What Does P1257 Mean?
The ECM has detected an abnormally high correlation error between Pedal Demand Sensor 1 (PDS1) and the Learned Pedal Demand Sensor (LPDS). This means the primary accelerator pedal position signal and the learned reference value diverge significantly at higher pedal positions. The electronic throttle control system will likely enter a failsafe reduced-power mode to prevent unintended acceleration.
Safety Warning
This is a safety-critical code involving the primary throttle demand sensor. Signal disagreement can result in sudden reduced power mode while driving, which is dangerous in traffic. In worst-case scenarios, throttle control anomalies could lead to unintended acceleration. Immediate diagnosis is strongly recommended.
Common Causes
35%
Failing accelerator pedal position sensor assembly with worn resistive track on sensor 1
25%
Corroded or damaged connector pins at the accelerator pedal module
20%
High resistance or intermittent connection in PDS1 signal wiring
10%
Mechanical restriction of the accelerator pedal preventing full travel
10%
ECM needs recalibration or software update for pedal learning
Diagnostic Steps
1
Check for related pedal position codes (P1254, P2122-P2128, P2138) to determine the scope of the fault.
2
Verify the accelerator pedal has full mechanical travel with no binding, sticking, or interference from floor mats or trim panels.
3
Monitor PDS1, PDS2, and LPDS live data on a scan tool while slowly and smoothly sweeping the pedal through its full range — note any jumps, dropouts, or divergence.
4
Inspect the accelerator pedal connector and harness for corrosion, water damage, or chafed wires.
5
If PDS1 signal is erratic while PDS2 tracks normally, replace the accelerator pedal assembly.
6
After replacement, perform the accelerator pedal relearn procedure per manufacturer instructions.
Estimated Repair Cost
$150 - $500
Parts + labor, varies by vehicle and location
The ECM has detected an abnormally high correlation error between Pedal Demand Sensor 1 (PDS1) and the Learned Pedal Demand Sensor (LPDS). This means the primary accelerator pedal position signal and the learned reference value diverge significantly at higher pedal positions. The electronic throttle...
The most common cause of P1257 (Pedal Correlation PDS1 and LPDS High) is: Failing accelerator pedal position sensor assembly with worn resistive track on sensor 1
Typical repair costs for P1257 range from $150 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This is a safety-critical code involving the primary throttle demand sensor. Signal disagreement can result in sudden reduced power mode while driving, which is dangerous in traffic. In worst-case scenarios, throttle control anomalies could lead to unintended acceleration. Immediate diagnosis is strongly recommended.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1257 to identify the root cause.
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Powertrain
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Electronic Throttle Control
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