P2166: Throttle/Pedal Position Sensor D Maximum Stop Performance

What does P2166 mean?

P2166 refers to position signal D, which on Ford designs is the first track of the accelerator pedal. The code means the reading with the pedal pressed all the way does not match the calibrated maximum, for instance because the pedal never reaches its stop or the track is worn at the far end. No manufacturer documents P2166 publicly; it applies the logic of the A version P2163 and of the open-stop learning in a Visteon patent to the pedal. A thick floor mat, a bent pedal arm or a worn pedal module are typical causes. The engine computer may then cap the torque request, so the car feels as if it never reaches full power. P2115 covers the rest position of D, P2120-P2124 its circuit, and P2138 the D/E correlation.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Engine warning lamp on
• No kickdown or no full power with the pedal floored
• Possible limp mode

Common causes

• High Floor mat or object keeps the pedal from its stop
• Medium Pedal sensor track D worn at full travel
• Low Bent pedal arm or damaged pedal bracket
• Low Corroded pedal connector shifting signal D

Likelihood is a general estimate across vehicles; your make and model may differ.