Have you ever driven your car and then suddenly you’re not getting any power? And then your check engine light suddenly turns on? That means your car is in limp mode. A check engine light denotes that there’s something wrong with your car’s powertrain.
It could be the engine, the gearbox, or the exhaust system. If this happened to you recently, don’t worry. We’ll discuss the limp mode in this post, from what it is, why it happens, and how to fix your car.
- What Is Limp Mode?
- Common Causes For Limp Mode
- Signs That Limp Mode Is On
- Fixes & How To Reset It
- Final Conclusion
- Frequently Asked Questions (FAQs)
Limp Mode Car
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Limp mode (sometimes called limp home mode) and fail-safe mode is basically the self-preservation modes your car has. This means your car has a serious issue and continuing to drive it can cause severe damage. The issue most commonly stems from its transmission.
It engages limp mode to limit the engine power output and transmission to prevent such damage. You will notice that your car can only engage one gear, maybe two in some cars. And it will limit the speed to just around 30 – 45mph.
The purpose of limp mode is so that you can continue driving to get home or your destination while preventing any further damage while doing so. In most cases, your car will also turn off accessories like the air-conditioning and radio to preserve energy to run the car. But what exactly causes limp mode?
Limp Mode Causes
As mentioned, the issue most likely stems from your transmission unit. But other things may also cause your car to engage limp mode, here are the possible causes:
1. Low Transmission Fluid
The transmission is a collection of gears that transmits power from the engine to the wheels more efficiently. Since the gears inside experience a lot of friction, they need a lubricant to reduce friction and heat. This keeps your transmission running smoothly and prolongs its lifespan.
The transmission fluid typically needs to be replaced every 30,000 to 50,000 miles. If the fluid is old, it won’t be as effective in lubricating the transmission. Additionally, transmission fluid can leak if the gasket or pan is worn out or damaged.
If the transmission doesn’t have enough fluid (or, if you notice the sign of low transmission fluid), it can lose pressure which prevents it from working properly. Also, not enough fluid means the transmission won’t be lubricated properly. This will increase friction and heat, leading to an overheating transmission.
When the transmission overheats, it can lead to severe damage. This is why it would engage limp mode so that the transmission’s performance would be limited and prevent damage.
2. Failed Clutch, Linkages, Or Solenoid
If the clutch or linkages within the transmission have failed or been misaligned, your car may also engage limp mode. This is to prevent any more stress or damage to the transmission, saving you from an expensive transmission rebuild.
The linkage is responsible for shifting your gears, if it fails then the transmission will have trouble changing gears. This is why it engages limp mode as your car will only use one gear in limp mode.
If you have an automatic transmission, you may have a faulty solenoid. A solenoid is an electro-hydraulic valve that controls the flow of transmission fluid and it is what allows the automatic transmission to change gears.
A bad solenoid will be unable to perform its job, disrupting the operation of the transmission. You will notice your transmission is slow to respond or even refuses to change gears. When the problem is bad enough, the car will turn on limp mode to preserve the transmission.
3. Sensor Malfunction
The car is a very complex piece of machinery and it needs a lot of sensors to make sure everything works together perfectly. Most modern cars will use a speed sensor (you can learn more in our guide on the transmission speed sensor location), a Manifold Absolute Pressure (MAP), and a Throttle Position Sensor (TPS) to feed the car’s computer with various information about the car’s condition.
It then uses this information to tell the transmission when to upshift or downshift. For example, if the car detects you’re putting your foot down, it will automatically shift gears down because it’s assuming you want more power and you want to go fast.
How does this cause the car to go into limp mode? Well, your car’s computer is designed to receive information in a pre-programmed range specified by the manufacturer. If it receives information outside of this range, it will engage a “secondary” programming or in other words, limp mode.
For example, let’s say the TPS is supposed to send information between the value of “1-10”. If your car’s computer suddenly receives a value of “12”, it will assume that there’s an error with the TPS sensor.
It then engages limp mode to prevent any damage from happening. This of course is an oversimplification, but that’s generally how it works. If the sensor malfunctions, it may send incorrect information which puts the car in its fail-safe mode.
