When your 2022 Nissan Altima displays an accelerator pedal position sensor fault and sets code P2122, the ECM has detected that APP Sensor 1 is producing a voltage signal lower than expected. This condition affects throttle response and can put the vehicle into a failsafe mode.
Nissan's Electronic Throttle System
The Altima uses Nissan's electronic throttle control system with dual accelerator pedal sensors. P2122 specifically targets Sensor 1 (also called Sensor D in generic terms), indicating its voltage has dropped below the acceptable threshold. This could mean the sensor is reading too low at any point in its travel range.
What Causes the Low Voltage Fault
P2122 in the Altima typically stems from: a failing accelerator pedal sensor with worn resistive element, an open or high-resistance condition in the sensor signal wire, lost 5V reference voltage to the sensor, poor ground connection, or contamination inside the pedal assembly. Aftermarket floor mats restricting pedal travel can also contribute.
Symptoms of APP Sensor Failure
Along with the check engine light, you may experience: sluggish or delayed acceleration, the engine not responding to pedal input, reduced power mode activation, rough idle, or the car not exceeding certain speeds due to limp mode. Some owners report the issue appears worse when the vehicle is cold.
Diagnosis Steps
Using a Nissan Consult or equivalent scanner, technicians monitor APP Sensor 1 voltage. It should read approximately 0.5V with the pedal released and increase smoothly to around 4.5V at full throttle. Flat spots, dropouts, or failure to reach proper voltage indicates sensor failure.
Repair and Replacement
The accelerator pedal assembly requires replacement when internal sensors fail. Nissan's assembly is a complete unit including both sensors. After installation, most Altimas self-calibrate during the first drive cycle, though a manual accelerator pedal release position learning procedure may be needed using the scan tool.