P0503 OBD-II Trouble Code: Vehicle Speed Sensor Intermittent/Erratic/High

P0503 code definition

Vehicle Speed Sensor Intermittent/Erratic/High

What the P0503 code means

The P0503 code indicates that the Engine Control Module (ECM) has detected an inconsistent signal voltage from the vehicle speed sensor.

What are the causes of the P0503 code?

• A faulty vehicle speed sensor
• Damaged wiring or connectors in the vehicle speed sensor circuit
• Multiple faulty wheel speed sensors/ hub bearings
• Broken ABS tone rings
• A faulty ECM
• Incorrect size wheels or tires
• A faulty instrument cluster

What are the symptoms of the P0503 code?

• Check Engine Light illumination
• Speedometer needle may bounce up and down
• Inaccurate speedometer

How does a mechanic diagnose the P0503 code?

• Makes sure that the correct wheels and tires are installed

• Locates the vehicle speed sensor then checks the connectors and the wiring in the circuit

If all is well so far:

• Tests the vehicle speed sensor for faults using the manufacturer’s recommended procedure

In the unlikely event that the issue has not been found yet:

• Inspects the wheel speed sensors
• Inspects the tone rings
• Inspects the wheels and tires
• Inspects the ECM for faults

If any issues were found during the diagnosis of this issue, the parts would be replaced at the customer’s request.

Common mistakes when diagnosing the P0503 code

A common mistake that could be made when diagnosing the P0503 trouble code would be overlooking the obvious. Checking the wheels and tires for correct size is the first thing that should be done considering that it is a visual check and requires no tools other than your eyes.

How serious is the P0503 code?

The P0503 trouble code is not too serious. This code only affects the performance of the vehicle’s speedometer. The only issue that may occur while having a P0503 code would be a speeding ticket.

What repairs can fix the P0503 code?

• Replacing the speed sensor
• Repairing or replacing wiring or connectors in the speed sensor circuit
• Replacing one or more wheel speed sensors
• Replacing a hub bearing
• Replacing a CV axle due to a faulty tone ring
• Replacing the ECM
• Replacing the instrument cluster
• Fitting the correct size wheels and tires to the vehicle

Additional comments regarding the P0503 code?

If a P0503 trouble code is stored in your vehicle, it would be wise to drive slightly slower than the rest of traffic to ensure that you are not speeding until the issue has been resolved.

Need help with a P0503 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.