Code Definition

P1129 — Electric Throttle Control System

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

About P1129

P1129 is a manufacturer-specific powertrain diagnostic trouble code recorded for Lexus vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

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.

P1129 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

The Electric Throttle Control System on this Lexus replaces the mechanical throttle cable with an Engine Control Module (ECM) controlled throttle body that positions the throttle plate based on accelerator pedal demand. DTC P1129 is a system level code that sets when the ECM detects a malfunction in the overall electric throttle control system that prevents normal throttle operation, such as a loss of correlation between commanded and actual throttle position or an internal control fault. It can be triggered by faults in the throttle actuator, the position sensors, the pedal sensor, the wiring...

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