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P0120 Powertrain

Throttle Position Sensor / Switch A Circuit Malfunction

The ECU detects a general electrical fault on the throttle position sensor/switch A circuit. Signal missing, implausible, or wiring broken. Generic catch-all when no more specific TPS-A code applies.

Affected components

  • Throttle position sensor
  • Tps wiring
  • Tps connector
  • Throttle body

Common causes

  • High likelihood: TPS worn or failed (dead spot in resistive track)
  • Medium likelihood: TPS wiring or connector fault
  • Low likelihood: TPS mechanically misaligned to throttle shaft

Possible symptoms

  • Check engine light on
  • Reduced throttle response, possible limp mode
  • Hesitation or surging
  • Idle too high or too low

Diagnostic notes

  • The malfunction indicator lamp may illuminate
  • This code can affect emissions
  • A drive cycle may be required after repair
  • Reduced-power or limp mode may occur

Sources

Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.

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