Code Definition

P1121 — Throttle Position Sensor Signal Not Consistent with Mass Airflow Signal

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

About P1121

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

The Engine Control Module (ECM) continuously cross checks the Throttle Position Sensor (TPS) signal against the Mass Air Flow (MAF) sensor signal to confirm both inputs agree on engine load. DTC P1121 sets when the ECM determines that the throttle opening reported by the TPS does not correspond to the airflow measured by the MAF sensor, indicating one of the signals is implausible. Because both sensors are central to fuel and spark calculation, a mismatch usually points to a sensor, wiring, or air induction fault rather than a single failed part. When this code is stored the driver may notice ...

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