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

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.

High severity. Can I keep driving?Be careful: the car may suddenly lose power. If it goes into limp mode, get off the highway and calmly make your way to a repair shop.

Symptoms

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

Most likely causes

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

What to check, in order

Start with the simplest. You can tick off each step.

Check the pedal and throttle connectors
Gently move the wiring with the engine running and watch whether the reading changes.
Use live data to confirm that both sensors rise smoothly and consistently
Clean the throttle if it has carbon buildup
Run the relearn procedure with the scanner if the manufacturer requires it
Replace the part identified by the diagnosis

Good to know

Repair difficulty: medium
It can trigger limp mode.
It affects emissions.

What each character of P2129 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
1: Air and fuel
29: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2129?

Be careful: the car may suddenly lose power. If it goes into limp mode, get off the highway and calmly make your way to a repair shop.

What causes code P2129?

The most common causes are: loose terminal or poor pin tension at the pedal connector; chafed harness making intermittent contact; worn spot or cracked joint inside the pedal sensor.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.