P2129: Throttle/Pedal Position Sensor/Switch E Circuit Intermittent

What does P2129 mean?

P2129 is meant for short dropouts or spikes in signal circuit E that do not last long enough for a steady low or high fault. No manufacturer documents this code publicly. GM and Ford, which assign E to the second pedal sensor, catch such glitches inside their circuit codes instead: GM counts failures every 12.5 ms and flags the APP sensor 2 circuit after 19 of 39 counts (P2125/P2127/P2128), Ford uses 0.25/4.75 V limits. CARB requires circuit monitoring of input sensors; the code fits that duty. Check for loose pins and harness chafing with the pedal moved slowly. Effects range from a warning lamp to brief power cuts while driving.

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

Symptoms

• Warning lamp that comes and goes
• Brief hesitation or power loss while driving
• Reduced power mode after repeated dropouts

Common causes

• High Loose terminal or poor pin tension at the pedal connector
• Medium Chafed harness making intermittent contact
• Medium Worn spot or cracked joint inside the pedal sensor

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