If you’ve noticed that your car won’t go over 30 mph, you’re probably wondering what the cause could be. It could be anything from a simple fix to a more serious repair, but either way, it’s important to diagnose the cause immediately.

The most common cause of a car not going past 30 mph is that it has gone into limp mode. This safety feature built into modern cars will limit the engine speed when something goes wrong. The most likely cause of this is an issue with the car’s sensors, such as the mass airflow or throttle position sensor. If this is the case, it can usually be fixed with a simple reset.

In this blog post, we’ll discuss some possible causes why your car won’t go over 30mph and the steps you need to take to diagnose and fix the problem.

Car Won’t Go Over 30MPH And Check Engine Light Is On

If your car won’t go over 30mph and the check engine light is on, the car has entered limp mode. Modern cars have a safety feature called limp mode which limits the engine speed to prevent damage. This could be caused by a number of issues, some of which we will discuss.

Low Fluid Levels

One of the most common causes of this issue is low fluid levels. The most common fluid to check would be the oil. A low oil level can cause serious damage to your engine. Ensure all other fluids, such as coolant and brake fluid, are at the correct level.

Blocked Fuel Filter

If your fuel filter is blocked, it can cause the engine to lose power and not allow your car to accelerate beyond 30mph. You should replace the fuel filter every couple of years to maintain peak performance for your vehicle, so make sure you replace it regularly as part of regular maintenance. 

Clogged Catalytic Converter

The catalytic converter helps reduce harmful emissions from your vehicle by converting them into harmless ones. Clogging can restrict airflow and lead to a loss of power. This could explain why your car won’t go over 30mph with the check engine light on. If this is the case, you’ll need to replace the catalytic converter to restore full performance.  

Bad Mass Air Flow Sensor (MAF)

The mass air flow sensor measures how much air enters the engine so that more fuel can be added for optimal performance. If this sensor goes bad, it will cause a drop in power. This could explain why your car won’t go over 30mph with the check engine light on. You’ll need to replace the MAF sensor to get the engine back to full performance. 

Faulty Throttle Position Sensor (TPS)

The throttle position sensor tells the computer how far open or closed the throttle plate is, affecting how much fuel gets injected into the cylinder during combustion. If this sensor fails, it could limit how much power is available, causing your car to not go over 30mph with a check engine light on. You’ll need to replace this to get your car running properly again.

Transmission Issues

A transmission issue can cause loss of power which could explain why your car won’t go over 30mph. A worn clutch, low fluid levels, or a faulty sensor are common transmission issues. You can check your car’s dipstick for the correct fluid levels and ensure the clutch is firmly in place. It’s also possible that your car’s transmission control module is malfunctioning. It’s worth checking the sensors to make sure they’re functioning properly.

Car Won’t Go Over 30MPH With No Check Engine Light

If your car won’t go over 30mph and there is no check engine light on, it could be caused by several things.

Bad Spark Plugs

One of the most common causes of a car not going over 30mph is bad spark plugs. If your spark plugs are worn out or faulty, they won’t be able to create the spark necessary for combustion, leading to an underpowered engine.

To check if this is the issue with your car, remove each spark plug and inspect it for signs of damage. If you find that one or more of them needs to be replaced, make sure to replace them all at once. 

Failing Clutch

Another potential cause of your car not going over 30mph is a failing clutch. The clutch transfers power from the engine to the transmission, allowing the wheels to turn and propel the vehicle forward.

If your clutch has an issue, it can prevent power from being transferred properly and cause your car to lose speed. To diagnose this issue, take your car in for an inspection and have a professional check out the condition of your clutch system. 

Blocked Air Filter

A blocked air filter can also lead to issues with speed and acceleration in cars. The air filter’s job is to remove dust, dirt, and other contaminants from incoming air before it enters the engine. If it becomes clogged, it can restrict airflow into the engine causing poor performance at higher speeds.

To fix this issue, open up the hood and inspect (or replace) the air filter yourself. You can also take it to a mechanic who can do it for you quickly and easily.  

Dirty Fuel Injectors

Finally, dirty fuel injectors are another common culprit behind cars not going over 30mph without any warning lights coming on. Fuel injectors spray fuel directly into an engine’s combustion chamber where it mixes with oxygen before it is ignited by spark plugs.

If these injectors become clogged or suffer from corrosion, they won’t be able to deliver enough fuel into an engine. This causes decreased performance when trying to accelerate past 30mph.

FAQ

Can I Drive A Car In Limp Mode?

Driving a car in limp mode is still possible, but not recommended. Limp mode restricts the engine from going over a certain speed, usually around 30mph. So you may be able to get where you need to go, but it won’t provide the full performance your car normally has.

How Do I Get My Car Out Of Limp Mode?

The best way to get your car out of limp mode is to diagnose and repair the issue that caused it in the first place. This could be a transmission issue, bad spark plugs, a failing clutch, a blocked air filter, or dirty fuel injectors. It’s important to identify the root cause of the issue before attempting to repair it. After repairing it, you can reset the ECU to get your car back to normal.