Code Definition

P1234 — TPSS signal error - sensor 2

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Mercedes-Benz

About P1234

P1234 is a manufacturer-specific powertrain diagnostic trouble code recorded for Mercedes-Benz vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1234 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.

P1234 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 DTC is set when the ECM detects an invalid, intermittent, or implausible signal from Throttle Position Sensor 2 (TPSS2). The ECM uses redundant throttle position sensors to monitor the position of the throttle valve. Sensor 2 provides a secondary input to ensure system reliability. If the signal from TPSS2 deviates beyond a calibrated range, becomes erratic, or disagrees with Sensor 1, the ECM logs this fault to indicate a potential failure in the throttle monitoring system. Symptoms can include reduced power or limp mode, erratic idle, hesitation, and an illuminated warning light.

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