Code Definition

P1121 — Throttle Position Sensor Signal Malfunction from ECM to TCM

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

About P1121

P1121 is a manufacturer-specific powertrain diagnostic trouble code recorded for Kia 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 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

The Engine Control Module (ECM) reads the Throttle Position Sensor (TPS) and transmits the throttle angle value to the Transmission Control Module (TCM), which uses it to schedule gear changes, line pressure, and torque converter clutch lockup. DTC P1121 is set when the TCM determines that the throttle position signal arriving from the ECM is missing, out of range, or does not correlate with other engine data. On many Kia models this value is shared over the internal communication line between the two controllers, so the fault can lie in the TPS itself, in the ECM processing, or in the link be...

Join TaT to view the complete code information and diagnostic details.

Quick Facts