How To Fix P0502 Obd2 Code? Vehicle Speed Sensor Low Input

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How To Fix P0502 Obd2 Code?
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This is a general issue code, which means it applies to any cars produced from 1996 to the present date, especially those which are attached with the OBD-II system such as Cadillac, Chevrolet company, GM, GMC, Saab, Subaru, or Volvos. Of course, specifications on the definition, solving issues, and repairs are different from one make and model to another.

P0502 Meaning:

P0502 Meaning:

The P0502 error code implies that the Engine Control Module (ECM) has identified a different speed reading between the vehicle and wheel speed sensors.

OBD-II Code P0502: Symptoms, Causes & Diagnose


Other than a Check Engine Light and an incorrect speedometer, there should be next to no symptoms connected with this issue code.


  • A defective vehicle speed sensor.
  • Damaged wire or connections in the vehicle speed sensor circuit.
  • Multiple faulty wheel speed sensors/ hub attachments.
  • Broken ABS tone rings.
  • A problematic powertrain control module.
  • Wrong size wheels or tires.
  • A malfunctioning instrument cluster.

How to Diagnose P0502 obd2 code

A malfunctioning vehicle speed sensor almost often causes this error code; therefore, the technician will usually begin by trying to track one down. If the wiring and connectors for the sensors seem to be in excellent shape, the technician will perform the manufacturer-recommended test on the vehicle speed sensor.

In addition, the technician will make sure that all of the wheels and tires are the correct sizes. Tone rings and wheel speed sensors would be checked on all four wheels of the suspension.

Finally, if there are no further faults, the ECM would be checked, and the customer’s requested components would be replaced. Obd2 Scanner With ABS And SRS.

Tools you need:

  • Repair instructions for automobiles.
  • FIXED.
  • Screwdriver.


Diagnostic tools such as an oscilloscope, a diagnostic scanner, and a digital volt/ohmmeter may also be required to diagnose the P0502 code (DVOM) properly.

It is necessary to inspect the vehicle’s wiring, speed sensors, and connections to see any damage before troubleshooting the P0502. Close any open or shorted circuits, and thoroughly clean any metal debris collected on damaged sensors before continuing. While inspecting the sensor, make sure the reactor ring is in good working order.

Use a scan tool to get all DTCs and freeze frame data recorded on the computer by scanning the automobile diagnostic port. Take time to write down this information before resetting the codes if you need it in the future.

Locate the Technical Service Bulletins necessary for the vehicle using the vehicle’s data source (TSB). The diagnostic information that matches the symptoms and stored codes of the car in issue may be available from a Technical Service Bulletin (TSB) that may be utilized to resolve the P0502.

It is necessary to utilize the scanner’s data stream during testing to maintain the vehicle’s wheel speed. The data stream may be narrowed to only present the most important information, which can help to increase the speed and accuracy of data transmission. If there are discrepancies or faults in the readings from VSS sensors or wheel speed sensors, it may confine the entire system’s malfunctioning area.

After the VSS circuit has been determined to cause the low voltage input, a resistance test on the sensor in question may be conducted on the sensor in question. Testing and replacement instructions for VSS sensors may be found in your vehicle’s information source, which can be located in the owner’s manual.

An oscilloscope should be used to probe the sensor signal and ground wires to get real-time data from each VSS. Lifting or jacking the vehicle is almost usually required to do this kind of test correctly. Start recording the waveform using an oscilloscope as soon as the drive axles are elevated above the ground. Determine whether or not the template has flaws or inconsistencies, and then offer a diagnosis based on your findings.

Routine maintenance is typical for wheel speed sensors, and sensor wire harnesses to be damaged when brakes are repaired. If this error code occurs immediately after a repair, a broken sensor wire harness, connection, or sensor may have been damaged.

A common mistake you must avoid when diagnosing P0502:

Changing the vehicle’s instrument cluster owing to a faulty speedometer is a typical error when this fault code is kept. The vehicle’s speed sensor sends a signal to the instrument cluster, so check there first.

Identifying and fixing the error code P0502

  • Repairing error code P0502 is as simple as doing the steps listed below:
  • Ensuring that the vehicle’s wheels and tires are the appropriate sizes.
  • It’s time to replace the wheel speed sensor or sensors.
  • A hub-bearing replacement.
  • Changing out the instrument panel.
  • In the circuit that measures vehicle speed, the wiring and connections need to be repaired or replaced.
  • New speed sensors may be installed on a vehicle.

Tips for further avoiding P0502 obd2 error:

Wheels with huge diameters are popular with many car owners. However, they have no idea what kind of harm this may do to the car. This may lead to a decrease in ride quality, increased risk of pothole damage, a decrease in braking performance, a decrease in steering precision, and the possibility of error codes like P0502.

Cost of diagnosing the P0502 code: “Vehicle Speed Sensor Low Input” is the diagnostic trouble code (DTC) P0502. This may occur for a variety of reasons, and a technician will need to determine the particular cause of the code in your case. 

If your car’s check engine light comes on, we’ll send one of our licensed mobile technicians to your house or business for an affordable $114.99. A quotation for the proposed remedy and a credit of $20.0 will be issued to you as soon as we have identified the issue. Our 12-month/12,000-mile guarantee covers all of our repairs.

How serious is the P0502 code?

This fault code is not highly significant since it does not affect the vehicle’s ability to drive. Due to the speedometer’s inaccuracy, only a speeding ticket is to be feared when this issue code is shown.