Code Definition

P1121 — Throttle Position (TP) Sensor Circuit Intermittent High Voltage

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Generic

About P1121

P1121 is a manufacturer-specific powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1121 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.

P1121 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

This fault code is set when the Powertrain Control Module (PCM) detects an intermittent high voltage signal from the Throttle Position (TP) sensor. The TP sensor monitors throttle movement and position, providing critical input for fuel delivery, ignition timing, and transmission shifting. A high voltage reading suggests the sensor is reporting a throttle angle higher than expected, which can cause drivability issues such as rough idling, hesitation, or poor acceleration.

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