4. Damaged Wires
Since there are a lot of sensors and electrical components, there are also a lot of wires in your car. Dirt, road debris, or even rodents finding their way into your car can damage your car’s wiring.
If there’s damage to the wires, the sensor and other electrical components won’t be able to send the correct signals and information to your car’s computer. This leads the computer to think that there’s a malfunction with a certain component.
This is basically the same as the sensor malfunction. But rather than because of a faulty sensor, the problem stems from wiring damage.
5. Engine Misfires
Engine misfires can cause severe performance issues, and if they occur consistently, they can damage the engine. A misfire happens when one or more of the engine’s cylinders don’t fire properly. This can be due to faulty spark plugs, clogged fuel injectors, or even timing chain issues. If the vehicle’s computer detects repeated misfires, it may trigger limp mode to protect the engine from further damage.
6. Exhaust System Blockage
Cars are designed with an exhaust system that expels burnt gases from the engine. If there’s a blockage in the system, especially in the catalytic converter, the engine might not expel these gases efficiently. Such a blockage can cause the engine to run at higher temperatures and may lead to reduced performance. To prevent potential damage, the vehicle might enter limp mode.
7. Overheating Engine
Cooling systems in cars are vital for maintaining the engine’s temperature. Factors like a faulty water pump, damaged hoses, or a compromised radiator can cause the engine to overheat. When the temperature reaches a critical level, the car’s computer will activate limp mode to reduce power and mitigate the risk of engine damage.
8. Electronic Throttle Control Issues
Modern vehicles often use electronic throttle controls, replacing the traditional throttle cable. This system communicates electronically with the vehicle’s computer, adjusting the throttle based on the driver’s input. If this system malfunctions, it might send inaccurate signals. Consequently, the computer may enable limp mode, limiting the car’s acceleration and speed.
9. Turbocharger Problems
For vehicles equipped with turbochargers, any malfunction in the turbo system can have a significant impact on performance. Whether it’s a leak in the system or a failing turbo, any issue might cause the car to lose power. To protect the engine and the turbo unit from damage due to overpressure or overheating, the vehicle may resort to limp mode.
10. Failing Battery or Alternator
The battery provides the initial power to start the engine, while the alternator continuously recharges it during operation. If either of these components fails, it can lead to insufficient power supply to the car’s electrical systems, including the computer. When the computer doesn’t receive adequate power, it might not function correctly, possibly triggering limp mode to ensure safety.
11. Faulty Fuel Delivery System
A car’s performance is closely tied to its fuel delivery system, which includes the fuel pump, injectors, and filters. If there’s an issue anywhere in this system – be it clogged filters, failing pumps, or malfunctioning injectors – the engine might not receive the right amount of fuel. As a result, it can lead to rough idling, stalling, or reduced power. To protect the engine, the car might enter limp mode until the issue is resolved.
Limp mode is a critical feature in modern cars, designed to protect the vehicle and its occupants. If your car ever enters limp mode, it’s essential to diagnose and address the root cause promptly. Regular maintenance and understanding potential causes can help you prevent scenarios leading to limp mode. Always consult with a professional mechanic when dealing with these issues to ensure your vehicle remains in optimal condition.
Limp Mode Symptoms
Not sure if your car is in limp mode? These are the signs that your car is in limp mode:
1. Limited Speed, RPM, And Gear Changes
The first sign you will see is a limit to your car’s performance. The computer will limit your car to about 30 – 45 mph, and your engine usually won’t be able to rev over 3,000rpm or so. If you have an automatic, your car will also limit the transmission. Usually, it won’t be able to go over third gear, or sometimes limiting it to just one gear altogether.
2. Slow Acceleration
Not only speed is limited, but the engine power output will also be very limited. This means your car won’t have as much power as usual, and acceleration will be very slow. Remember, the purpose of limp mode is to prevent damage by preventing your car’s components from working as hard as usual.
3. Check Engine Light
The check engine light will usually accompany limp mode. If you see the symptoms above and the check engine light is on, then your car is in limp mode. A check engine light is there to warn the driver that there’s an issue with the car’s powertrain.
Your car may illuminate the check engine light before engaging in limp mode. This usually happens when the issue isn’t serious enough, so it will still allow you to drive as normal.
