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

P2621

Throttle Position Output Circuit Low

The buffered throttle position output that the engine controller sends to the transmission and body modules is below the expected level. Usually a short to ground or a failed output stage.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number6 / 21

Possible causes

  • Output wire shorted to ground high
  • Output buffer transistor failed medium
  • Connector pins corroded - high contact resistance low

Symptoms

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

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 120–800 €
  • Estimated time: 0.8–3 h
  • Component: control module
  • Component: signal output buffer
  • Component: wiring harness
  • MIL / check engine light

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