Reduced engine power warning (what is the cause?)
When your vehicle is working as it should, every day is sunny and bright. However, as soon as something goes wrong, the world feels like it could fall apart. There’s nothing more discouraging than seeing the reduced engine power warning alert on your dashboard or feeling your car’s performance decline.
To help you deal with this confusing situation, we discuss the meaning of the reduced engine power warning. We also look at the causes of this engine alert and show you how much it can cost to repair it.
The meaning of the reduced engine power warning
When the Reduced Engine Power warning appears, it means your vehicle’s performance is limited. The PCM detects a system failure and alerts the message to illuminate. Along with the warning message, the engine may not operate normally.
Reduced power may prevent the vehicle from moving and may prevent you from accelerating. In extreme cases, the PCM will restrict fuel supply to the engine, leaving you with a car that won’t run.
Some people call this system a fail-safe mode. However, it is also known as limp mode because the warning gives you time to get home without further damage to the engine or transmission.
Causes of the reduced engine power warning
The reduced engine power warning is often caused by faulty engine sensors, such as a faulty oxygen sensor, MAF sensor, or throttle body. It can also be caused by a loose connection to one of these sensors. A clogged catalytic converter is also usually the culprit.
However, the reduced engine power warning can be caused by many different reasons and therefore you should never simply replace parts that you think are faulty.
The easiest and safest way to determine the cause of the reduced engine power warning message is to check the fault codes with an OBD2 scanner. When the message appears, there is almost always a trouble code stored in the system. It can save you a lot of money by not replacing the wrong parts.
Here are some other ideas about what may cause the reduced engine power warning to activate:
1. Loose connection
All major components of your vehicle are connected with cables. If there is a short circuit in the electrical system or one of the wires is damaged, the engine may go into safety mode. This problem can also exist if you have a loose clamp or a ground wire that is not connected properly.
Although a loose connection is easy to repair in most cases, it is not always easy to find. You will need to perform a full systems inspection to find the fault.
2. Defective oxygen sensor
Oxygen sensors are needed to measure the amount of O2 leaving the system through the exhaust. If too much or too little oxygen is coming out, the ECU will adjust the air-fuel ratio to balance performance.
However, a faulty sensor can send erroneous information to the computer, causing adjustments that should not be made. This creates an imbalance in the air and fuel mixture, which not only causes poor performance and engine problems but can also trigger the reduced engine power warning.
RELATED: 5 Symptoms of a Bad Oxygen (O2) Sensor
3. Throttle body problems
The throttle body contains several parts that could deteriorate and cause these warnings. First of all, the throttle valve is responsible for letting air into the engine. When this valve breaks, the proper amount of air cannot be achieved.
Carbon can also build up around this valve, causing operational problems. When the engine cannot get enough air, it will misfire and sputter while generating warnings on the dashboard.
Not far from the throttle valve is the throttle position sensor, which must also function properly to allow the free flow of air. This sensor reads the position of the accelerator pedal and tells the computer to open the throttle valve. However, if the sensor is faulty, the valve cannot get the correct data, and air will be squeezed.
RELATED: 8 Symptoms of a Bad Throttle Body (and Replacement Cost)
4. Defective ECU
The engine control unit is the brain of the entire operation. All sensors communicate what is happening to the ECU so that appropriate adjustments can be made. If the air-fuel mixture is not good, it is the ECU that modifies what is happening for better performance.
However, when the ECU starts to fail, several problems can arise. You may begin to notice sluggish performance as the engine compensates for problems that may not even be occurring.
RELATED: 5 Symptoms of a Bad Engine Control Module (ECM)
5. Defective mass air flow sensor
You will find the mass air flow sensor between the intake manifold and the engine air filter. Its job is to measure the pressure and density of the air entering the engine.
Once these measurements are made, the information is sent to the ECU so that the correct fuel ratio can be applied. When the MAF sensor fails, incorrect data is sent, which creates problems with reporting and causes the warning lights to come on.
RELATED: 8 Symptoms of a Bad MAF Sensor
6. Clogged catalytic converter
After the exhaust manifold, you will find the catalytic converter. The main purpose of this vital component is to convert dangerous exhaust gases into less harmful pollutants. If the engine has not been running properly or the vehicle is aging, the catalytic converter can become clogged.
Once this happens, not only will the vehicle fail the emissions test, but you will experience engine performance issues. It won’t always trigger the reduced engine power warning, but you can expect the Check Engine Light to come on at a minimum.
RELATED: How to Clean a Catalytic Converter (Without Removing It)
7. Transmission failure
Transmission problems are never fun to deal with and can cause a lot of headaches. If the transmission slips or the fluid has reduced, you can expect to see error codes.
Although people don’t think that a reduction in engine power is related to transmissions, these two systems are related. If none of the other culprits are to blame, it’s time to take a look at the transmission.
Reduced Engine Power Warning Repair Costs
The cost to repair a reduced engine power warning ranges widely from $0 to $2,500. The only way to know the exact cost would be to determine what is causing it.
Using an engine code scanner should help you determine where the fault is. The OBDII scanner will read all error codes and show you which systems may be to blame.
Ideally, you’ll notice a loose connection, which won’t cost you anything to fix if you can reestablish the link. However, replacing the catalytic converter or changing the ECU could be an expensive solution that could lead to scrapping your vehicle.
You should never drive with the reduced engine power warning light on. If emergency mode has been activated, you must immediately drive the vehicle to a safe location and turn it off. Turn on your hazard lights to let other drivers know you are in trouble.
If you have more than a few miles to go, it is recommended that you have the vehicle towed. You don’t want to be stranded on the side of the road or cause an accident due to lack of power.
