AutoCodes – GMC – B0939 GMC

B0939 GMC Code - Coolant Level Sensor Circuit High

Quick Answer

The Powertrain Control Module (PCM) monitors the Coolant Level Sensor. Common causes include Low Coolant Level, Faulty Coolant Level Sensor, Coolant Level Sensor harness is open or shorted. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: B0939 GMC indicates Coolant Level Sensor Circuit High.
Common causes: Common causes include Low Coolant Level, Faulty Coolant Level Sensor, Coolant Level Sensor harness is open or shorted.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 842

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

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

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B0939 GMC Description

The Powertrain Control Module (PCM) monitors the Coolant Level Sensor. The PCM sets the OBDII code when the Coolant Level Sensor is not to factory specifications.

OBDII Code B0939 GMC - Coolant Level Sensor Circuit High - AutoCodes.com — B0939 GMC Code - Coolant Level Sensor Circuit High

What does this mean?

What are the Possible Causes of the DTC B0939 GMC?

Low Coolant Level
Faulty Coolant Level Sensor
Coolant Level Sensor harness is open or shorted
Coolant Level Sensor circuit poor electrical connection

How to Fix the DTC B0939 GMC?

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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B0939 GMC 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 B0939 GMC code?

Need more information on how to fix the B0939 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

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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 B0939 GMC Code

1. What are the common symptoms of OBDII code B0939 GMC (Coolant Level Sensor Circuit High)?

- Common symptoms include an illuminated check engine light, inaccurate coolant level readings on the dashboard, and potential overheating issues.

2. What could cause the OBDII code B0939 GMC to trigger?

- The code may be triggered due to a faulty coolant level sensor, wiring issues, a corroded connector, or a problem with the coolant level sensor circuit.

3. How can I diagnose the Coolant Level Sensor Circuit High issue?

- Diagnosing the issue involves checking the coolant level sensor and its wiring for any visible damage, testing the sensor's resistance, and ensuring proper connections.

4. Can I continue driving with the OBDII code B0939 GMC active?

- It is not recommended to drive with the code active, as inaccurate coolant level readings can lead to potential engine overheating and other serious issues.

5. What is the repair process for resolving the Coolant Level Sensor Circuit High problem?

- The repair process typically involves replacing the faulty coolant level sensor, repairing any damaged wiring or connectors, and clearing the OBDII code.

6. Are there any DIY tips for fixing the Coolant Level Sensor Circuit High issue?

- DIY tips include checking and cleaning the sensor connections, inspecting the wiring for damage, and replacing the coolant level sensor if necessary.

7. Will resetting the OBDII code B0939 GMC solve the problem temporarily?

- Resetting the code may temporarily turn off the check engine light, but it will not fix the underlying issue causing the Coolant Level Sensor Circuit High fault.

8. How critical is it to address the OBDII code B0939 GMC promptly?

- It is important to address the code promptly to avoid potential engine damage from overheating due to inaccurate coolant level readings.

9. Can a professional mechanic help diagnose and repair the Coolant Level Sensor Circuit High problem?

- Yes, a qualified mechanic can accurately diagnose the issue using specialized tools and repair the problem by replacing the faulty components.

10. Is the OBDII code B0939 GMC specific to certain GMC vehicle models?

- Yes, the code B0939 related to the Coolant Level Sensor Circuit High is specific to GMC vehicles and may vary in its application across different models.