OBD-II code · Powertrain (generic, extended)

P2104 Throttle Actuator Control System — Forced Idle

The ECU has detected a fault severe enough that it forces the throttle actuator to the idle stop. The driver loses pedal authority — only idle is available until the underlying TAC fault clears.

Is it safe to drive with P2104?

The car may go into limp mode (reduced power). Get it diagnosed before a long trip.

Common causes

  • Most likelySevere upstream TAC fault
  • PossibleThrottle position signal invalid

Symptoms

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

Repair at a glance

Difficulty
Hard
DIY friendly
Best left to a mechanic
Typical labour
1–4 h
Emissions test
Likely to fail
After the fix
A drive cycle is needed before the light stays off
Parts involved
Throttle Actuator Control, Ecm

Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.