How to fix a reduced engine power message
Reduced Engine Power in GM Vehicles: Understanding the Warning Message and Its Causes
If you own a General Motors (GM) vehicle, you may have encountered the dreaded “Engine Power Reduced” message on your dashboard. This warning can be alarming, especially if unfamiliar with its implications. In this article, we’ll delve into what this message means, explore its most common causes, and discuss potential solutions to help you get back on the road with confidence.
What Does The Reduced Engine Power Message Mean?
The Reduced Engine Power message is part of GM’s engine protection system. When your vehicle’s computer detects a problem that could potentially damage the engine if left unchecked, it activates this safety feature. The system deliberately limits the engine’s power output to prevent further damage and allow you to safely drive to a service center or home.
When reduced engine power mode is activated, you may notice these symptoms:
• Significant reduction in acceleration
• Limited top speed (usually around 35-45 mph)
• Rough or unstable idle
• Illuminated check engine light
The Most Common Causes of a Reduced Engine Power Message
Several issues can trigger the reduced engine power mode in GM vehicles. Here are some of the most frequent culprits:
1) Faulty Electronic Throttle Body— A malfunctioning throttle body can fail to respond properly to driver input, disrupting this airflow, leading to performance issues, and triggering the reduced engine power message. Common symptoms include:
• Uneven or rough idle
• Hesitation during acceleration
• Stalling
2) Problems with the Mass Airflow Sensor— The mass airflow (MAF) sensor measures the amount of air entering the engine. When it fails or becomes dirty, it can send incorrect readings to the engine control module, resulting in poor performance and potentially activating reduced engine power mode. Signs of a faulty MAF sensor include:
• Rough idle
• Difficulty starting the engine
• Poor fuel economy
What to Do When You See the Message
If you encounter the “Reduced Engine Power” message on your GM vehicle:
1) Safely pull over and turn off the engine.
2) Wait a few minutes, then restart the vehicle.
3) If the message clears, drive cautiously and have your vehicle checked as soon as possible.
4) If the message persists, it’s best to have your vehicle towed to a qualified mechanic to prevent further damage.
Diagnostic Process for Reduced Engine Power
• Use a code reader or scan tool to read error codes from the engine control module.
• Refer to a shop manual for the recommended test procedures for the trouble codes.
• Perform the recommended tests to isolate the specific issue causing the reduced engine power warning.
GM service bulletin
GM has issued a service bulletin #22-NA-008 to address a GM reduced engine power message on the vehicles listed below. You may also find the following trouble codes U060F,U1346, P0101, P0102, P1101 AND/OR P14B6 on the vehicles listed below
Code Definitions:
P0101 Code – Mass or Volume Air Flow Circuit Range/Performance Problem
P0102 Code – Mass or Volume Air Flow Circuit Low Input
P1101 Code – Mass Air Flow Sensor Out of Self-Test Range
P14B6 Code – Mass Air Flow Sensor Signal Message Counter Incorrect
U1345 Code – Engine Control Module LIN Bus 1
Vehicles covered by GM #22-NA-008 service bulletin
2020-2022 Buick Encore GX
2021-2022 Chevrolet Trailblaer
Cause of the GM reduced engine power and trouble
The location of the broken wire
GM has determined that the problem may be caused by a broken wire in the wiring harness for the multifunction sensor, circuit 492. A zip tie installed at the factory was pulled too tight, causing the wire to break when the harness flexes.
Fix for the GM reduced engine power message and associated and trouble codes
GM recommends inspecting the 2nd retainer back from the MAF sensor while the engine is running. The wire is most likely broken at or near the zip tie and malfunctions during acceleration. Wiggle or pull on the harness at this point to identify the break in the wire.
Repair the broken wire using a the replacement pigtails listed below and using waterproof connectors. Pay attention to the distance from the fixed clip mounted to the charge air cooler inlet hose to the fixed clip mounted on the air cleaner housing. The distance must be 3.4” to allow for proper flex during acceleration.
Pigtail connector kit
85518225 pigtail kit to fix a GM reduced engine power message
85519071 (LIH) $32.39 from this Chevrolet Dealer
85518225 (L3T) $39.30 from this GM dealer
A service bulletin is not a recall, and the fixes shown are not free.
A service bulletin is issued by a vehicle manufacturer to notify dealers and vehicle owners of a potential issue that may exist in some vehicles. Service bulletins provide recommended actions to address the issue, such as inspections, repairs, or part replacements. Compliance with service bulletins is not mandatory.
An auto recall is an official notice issued when a manufacturer has determined that a vehicle component is defective and poses a safety concern. Recalls are regulated by the National Highway Traffic Safety Administration (NHTSA). When a safety-related defect is identified, the manufacturer must notify NHTSA and vehicle owners. Recalls require the free repair, replacement, or refund of the defective part by authorized dealers. Vehicle owners are legally obligated to comply with recall notices.
While service bulletins may indicate potential problems, recalls denote actual safety hazards confirmed by the manufacturer and NHTSA. Service bulletins provide guidelines for repairs, but recalls necessitate the correction of the defect. Both aim to prevent issues and ensure vehicle safety, but recalls carry more stringent requirements and compliance is mandated by law.
©, 2023 Rick Muscoplat