This is why you shouldn’t ignore a check engine light. It indicates an issue with either the engine, the transmission, or the exhaust system and you should address it before it gets severe. Ignore it long enough and the car will engage the fail-safe settings.
How To Get Car Out Of Limp Mode
It can be quite startling when you’re driving normally and then suddenly your car just isn’t performing as it normally would. But don’t panic! As mentioned, the limp mode is your car’s self-preservation mode, meaning it’s doing everything it can to prevent severe damage to the powertrain. Here are our tips on what to do if your car is in limp mode:
- Stop your car on the hard shoulder or an uncrowded part of the road so that you’re out of the way of other motorists.
- Put the transmission in P or Park.
- Turn off the engine and the ignition switch, then wait for about 60 seconds.
- Turn the engine back on and try driving away again. If the car is out of limp mode, then continue driving as you normally would. It might just be an error that caused the limp mode. But we recommend not pushing the car too hard and taking your car to a repair shop later on for a diagnosis.
- If the car is still in limp mode, drive back home or to a repair shop carefully. Go to whichever is the closest, the sooner you stop driving, the better. Stay in the right lane since you won’t be able to go very fast.
However, there are some scenarios where you shouldn’t continue driving in limp mode:
- You shouldn’t continue driving if the engine is overheating, pay attention to the temperature gauge.
- The oil warning light is on.
- If the check engine light is flashing, stop driving immediately. Under no circumstance, you should be driving with the check engine light flashing as it indicates a serious issue and can damage the car. You need to tow the car.
- If weird noises are coming from the engine or the transmission, stop the car. Any noise in the engine bay can be a bad sign.
How To Reset Limp Mode
So, how do you get your car out of limp mode? As mentioned, the main cause is usually a transmission issue. When the transmission doesn’t have enough fluid and overheats, the car will limit performance to help prevent damage. So, naturally, you should check the transmission. But here’s what you can do first:
1. Turn The Car Off And Let It Cool Down
It’s also possible that the transmission is overheating because of external factors such as the weather. If you live in a hot climate or are driving during a heatwave, while unlikely, it’s possible that the transmission is overheating because of external temperature.
Turn off your car until it cools down and then turn it back on and see if the car is still in limp mode. If it’s not, you can continue driving until you reach home. However, we recommend checking your transmission fluid level. That’s because a low transmission fluid level (which can be noted if you’re seeing low transmission fluid on dipstick) is the most likely culprit for your car going into limp mode, here’s how you can check it:
2. Check The Transmission Fluid Level
Here’s how to check your car’s transmission fluid level:
- Most cars have a transmission fluid dipstick. This is usually located at the back of the engine and is marked with a red handle that sometimes says “Transmission”.
- You should check the dipstick when the car is still warm. Some cars may even require the engine to be running to get an accurate reading. Check with your owner’s manual on whether or not the engine should be running.
- Make sure you’re on a surface level, then pull out the dipstick.
- Wipe the stick with a rag, and then reinsert the dipstick. Ideally, you should wipe it with a white rag or tissue. This way, you can see the color of the fluid. If it’s red, then it’s good. If it’s dark red or even black, it’s a good idea to replace the transmission fluid.
- Pull it out again and see where the fluid level is. The dipstick will have Maximum and Minimum markers on it. If it’s below the minimum level, you’re going to have to refill that. Possibly change it entirely with new fluids.
3. Add Transmission Fluid And Check For Leaks
If you need to add transmission fluid, the first thing you need to do is check what type of fluid you should use. You should be able to find this in your owner’s manual. Once you have the correct transmission fluid for your car, use a plastic funnel to insert the fluid through the dipstick tube. Since you’re only topping up, use about one quart. Afterward, check if your car has enough fluid. If it’s still low, add a quart at a time until it reaches the appropriate level.
Once you sort that out, you should check for leaks. Transmission fluid rarely needs topping up, so if your transmission fluid is low, you may have a leak. Check underneath your car if any red fluids are dripping off from the front middle to the middle of the car. If there’s a red or dark red fluid dripping off, you have a transmission leak and you will need to fix that.
