Code Definition

P1121 — Throttle Position lower than expected

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

About P1121

P1121 is a manufacturer-specific powertrain diagnostic trouble code recorded for Acura vehicles. 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 lower than the expected operating range.

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

During electronic throttle control (ETCS) operation the Engine Control Module (ECM) commands the throttle motor to a target plate angle and confirms the result through throttle position sensors 1 and 2. DTC P1121 is stored when the ECM detects that the actual throttle position stays consistently lower than the commanded opening, meaning the plate is not following the control signal. This usually points to a mechanical restriction such as carbon buildup, a weak or binding throttle motor, or a sensor calibration problem rather than a wiring open. The condition must persist for a calibrated durat...

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