

News editor Jamie Edkins has experienced limp mode in the past, here’s what happened and how he dealt with it.

Before my days as a motoring journalist, I was a delivery driver. Our fleet of vans wasn’t maintained all that well, so I wasn’t shocked to experience mechanical issues on one of my runs.

I was driving down a major A-road when the engine light started flashing, along with an error message for the emissions system. I felt most of the engine’s power disappear, and before I knew it I was reduced to a 15-30mph crawl.

The important thing to remember in this situation is not to panic. It can be nerve-wracking to suddenly lose power on a fast moving road, but I switched on my hazard lights and moved as far left as I could to show people behind me that I was experiencing mechanical issues.

I found a safe place to pull over, switched the van off and called the breakdown company. It turns out the issue was with the AdBlue injectors, which pump a special fluid into the exhaust to clean up the tailpipe emissions. Faults with emissions systems are a common reason your car or van might go into limp mode, but it can be caused by a whole host of engine issues.

Limp mode FAQs

How fast can I drive in limp mode?

The speed you can drive in limp mode depends on the limits set by the manufacturer. In most cases, you will be restricted to around 30-50mph, with the engine revs limited to about 3,000rpm. If your car has an automatic transmission, you may also be locked into a lower gear.

How can I disable limp mode permanently?

Even if you could find a way to permanently disable limp mode, it’s not recommended. Limp mode is designed to prevent a fault from causing serious damage, potentially saving you thousands of pounds in repairs. In some cases, it can even help prevent accidents by reducing the risk of catastrophic failure while driving.

The safest and most effective way to get your car out of limp mode is to have the underlying fault diagnosed and repaired by a qualified mechanic.

Is limp mode expensive to fix?

It depends on the issue. Limp mode repair costs range from under £100 for simple sensor fixes to over £2,000 for major engine or transmission failures.

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Looking for a new set of wheels? With Carwow you can sell your car quickly and for a fair price – as well as find great offers on your next one. Whether you’re looking to buy a car brand new, are after something used or you want to explore car leasing options, Carwow is your one stop shop for new car deals.

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