The cost to repair a transmission fluid leak will depend on where the leak is coming from. If the cooling lines, rear gasket or seals, or the pan bolts are the source of the leak, it should cost you no more than about $200 – $250 to repair. However, this gets expensive if the leak is coming from the front seals or gaskets of the transmission.
This is because replacing those seals or gaskets will require your mechanic to remove the transmission from the car, and that will take some time and add labor costs. The average cost is somewhere around $400 – $600 but can easily get to as high as $1,000 for certain cars.
We wrote a comprehensive guide on transmission leak repairs and you should read it if you need to fix a transmission leak.
Can Low Transmission Fluid Cause Limp Mode
If the transmission fluid is at the appropriate level, your next step should be scanning the On-Board Diagnostic (OBD) system with an OBD scanner. As mentioned, the limp mode is usually accompanied by a check engine light. The check engine light is your car’s way of telling you that there’s something wrong with the powertrain.
The system works by using several different sensors that feed information to the Engine Control Unit or Powertrain Control Module. When it detects an irregularity, it will try to fix that on its own. If it can’t get rid of the problem, it will register an error code which will then trigger the check engine light.
You can scan and find out the error code by scanning the OBD port with an OBD scanner. These error codes can’t tell you exactly what’s causing the problem, but they will help you identify where the problem is and narrow down the possible causes. This makes the diagnosis process much quicker.
To scan the OBD, you will need an OBD scanner or reader. If your car was made in 1996 or after, then you need an OBD-2 scanner. They’re usually around $30, or you can buy a good one for around $100. No need to spend thousands of dollars on professional ones as those are intended for mechanics. And don’t worry, OBD-2 is universal and will work with any car.
1. How To Use An OBD-2 Scanner
Once you get a hold of the OBD-2 scanner, here’s how to use it:
- Plug the reader into the car’s OBD port. This port is often located underneath the dashboard area, either above your pedals or knee. Keep in mind that some cars might have their port hidden out of sight. Check your owner’s manual or online to see where it’s located in your car.
- Once plugged in, turn on the OBD scanner. It should immediately scan the car. However, some scanners might require you to input additional information such as make, model, model year, VIN, etc.
- It will then display the error codes it has found. A more complicated scanner might also display a description of what’s wrong with the car, but if you have a simpler scanner then you should take note of the error codes on display.
- Afterward, check what the error codes indicate. This will help you diagnose the car and narrow down the possible causes.
Here are some error codes you might see and what they mean:
2. Possible Error Codes
- P0218: Transmission Over Temperature. This error code means that your transmission is overheating. If the fluid is at the correct level, then check its condition if it needs replacing. It’s also possible you have a faulty solenoid that’s disrupting the flow of fluid into the transmission which causes it to overheat. A transmission fluid change costs (for more insight, check out our guide on should I change transmission fluid after 100k miles and how often should you change transmission fluid, in addition to should you change transmission fluid on high mileage cars) somewhere between $100 – $400. Meanwhile, a pack of new solenoids will set you back anywhere between $250 – $600 including labor.
- P0300 – P030x: Ignition System Misfire. These error codes mean there’s a misfire inside the engine. P0300 means there are multiple misfires, while a number at the end of the code specifies which cylinder is misfiring. For example, P0301 means that cylinder one has a misfire. A misfire is usually caused by bad spark plugs, and this can cause the car to go into limp mode if the problem is bad enough. Spark plugs are no more than $50 a set to replace, but if your problem stems from ignition coils, then they can be as high as $270 to replace.
- P0101: Mass Air Flow (MAF) Malfunction. The MAF is a sensor that measures the amount of air the engine is taking to help control the fuel-air mixture. If the MAF detects an irregularity, it will send an error code. The P0101 code can mean a number of things, including dirty or faulty MAF, damaged or disconnected air intake boot, a vacuum leak, a clogged air filter, or a bad catalytic converter (it helps to understand the catalytic converter life expectancy and how to diagnose a code P0420, as well as the P0101 code Nissan). Since the MAF plays a major role in your engine’s operation, a malfunction may trigger the limp mode. A MAF replacement cost is usually around $240 – $330.
3. If You See Other Error Codes
There are tons of other possible error codes that you might see, and there’s no way we can list them all down here. These are just some of the common ones you might see if you experience limp mode.
