P2128 — Throttle/Pedal Position Sensor/Switch E Circuit High Input
Moderate severityWhat it means
P2128 is stored when the engine control unit sees a fault involving accelerator pedal position sensor E. Sensor E is the redundant accelerator-pedal position signal that the control unit cross-checks against sensor D for safety in a drive-by-wire system. A “high” reading means the signal is pinned near the top of its range — often an open circuit, a lost ground, or a short to voltage.
Common symptoms
- The live reading sits abnormally high or maxed out
- Reduced power or limp mode
- Hesitation or poor throttle response
- Unstable idle
Likely causes
- Open signal or ground wire
- Signal wire shorted to a voltage supply
- A worn accelerator pedal position sensor
- A connector or wiring fault on the E circuit
What to check first
- Check for an open circuit or missing ground at the sensor connector
- Compare sensor D and E signals in live data — they should track together
- Inspect the pedal connector and wiring
Can you keep driving?
Because E is a safety-redundant signal, the car usually drops to reduced power; have it checked promptly.
Frequently asked questions
What is the most common cause of P2128?
The most likely cause is: Open signal or ground wire. Several other faults can set P2128 as well, so confirm the real cause with live data and the checks above before replacing any parts.
Can I just clear P2128 and keep driving?
Clearing P2128 with an OBD2 scanner turns the warning light off, but if the underlying fault has not been repaired the code will usually come back within a few drive cycles. Fix the cause first, then clear the code to confirm the repair worked.
How serious is P2128?
P2128 is a moderate-severity code. The car is often still drivable, but have it diagnosed soon — the underlying problem can get worse and it may fail an emissions test.
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All information, explanations and guidance on this page are general preliminary information only. They are estimates and may be entirely wrong, incomplete or inaccurate, or may not apply to your vehicle at all. Never take any action based on this content alone — do not decide to keep driving, clear codes, replace parts, repair or otherwise work on your vehicle based only on what you read here. In every case, and for any final decision, you must consult qualified technical personnel (a professional mechanic, an authorized service centre or an engineer) and obtain their approval before acting. MechanicAI accepts no liability or responsibility whatsoever for any damage, fault, injury, loss or outcome that may arise — directly or indirectly — from using or relying on this information, for any reason and under any circumstances. By using this page you acknowledge and accept these terms.