Code Definition

P2128 — Throttle / Pedal Position Sensor / Switch E Circuit High Input

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Toyota

About P2128

P2128 is a generic (obd-ii standard) powertrain diagnostic trouble code recorded for Toyota vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P2128 is stored, the module has detected a signal or supply voltage higher than the expected operating range; and a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P2128 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The engine control module (ECM) sets P2128 when it detects a high voltage condition in the Throttle/Pedal Position Sensor (TPS/APP) 'E' circuit. This occurs when the signal voltage from the sensor is higher than the expected range for a predetermined period, which may indicate a short to power, a stuck sensor, or a wiring issue. The ECM relies on this signal to determine throttle or accelerator pedal position for engine management.

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