If you see other error codes, you should be able to find what they mean in your owner’s manual. There is also tons of information online on what these error codes mean. Once you find what they mean, then you can find out what might be causing them and find a fix.
After you fix your car, the check engine light may stay on and needs to be reset. You can clear the light by clearing the error codes using the OBD scanner after you fix the problem. Do not clear the error codes before you fix the problem and do not ignore the check engine light.
Limp Mode: In Conclusion…
Limp mode is your car’s way to prevent severe damage to the powertrain unit by limiting performance. This prevents the powertrain from working too hard and avoiding severe and expensive damage.
If your car is in limp mode, you can continue driving as long as there are no weird noises, no flashing check engine light (such as the flashing check engine light in a Ford), and the engine isn’t overheating. But the sooner you stop driving, the better.
If the limp mode goes away on its own, you should still check your car and see if it has any problems. It’s possible that hot weather was overheating your car’s transmission which caused the car to go into limp mode.
But it’s more likely that you have an underlying problem with the powertrain unit. Check and fix the problem if there are any to avoid expensive repairs in the future.
Limp Mode: Frequently Asked Questions (FAQs)
If you’re still curious to learn more about a car’s limp mode, our FAQs here might help…
How To Bypass Limp Mode
There are several ways to bypass limp mode and get your car running properly again. First off, you could try stopping and turning off the engine for 5 minutes to let your car rest. This might give the computers time to recalibrate, and once that’s done, try powering your car on again. Continue driving while gradually shifting into the highest gear while ensuring that it’s fully turned off. Otherwise, there are other ways of bypassing the limp mode. For example, you can use an OBDII diagnostics tool to reset error codes and turn off the limp mode. Or, you could also disconnect the battery and drain the ECU entirely to try and hard reset it.
Can Low Oil Cause Limp Mode
Among the many issues that’ll prompt limp mode to turn on is a low level of critical fluids in your car. As such, if your car doesn’t have enough oil or transmission fluid, it would cause the limp-home failsafe mode to turn on. This is more so for transmission fluid than motor oil, though. Usually, low transmission fluid (especially if your car has automatic transmissions) would entail a reduction in hydraulic pressure. Without that pressure, your (automatic) transmission won’t be able to effectively change gears due to the low transmission fluid. Thus, prompting limp mode to turn on and restrict power to the transmission to prevent further damage.
How Much Does A Car Diagnosis Cost
If your car’s limp-home failsafe mode is turned on and you can’t figure out what’s wrong, it’s worth sending it over to a mechanic for a quick check-up and diagnosis. In doing so, they’re able to more effectively inspect each part of a car and let you know precisely what’s caused it to appear, in the first place. However, do know that even a quick diagnosis may cost you. On average, a diagnostics check-up would cost you between $60 to $100, on average. Some mechanics may even charge upwards of $400, but only if they need to conduct a very thorough diagnosis. The roughly $100 mark is more realistic, albeit some mechanics are kind enough to not charge anything for merely a simple diagnosis.
Can A Car Throw Codes Without Check Engine Light
Most often, the check engine light on your dash is interlinked with diagnostics error codes. Simply put, if the ECU has determined that something’s off with your car, it would store error codes that you can use for diagnosis later on. But, in so doing, the ECU typically lights up the check engine light as an alert that there are some codes that you might want to check out. Granted, there are also certain situations where error codes can be stored, but without the check engine light appearing. Sometimes, this is because a previous repair job hadn’t properly cleared out the existing error codes, causing it to appear once again if you plug an OBDII scanner in.
Is It Safe To Drive With Reduced Engine Power
If and when the Reduced Engine Power failsafe mode comes on, the first thing that you should do is drive your vehicle to a safe location. Or, stop it by the side of the road, if it’s feasible, and turn on your hazards to warn other motorists. If there’s a garage nearby or if your home is just around the corner, then it’s safe to drive with the Reduced Engine Power message lit up. However, it’s a bad idea to drive for extended periods of time while it’s turned on. Mainly, because your car’s speed and driveability are severely reduced. Furthermore, the issue that’s caused this message to pop up in the first place may worsen over time.