DTC P0503: Vehicle Speed Sensor (VSS) A Intermittent/Erratic/High

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2011 Mercury Milan, 2011 Mercury Mariner, 2011 Mercury Grand Marquis, 2011 Lincoln Town Car, and 2011 Lincoln Navigator L. However, it is still accessible from the selected car via links, so may be relevant.

P0503 - VEHICLE SPEED SENSOR (VSS) A INTERMITTENT/ERRATIC/HIGH

Description:	Indicates incorrect or noisy VSS performance. Vehicle speed data is received from either the VSS, the transfer case speed sensor (TCSS), or the anti-lock brake system (ABS) control module.
Possible Causes:	Noisy VSS or TCSS input signal from radio frequency interference or electromagnetic interference external sources, such as ignition components or the charging circuit Damaged VSS or driven gears Damaged TCSS Damaged wiring harness or connectors Concern in the modules or circuits connected to the VSS or TCSS circuit Aftermarket add-on
Diagnostic Aids:	Monitor the VSS PID while driving the vehicle, and check for intermittent vehicle speed indication. Verify the ignition and charging systems are functioning correctly.
Application	Key On Engine Off	Key On Engine Running	Continuous Memory
F-Series Super Duty	GO to PINPOINT TEST DF .
Manual Transmission	GO to PINPOINT TEST DP .
All others	The powertrain control module (PCM) uses information from the ABS control module and the transmission control module (TCM) to calculate vehicle speed. Check these modules for DTCs.