My GMC Acadia is going into engine power reduced mode

Unless you have specific error codes for initial reference, second guessing on parts can get expensive. Although AI generated, EFI systems issues can use AI help but require more than casual knowledge of diagnosing/troubleshooting/repair of EFI systems to correlate Ai generated info against known information. The following AI generated guide may help;

Various sensors in a GMC Acadia can trigger the "Reduced Power Mode," also known as limp mode, to protect the engine when a critical component malfunctions. The most common sensor-related culprits involve the electronic throttle control system and air/fuel mixture monitoring.

Throttle control system sensors

The Acadia's electronic throttle control (ETC) system uses multiple sensors to regulate engine speed. A discrepancy in their readings will signal a problem and force the vehicle into reduced power mode.

• Throttle Position Sensor (TPS): This sensor tracks the position of the throttle blade inside the throttle body. The system uses two TPS sensors, and if their readings don't match, it can trigger reduced power mode.
• Accelerator Pedal Position (APP) Sensor: This sensor is located on the accelerator pedal and measures how far down the driver is pressing it. It's an important part of the ETC system, and any malfunction can activate limp mode.

Air and fuel management sensors

These sensors ensure the engine receives the proper air-to-fuel ratio for optimal performance. Any issues here can cause the engine control unit (ECU) to limit power.

• Mass Air Flow (MAF) Sensor: Measures the amount of air entering the engine. If the sensor is dirty or faulty, the ECU may receive incorrect readings and restrict power.
• Oxygen (O2) Sensors: Monitor the amount of oxygen in the exhaust to regulate the air-fuel mixture. A malfunctioning O2 sensor can cause the mixture to be too rich or too lean, resulting in reduced power.
• Fuel Pressure Sensor: A sensor on the fuel rail that can trigger reduced power mode if it detects lower than expected fuel pressure. This can be a symptom of a faulty fuel pump or a clogged fuel filter.

Engine condition sensors

The vehicle's computer also monitors the engine's internal condition. If a severe problem is detected, it will initiate reduced power mode to prevent catastrophic failure.

• Crankshaft Position Sensor: Provides the ECU with engine speed and position information. If this sensor fails, it can cause the engine to shut down or trigger reduced power mode.
• Knock Sensors: These sensors detect engine knocking or pinging. In some cases, a knock sensor can trigger reduced power mode if the ECU detects engine timing issues, which could be related to low fuel pressure.
• Engine Temperature Sensors: If the engine begins to overheat due to a cooling system issue, the ECU can enter reduced power mode to protect the engine from further damage.

How to diagnose the problem

When your Acadia enters reduced power mode, the best course of action is to have the diagnostic trouble codes (DTCs) read with an OBD-II scanner. The stored codes will point to the specific sensor or system that is causing the problem and guide you toward a proper diagnosis and repair.