P1254: Pedal Correlation PDS2 and LPDS High

P1254 is a pedal demand sensor correlation fault. Modern drive-by-wire vehicles use two or more independent sensors on the accelerator pedal assembly -- if any pair of sensors disagrees significantly, or if both read outside their expected range at the same time, the ECM flags it. P1254 specifically relates to PDS2 (Pedal Demand Sensor 2) and LPDS (Lower Pedal Demand Sensor) both reading high, which the ECM interprets as a potential runaway throttle condition and responds by limiting engine output.

When the ECM can't trust the throttle input signal, it typically enters a reduced-power or limp-home mode -- the car will drive but won't accelerate normally. This is a deliberate safety response to an ambiguous throttle command. The pedal position sensor (PPS) assembly is the most common failure point: the resistive tracks inside the sensor wear over time, especially in stop-start city driving, and can produce out-of-range readings even when the pedal itself moves freely.

Before condemning the sensor assembly, check the pedal connector and wiring harness for corrosion or damage -- particularly the reference voltage supply and ground circuits, since a supply voltage fault can force both sensors high simultaneously. If the wiring checks out, the PPS assembly (which typically houses both sensors in a single unit) is almost always the repair. This is a dealer or specialist job on most vehicles given the safety implications.