P2128
Throttle/Pedal Position Sensor/Switch E Circuit High Input
When a vehicle powertrain module registers the fault code P2128, it points directly to an internal system malfunction identified as "Throttle/Pedal Position Sensor/Switch E Circuit High Input". Operating your engine under this condition may degrade long-term fuel maps.
Driver's Summary
Storing code P2128 is your car's way of telling you something is wrong with the throttle/pedal position sensor/switch e circuit high input. You may notice no throttle response, engine stays at idle, check engine light, all of which are direct consequences of this malfunction. Stop driving as soon as it is safe to do so. This fault can lead to expensive secondary damage if left unaddressed.
Symptoms
No throttle response, engine stays at idle, check engine light
Common Causes
- Short to voltage in APP sensor E circuit
- Failed accelerator pedal assembly
- Broken sensor ground wire
- PCM fault
How to Fix
- 1 Repair wiring short to power
- 2 Replace accelerator pedal
- 3 Repair broken ground wire
- 4 Test PCM
Technical Explanation
To set P2128, the PCM samples the affected circuit multiple times per second, comparing live readings against manufacturer-programmed operating windows. A two-trip detection strategy is employed for most powertrain codes: the fault must be detected on one drive cycle, the vehicle key-cycled off, and the fault detected again on the next drive cycle before the MIL illuminates and a permanent DTC is stored. After two failed drive cycles, the code transitions from a pending to a confirmed DTC, and the PCM activates the MIL. Clearing the code without repairing the fault will result in re-illumination within one to two complete drive cycles.
Is It Safe to Drive?
This fault carries real mechanical risk. The root causes — including short to voltage in app sensor e circuit — can trigger a chain reaction of component failures if the vehicle continues to be driven. Have it towed or drive directly to a shop without delay.
Mechanic's Pro Tip
The most common mistake with P2128 is replacing the sensor without verifying the reference voltage and ground integrity first. Use a scan tool to monitor the sensor's live output; a truly failed sensor shows a stuck, flatlined reading — a sensor that fluctuates but reads slightly off usually indicates a wiring or vacuum issue, not a dead sensor. Always spray electrical contact cleaner on the connector pins before condemning the sensor.
Pedal assembly: $150 - $350