Post Written By AutoPadre
The reduced engine power warning light indicates that the vehicle's computer system has intentionally reduced your vehicle's engine performance.
Reduced engine power occurs when the vehicle's computer receives a signal indicating a problem from one of its sensors.
It lets you safely get to a professional mechanic while hopefully minimizing further damage.
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The Reduced Engine Power warning light is activated by your vehicle's computer system when it detects a failure in one of the vehicle's components.
The reduced engine power mode is often called "limp mode."
When your vehicle enters reduced engine power mode, the engine's performance is inhibited. As a result, it can cause your car to suddenly lose power.
It is built into your vehicle to prevent severe damage to your vehicle's components by allowing you to get your car to a mechanic to get it checked out.
Occasionally, the fuel system may be disabled, requiring a tow, so it's important to troubleshoot the problem and get it fixed as soon as possible.
You can drive with the engine power reduced mode, but it is not ideal and should be kept to a minimum for several reasons.
First, you could be causing damage, leading to an even more expensive fix in the future.
It could be the case if the engine power reduced mode is triggered by low transmission fluid.
Second, low engine power can be dangerous in situations like driving on a high-speed highway or freeway.
There are many reasons why your reduced engine power light came on, and we will go over some of them in this article.
This list is by no means exhaustive, and you should take your vehicle to a qualified professional as soon as possible if you are unqualified to diagnose the problem.
Further down the article, we go over some standard OBD2 codes and their meaning.
Modern vehicles are controlled by computer modules that retrieve information from sensors throughout the car.
Wires connect the sensors and computer modules.
A loose connection prevents the computer and sensors from communicating correctly.
A damaged wire can cause a short that will trigger the engine to reduce power mode.
Poor connections and improperly secured ground wires will also cause the engine to throw a code.
Wiring problems can be extremely time-consuming to find.
A proper system scan with an OBD2 sensor can point you in the right direction.
The engine's oxygen sensor measures how much oxygen flows through the vehicle's exhaust system.
It helps the vehicle's computer adjust the intake air-fuel mixture to maximize the engine's efficiency.
A malfunctioning oxygen sensor will send inaccurate information back to the computer, causing your vehicle to run improperly and leading to a reduced engine power warning light.
The computer system is the backbone of a modern vehicle.
It consists of various modules and sensors that send them data working together to keep the vehicle operating as efficiently as possible.
It all happens in real-time with thousands of data points per second.
A failing component in the computer system can lead to countless issues. Any of which can trigger the engine power reduced mode.
A bad mass air flow sensor measures the pressure and density of the air that enters the engine.
This data aids the computer in maintaining the proper air-fuel mixture.
The catalytic converter is part of the vehicle's exhaust system.
The catalytic converter converts toxic exhaust gasses into somewhat less poisonous gasses.
Over time the catalytic converter can become clogged and stop functioning correctly.
It may prevent the vehicle from passing emissions and trigger a warning light.
Problems with the transmission, such as a low fluid level or a clogged transmission oil filter, can put the vehicle in reduced engine power mode.
It is to minimize severe transmission damage if the transmission starves of oil at full speed.
Vehicles such as the GMC Yukon and Chevy Malibu may have to go through an engine relearn process when maintenance such as cleaning or replacing the throttle body has been performed.
If an idle relearn process is not performed, the vehicle may enter reduced engine power mode.
If a vehicle's engine starts to overheat, the car may enter reduced engine power mode to prevent the engine from revving too high and further exacerbating the problem.
The foot pedal uses sensors to measure its relative position.
The vehicle's computer uses this data to calculate the desired throttle response from the vehicle's engine.
A failed pedal position sensor will put the vehicle into reduced engine mode.
It is improbable that needing an oil change is the cause of a reduced engine power warning.
Faulty spark plugs can trigger reduced engine power mode.
Spark plugs are a critical part of your vehicle's ignition system, and if one or more is not working correctly, it could put your car in reduced power mode.
The best place to start first is to do a diagnostic test with an OBD2 scanner.
The OBD2 tool pulls the trouble codes from your vehicle's system and displays them on its screen.
OBD2 scanners can be pretty inexpensive and can save you time and money from "throwing parts" at the problem in hopes of fixing it.
BONUS: It's also nice to mention to a mechanic, who is perhaps a bit unscrupulous, that you have the trouble code to prevent him from trying to give you the "runaround."
As mentioned above, the best place to start is with an OBD2 scanner.
A basic one is inexpensive and can point you in the right direction.
If the problem is something like a dirty gummed up throttle body or a bad O2 sensor, it can be fixed by yourself with essential hand tools.
Unfortunately, often the problem will be more complicated and should be fixed by a professional mechanic at a licensed automotive repair shop.
Follow your OBD2 tools' instructions to pull the trouble codes from your vehicles.
The codes below are standardized across the automotive industry by the Society Of Automotive Engineers.
|Trouble Code||Trouble Code Meaning|
|P0120||Throttle/Pedal Position Sensor/Switch “A” Circuit|
|P0121||Throttle/Pedal Position Sensor/Switch “A” Circuit Range/Performance|
|P0122||Throttle/Pedal Position Sensor/Switch “A” Circuit Low|
|P0123||Throttle/Pedal Position Sensor/Switch “A” Circuit High|
|P0220||Throttle/Pedal Position Sensor/Switch “B” Circuit|
|P0221||Throttle/Pedal Position Sensor/Switch “B” Circuit Range/Performance|
|P0222||Throttle/Pedal Position Sensor/Switch “B” Circuit Low|
|P0223||Throttle/Pedal Position Sensor/Switch “B” Circuit High|
|P0638||Throttle Actuator Control Range/Performance||P0639||Throttle Actuator Control Range/Performance|
|P2100||Throttle Actuator Control Motor Circuit/Open|
|P2101||Throttle Actuator Control Motor Circuit/Open|
|P2105||Throttle Actuator Control System - Forced Engine Shutdown|
|P2119||Throttle Actuator Control Throttle Body Range/Performance|
|P2120||Throttle/Pedal Position Sensor/Switch “D” Circuit|
|P2122||Throttle/Pedal Position Sensor/Switch “D” Circuit Low Input|
|P2123||Throttle/Pedal Position Sensor/Switch “D” Intermittent|
|P2125||Throttle/Pedal Position Sensor/Switch “E” Circuit|
|P2127||Throttle/Pedal Position Sensor/Switch “E” Circuit Low Input|
|P2128||Throttle/Pedal Position Sensor/Switch “E” Circuit High Input|
|P2135||Throttle/Pedal Position Sensor/Switch “A”/”B” Battery Correlation|
|P2138||Throttle/Pedal Position Sensor/Switch “D”/”E” Battery Correlation|
|P2176||Throttle Actuator Control System - Idle Position Not Learned|
The cost to fix engine power reduced mode can vary greatly depending on the problem. For example, a loose connection may cost $0, while a lousy transmission can cost over $3000.
There is no need to panic when the reduced engine power light comes on. But it is crucial to get your vehicle to a mechanic as soon as possible.
There are quite a few reasons why the reduced engine power light is showing, ranging from loose wires to a bad transmission.