AutoCodes – Cadillac – B0509 Cadillac

B0509 Cadillac Code - Output Air Temperature Sensor 3 Circuit

Quick Answer

Air temperature sensors allow the Heating, Ventilation, and Air Conditioning (HVAC) Control Module to monitor the temperature of the discharge air in the HVAC ducts. Common causes include Faulty Output Air Temperature Sensor 3, Output Air Temperature Sensor 3 harness is open or shorted, Output Air Temperature Sensor 3 circuit poor electrical connection. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: B0509 Cadillac indicates Output Air Temperature Sensor 3 Circuit.
Common causes: Common causes include Faulty Output Air Temperature Sensor 3, Output Air Temperature Sensor 3 harness is open or shorted, Output Air Temperature Sensor 3 circuit poor electrical connection.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 876

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 11, 2021

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code B0509 Cadillac Description

Air temperature sensors allow the Heating, Ventilation, and Air Conditioning (HVAC) Control Module to monitor the temperature of the discharge air in the HVAC ducts. The module applies 5 volts to internal input resistors that are connected to the signal circuits of the air temperature sensors. The module provides ground to the air temperature sensors through the low reference circuit. The HVAC control module monitors the voltage drops across the air temperature sensors and uses the inputs for automatic control calculations. When the duct air temperatures are cold, the resistances of the sensors are high and the voltage signals are high. When the duct air temperatures are hot, the resistances of the sensors are low and the voltage signals are low. The HVAC control module converts the voltage values to count values where 1 volt is approximately equal to 51 counts.

OBDII Code B0509 Cadillac - Output Air Temperature Sensor 3 Circuit - AutoCodes.com — B0509 Cadillac Code - Output Air Temperature Sensor 3 Circuit

What does this mean?

What are the Possible Causes of the DTC B0509 Cadillac?

Faulty Output Air Temperature Sensor 3
Output Air Temperature Sensor 3 harness is open or shorted
Output Air Temperature Sensor 3 circuit poor electrical connection
Faulty Heating, Ventilation, and Air Conditioning (HVAC) Control Module

How to Fix the DTC B0509 Cadillac?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

B0509 05: Output Air Temperature Sensor 3 Circuit Short to Battery or Open
B0509 02: Output Air Temperature Sensor 3 Circuit Short to Ground

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B0509 Cadillac code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the B0509 Cadillac code?

Need more information on how to fix the B0509 Cadillac code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B0509 Cadillac code diagnosed by a professional: Find a repair shop in your area

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about B0509 Cadillac Code

1. What are the common symptoms of an OBDII code B0509 related to the Output Air Temperature Sensor 3 Circuit in a Cadillac?

- Common symptoms include issues with the HVAC system, such as inconsistent air temperature control or incorrect readings on the climate control display.

2. What can cause the OBDII code B0509 indicating a problem with the Output Air Temperature Sensor 3 Circuit in a Cadillac?

- Possible causes include a faulty output air temperature sensor, damaged wiring or connectors in the circuit, or issues with the HVAC control module.

3. How can I diagnose the OBDII code B0509 in my Cadillac related to the Output Air Temperature Sensor 3 Circuit?

- Diagnosis typically involves using an OBDII scanner to read the code, checking the wiring and connectors for any visible damage, and testing the output air temperature sensor for proper functionality.

4. Are there any simple repairs I can attempt to fix the OBDII code B0509 Output Air Temperature Sensor 3 Circuit issue in my Cadillac?

- You may try checking and repairing any damaged wiring or connectors in the circuit, and replacing the output air temperature sensor if it is found to be faulty.

5. Can a DIY enthusiast easily fix the OBDII code B0509 related to the Output Air Temperature Sensor 3 Circuit in a Cadillac?

- While some basic repairs like checking and replacing damaged wiring or connectors can be attempted by a DIY enthusiast, complex diagnostic procedures and sensor replacements may require professional assistance.

6. How important is it to address the OBDII code B0509 indicating a problem with the Output Air Temperature Sensor 3 Circuit in a Cadillac?

- Ignoring this code may lead to issues with the proper functioning of the HVAC system in your Cadillac, affecting your comfort and potentially causing further damage if left unresolved.

7. Is it safe to continue driving my Cadillac with the OBDII code B0509 related to the Output Air Temperature Sensor 3 Circuit?

- It is generally not recommended to drive your Cadillac with unresolved OBDII codes, as they can indicate underlying issues that may impact the vehicle's performance and safety.

8. How much does it typically cost to repair the OBDII code B0509 Output Air Temperature Sensor 3 Circuit problem in a Cadillac?

- The cost of repair can vary depending on the exact cause of the issue, but it may involve expenses for parts replacement, labor charges, and potential diagnostic fees.

9. Can extreme weather conditions affect the likelihood of triggering the OBDII code B0509 in a Cadillac?

- Extreme temperatures or environmental conditions can potentially impact the performance of sensors and circuits related to the HVAC system, increasing the chances of triggering this particular OBDII code.

10. Are there any preventive maintenance measures that can help prevent the recurrence of the OBDII code B0509 Output Air Temperature Sensor 3 Circuit problem in a Cadillac?

- Regular inspection of the HVAC system, including checking for loose connections and damaged wiring, can help identify potential issues early and prevent the reoccurrence of this OBDII code.