Vehicle
Subaru Forester 2004 EJ25 turbo series 1.
Symptom
Running poorly. Clearing throttle-related codes bought a short window of driving before limp mode returned. Stored code: P2109 — Throttle / Pedal Position Sensor A Minimum Stop Performance — would not clear.
Diagnosis
Scope checks showed power and a normal TPS reading, but no ECU drive to the throttle actuator motor. Wiring diagrams show the ECU needs inputs (including the throttle-control relay) before it will duty-cycle the actuator — “before you can get an output you must have an input.”
On ignition cycle the ECU briefly energised the throttle relay then shut it down. A new relay did not fix it. Wiring from ECU to actuator was checked for shorts to ground — integrity OK — so attention moved to the ECU.
Repair
Replacement ECU of the same part number, programmed on the vehicle. After programming the throttle actuator operated, codes were cleared, and a road test confirmed the repair.
Summary
Prove power, inputs, wiring and actuator resistance before condemning the ECU — then match part numbers when programming.
Book in
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