Shop Parts keyboard_double_arrow_right
Need car parts? Select your vehicle
Reading Time: 4 minutes
Summary
  • The P0502 stands for “Vehicle Speed Sensor A Low Input.” It’s logged when the PCM detects a low input voltage signal from VSS A.
  • Some problems that could trigger the code include a faulty VSS, metal debris buildup on the speed sensor, and wiring harness issues.
  • Some symptoms to look out for include an erratic speedometer, illuminated warning lights, and irregular transmission shift patterns.

A P0502 code set by your vehicle’s powertrain control module indicates a possible issue with your vehicle speed sensor (VSS) or its circuit. This device monitors your vehicle speed so that the PCM can properly adjust functions, such as torque converter clutch lock up and shift scheduling.

The code P0502 is set once your PCM detects a low voltage signal from your VSS A. This usually refers to the primary sensor in vehicles that have more than one device installed. Read on to learn more about this trouble code.

What Does the P0502 Code Mean?

Diagnostic trouble code (DTC) P0502 stands for “Vehicle Speed Sensor A Low Input.” This code is applicable to select models from 1996 onwards.

See also  P0720 Code: Output Speed Sensor Circuit Malfunction

Your vehicle makes use of a speed sensor to monitor rotational speed to estimate how fast the vehicle is going.  Most of these sensors are electromagnetic. They’re paired with a toothed reluctor ring wheel or gear that’s typically attached to the transmission/transfer case output shaft or differential gear.

vehicle speed sensor replacement isolated
Once the PCM detects a low input voltage signal from VSS A, it can trigger the P0502 code.

The sensor sends data to the PCM using voltage signals. Once the PCM detects a low input voltage signal from VSS A, it can trigger the P0502 code. This issue can be electrical or mechanical in nature.

Note: The definition of code P0502 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What Are the Common Causes of the P0502 Code?

  • Faulty VSS
  • Metal debris build up on the speed sensor
  • Wiring harness or connector issues
  • Worn out reluctor ring teeth
  • An issue with one of the vehicle’s control modules

What Are the Common Symptoms of the P0502 Code?

  • Erratic speedometer/odometer operation
  • Illuminated warning lights (check engine light, anti-lock brake light, etc.)
  • Irregular transmission shift pattern
  • Inoperative vehicles systems (anti-lock brake, traction control, etc.)

How to Diagnose the P0502 Code

DTC P0502 is a generic code that can be logged across several makes and models. However, this does not mean that there’s only one way to diagnose its underlying cause. The steps for troubleshooting this code will vary depending on the specific vehicle that you own.

See also  What Is a Speed Sensor and What Does It Do?

You can check out these videos if you plan to work on your vehicle yourself:

How to Fix the P0502 Code

Symptoms and triggers of code P0502 may be similar across various vehicles. But that does not mean that the steps to get this issue fixed are the same for all. All vehicles are built differently. Make sure to check vehicle-specific repair procedures before doing anything with your vehicle. 
We recommend consulting the vehicle repair manual or an online repair database to learn the appropriate diagnostic and repair procedures for this code. If you’re not an experienced DIYer, we strongly advise leaving the job to a trusted mechanic.

Parts to Fix a Triggered P0502 Code

The vehicle speed sensor is an important component in your vehicle. It may lead to the PCM setting the P0502 code when it detects faults with the VSS. The VSS plays a critical role in your vehicle’s transmission and anti-lock braking system. Need to get a replacement speed sensor online? Look no further, as CarParts.com is your one-stop shop for all your vehicle’s needs.

CarParts.com offers replacement sensors with excellent performance and good value. Our parts and accessories are sourced from only the best manufacturers in the industry. Shopping for the right sensor is easy since you only need to indicate your vehicle’s year, make, and model to see a list of compatible parts.

See also  Fluid Leaks 101: Find Out What’s Leaking From Your Car

Get a new speed sensor here at CarParts.com and get your vehicle back on the road as soon as possible.

Shop this Project

Replacement – Front or Rear, Driver Side ABS Speed Sensor – Sold individually
, P0502 Code: Vehicle Speed Sensor A Low Input
$18.99 Price and rating may change from the time content is published.
Crown® – 640131 Speedometer – Direct Fit, Assembly
, P0502 Code: Vehicle Speed Sensor A Low Input
$79.49 Price and rating may change from the time content is published.
Dorman® – 917-554 OE Solutions Series ABS Reluctor Ring Sold individually
, P0502 Code: Vehicle Speed Sensor A Low Input
$56.99 Price and rating may change from the time content is published.
AC Delco® – 24262815 Torque Converter – Direct Fit, Sold individually
, P0502 Code: Vehicle Speed Sensor A Low Input
$424.49 Price and rating may change from the time content is published.

About The Author
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

P4 Holiday 2024
Subscribe
Notify of
guest
0 Comments
Inline Feedbacks
View all comments
expand_more
CarParts.com Answers BE PART OF OUR COMMUNITY: Share your knowledge & help fellow drivers Join Now
The owner of this website has made a commitment to accessibility and inclusion, please report any problems that you encounter using the contact form on this website. This site uses the WP ADA Compliance Check plugin to enhance accessibility.