Pedal Demand Sensor B Circuit High Input
The accelerator pedal position sensor is sending a signal that's too high, like a volume knob stuck near maximum. The engine control unit thinks you're demanding more throttle than physically possible.
The ECU monitors the pedal demand sensor's voltage output to determine throttle intent. The sensor should produce a proportional voltage between 0.5V and 4.5V based on pedal position. A high input fault occurs when the voltage exceeds the maximum calibrated threshold, indicating either a sensor malfunction or wiring short to power.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Pedal Demand Voltage | 0.5V to 4.5V (proportional to pedal travel) | > 4.8V or stuck high |
| Signal Plausibility | Smooth voltage ramp with pedal movement | Abrupt spikes or constant maximum voltage |
Code P1228 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, P1228 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.