A completely dead gas pedal on your 2020 Chevrolet Silverado is alarming, especially when you press down and nothing happens. Code P2138 points to an accelerator pedal position sensor D/E voltage correlation problem that's causing the electronic throttle control system to shut down throttle response.
Why the Pedal Goes Dead
The 2020 Silverado's drive-by-wire system relies on two APP sensors working in harmony. When they disagree beyond a certain threshold, GM's safety programming assumes a malfunction and cuts throttle response rather than risk unintended acceleration. P2138 specifically indicates sensors D and E aren't tracking together as they should.
Root Causes of the Problem
This dead pedal condition commonly results from: internal failure of the accelerator pedal position sensor assembly, water damage to the pedal assembly or connector from wet floor mats or leaking windshield seals, damaged wiring in the harness run, or connector corrosion from road salt exposure. The 5.3L, 6.2L, and diesel models all use similar APP sensor setups.
Warning Signs Before Total Failure
Most owners experience warning signs before the pedal goes completely dead: momentary hesitation when pressing the gas, intermittent dead spots in pedal travel, the reduced engine power message appearing, or the service stabilitrak warning. The check engine light typically illuminates before complete failure.
Diagnostic Approach
Technicians will monitor both APP sensor voltages using a scan tool. At rest, Sensor D typically reads about 0.7V and Sensor E reads about 0.3V (they operate on different voltage ranges). As the pedal moves, both should change proportionally. Any deviation, flat spot, or erratic movement indicates sensor failure.
Getting Your Truck Running Again
The accelerator pedal assembly replacement is the standard fix. GM's part includes both sensors pre-calibrated. After installation, the throttle system needs to relearn idle and throttle positions through a specific procedure or short drive cycle. Some Silverados may need a PCM flash update if the issue was related to a calibration problem.