AutoCodes – Cadillac – B0178 Cadillac

B0178 Cadillac Code - Output Air Temperature Sensor 2 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 2, Output Air Temperature Sensor 2 harness is open or shorted, Output Air Temperature Sensor 2 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: B0178 Cadillac indicates Output Air Temperature Sensor 2 Circuit.
Common causes: Common causes include Faulty Output Air Temperature Sensor 2, Output Air Temperature Sensor 2 harness is open or shorted, Output Air Temperature Sensor 2 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.

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Code Popularity 996

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 10, 2021

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code B0178 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 B0178 Cadillac - Output Air Temperature Sensor 2 Circuit - AutoCodes.com — B0178 Cadillac Code - Output Air Temperature Sensor 2 Circuit

What does this mean?

What are the Possible Causes of the DTC B0178 Cadillac?

Faulty Output Air Temperature Sensor 2
Output Air Temperature Sensor 2 harness is open or shorted
Output Air Temperature Sensor 2 circuit poor electrical connection
Faulty Heating, Ventilation, and Air Conditioning (HVAC) Control Module

How to Fix the DTC B0178 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

B0178 05: Output Air Temperature Sensor 2 Circuit Short to Battery or Open
B0178 02: Output Air Temperature Sensor 2 Circuit Short to Ground

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B0178 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.

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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 B0178 Cadillac Code

1. What are the common symptoms of OBDII code B0178 related to the Output Air Temperature Sensor 2 Circuit in a Cadillac?

- Common symptoms include issues with the heating and air conditioning system, incorrect temperature readings, and potential fluctuations in interior cabin temperature.

2. What are some possible causes of OBDII code B0178 in a Cadillac, specifically related to the Output Air Temperature Sensor 2 Circuit?

- Potential causes may include a faulty output air temperature sensor, wiring issues, electrical problems, or a malfunctioning HVAC control module.

3. How can I diagnose the OBDII code B0178 in a Cadillac related to the Output Air Temperature Sensor 2 Circuit?

- Diagnosis typically involves using a scan tool to retrieve the specific trouble code, testing the output air temperature sensor and related wiring, and checking for any loose connections or damaged components.

4. Are there any repair tips for fixing OBDII code B0178 in a Cadillac due to issues with the Output Air Temperature Sensor 2 Circuit?

- Repair tips may include checking and repairing any damaged wiring, replacing the faulty output air temperature sensor, ensuring proper connections, and resetting the trouble code after repairs.

5. Can I drive my Cadillac with OBDII code B0178 related to the Output Air Temperature Sensor 2 Circuit?

- It is generally safe to drive the vehicle with this code, but it is recommended to address the issue promptly to avoid potential discomfort with the heating and cooling systems.

6. Is it possible to reset the OBDII code B0178 in a Cadillac without fixing the underlying issue related to the Output Air Temperature Sensor 2 Circuit?

- While you can clear the code with a scan tool, it is crucial to address the root cause of the problem to prevent recurring issues and ensure proper functionality of the HVAC system.

7. How much does it typically cost to repair OBDII code B0178 in a Cadillac caused by problems with the Output Air Temperature Sensor 2 Circuit?

- Repair costs can vary depending on the specific issue, but they may range from $100 to $300 for sensor replacement or wiring repairs at a dealership or automotive repair shop.

8. Are there any preventive measures to avoid encountering OBDII code B0178 related to the Output Air Temperature Sensor 2 Circuit in a Cadillac?

- Regular maintenance checks, inspecting the HVAC system components, and addressing any temperature-related issues promptly can help prevent this trouble code from appearing.

9. Can a DIY enthusiast with basic automotive knowledge fix OBDII code B0178 in a Cadillac related to the Output Air Temperature Sensor 2 Circuit?

- Depending on the exact cause of the issue, a DIY enthusiast may be able to replace the sensor or repair wiring themselves, but it is recommended to have a professional diagnosis if unsure.

10. How long does it typically take to repair OBDII code B0178 in a Cadillac due to problems with the Output Air Temperature Sensor 2 Circuit?

- The repair time can vary based on the specific problem and the expertise of the technician, but it may take anywhere from 1 to 3 hours to diagnose and fix the issue.