OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P2121

Throttle/Pedal Position Sensor "C" Range/Performance

The "C" channel of the throttle or pedal sensor produces an electrically valid signal that does not match the other channels or the operating point.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number1 / 21

Possible causes

  • Sensor track C worn high
  • Correlation with tracks A/B lost medium
  • Sensor element aged beyond calibration window low

Symptoms

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

Inspection / repair

  • Difficulty: easy
  • DIY: possible
  • Estimated cost: 80–400 €
  • Estimated time: 0.3–1.5 h
  • Component: accelerator pedal sensor
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication