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DTC codes / Ford codes / P1257

P1257 · FordPedal Correlation PDS2 and HPDS

P1257 on Ford vehicles means the powertrain control module (PCM) has detected a disagreement between the two independent accelerator pedal position signals, specifically the Pedal Demand Sensor 2 (PDS2) and the High-resolution Pedal Demand Sensor (HPDS). The PCM compares these two voltages as a cross-check, and when they fall outside the expected correlation window for a calibrated period, it stores this code and typically illuminates the wrench or check engine light.

SystemPowertrain
Code typeFord specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering (injector circuits)

Symptoms you may notice

  • Wrench or check engine light illuminated on the instrument cluster
  • Reduced engine power or limp-home mode with limited throttle response
  • Hesitation or stumble when pressing the accelerator pedal
  • Inconsistent or surging engine speed despite steady pedal input
  • Often no symptoms besides the warning light, especially if the fault is intermittent
  • Cruise control may become inoperative or disengage unexpectedly

Common causes, most likely first

  1. Worn or contaminated accelerator pedal position sensor tracks inside the pedal assembly
  2. Corroded, backed-out, or chafed wiring at the pedal connector or along the harness
  3. Poor electrical ground for the pedal sensor reference circuit
  4. Water intrusion into the pedal connector or footwell area causing signal drift
  5. PCM software calibration issue or internal PCM fault affecting signal processing
  6. Aftermarket floor mats or debris obstructing full pedal travel and skewing sensor readings

How to diagnose and fix it

  1. Inspect the accelerator pedal assembly and connector for physical damage, debris, or aftermarket floor mat interference
  2. Check for stored freeze-frame data and run a key-on, engine-off pedal sweep while watching both PDS2 and HPDS voltages on a scan tool
  3. Measure reference voltage, ground, and signal return at the pedal connector with a multimeter and compare to Ford specifications
  4. Perform a wiggle test on the pedal harness and connector while monitoring signal voltages to expose intermittent wiring faults
  5. Clean or repair corroded terminals and re-seat the connector, then clear the code and verify correlation during a road test
  6. If signals remain inconsistent, replace the accelerator pedal assembly with a Ford-quality unit and relearn the pedal position
  7. Check for PCM calibration updates or, as a last resort, diagnose the PCM itself if all inputs and wiring test good

Pedal correlation faults that fool good technicians

  • A loose or aftermarket floor mat that limits pedal travel can set P1257 without any electrical fault, so always check pedal free movement before condemning sensors.
  • The two pedal signals are not identical voltages; they are scaled differently by design, and technicians who expect equal readings will misdiagnose a healthy pedal.
  • Intermittent P1257 codes often trace to a chafed wire in the footwell harness rather than the pedal sensor itself, so a wiggle test with a scan tool connected is essential.
  • Water leaks from a clogged cowl drain or damaged windshield seal can corrode the pedal connector and cause signal drift that only appears in damp weather.
  • This code does not always mean the pedal assembly is bad; a poor chassis ground shared with other sensors can pull the reference voltage down and trigger the correlation fault.

Can I keep driving with P1257?

You can usually drive the vehicle to a repair shop, but expect reduced power and avoid heavy throttle or highway merging until the fault is repaired. If the vehicle enters limp-home mode or the pedal response becomes erratic, stop driving and arrange a tow.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Ford vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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