Pedal Position Sensor C Circuit High Input
The gas pedal sensor is sending a voltage signal that's too high to the engine computer, like a volume knob stuck at maximum instead of responding to your touch. The ECU can't properly interpret your throttle input and triggers this fault code.
The ECU monitors the pedal position sensor's voltage output as you press the accelerator. The sensor should produce a voltage between 0.5V and 4.5V depending on pedal position. When the voltage exceeds the maximum threshold, the ECU detects a high input fault and cannot safely control throttle response.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Pedal Position Voltage | 0.5V to 4.5V (varying with pedal angle) | Above 4.8V or stuck at maximum |
| Sensor Circuit Resistance | 500Ω to 100kΩ (depending on position) | Open circuit or extremely low resistance |
Code P1221 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P1221 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.