Engine-Codes.com
Engine-Codes – Generic – B0939

B0939 Code - Coolant Level Sensor Circuit High

Quick Answer

The B0939 diagnostic trouble code (DTC) indicates a problem with the coolant level sensor circuit being too high. Common causes include Faulty coolant level sensor, Corroded or damaged wiring in the coolant level sensor circuit, Low coolant level in the cooling system. 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 indicates Coolant Level Sensor Circuit High.
Common causes
Common causes include Faulty coolant level sensor, Corroded or damaged wiring in the coolant level sensor circuit, Low coolant level in the cooling system.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 17, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code B0939 Description

The B0939 diagnostic trouble code (DTC) indicates a problem with the coolant level sensor circuit being too high. The coolant level sensor is responsible for monitoring the level of coolant in the vehicle's cooling system. When the sensor detects that the coolant level is too high, it triggers this code. This issue can have a significant impact on the vehicle's performance and overall health.

OBDII Code B0939 - Coolant Level Sensor Circuit High
B0939 Code - Coolant Level Sensor Circuit High

Common Causes of B0939

  1. Faulty coolant level sensor
  2. Corroded or damaged wiring in the coolant level sensor circuit
  3. Low coolant level in the cooling system
  4. Issues with the engine control module (ECM)
  5. Electrical issues within the vehicle's wiring system

Symptoms of B0939

  1. Engine overheating
  2. Inaccurate coolant level readings on the dashboard
  3. Poor climate control inside the cabin
  4. Check engine light illuminated

How to Fix B0939

  1. Begin by inspecting the coolant level sensor and its wiring for any visible damage or corrosion.
  2. Test the coolant level sensor using a multimeter to check for proper functionality.
  3. If the sensor is faulty, replace it with a new one and ensure it is properly calibrated.
  4. Check the wiring in the coolant level sensor circuit for any damage or loose connections and repair as needed.
  5. Clear the DTC from the vehicle's ECM using a diagnostic scan tool and monitor the coolant level sensor readings to ensure they are accurate.

Cost to Fix B0939

The cost of repairing a coolant level sensor circuit high issue can vary depending on the make and model of the vehicle, as well as the specific cause of the problem. On average, the cost of parts for this repair can range from $50 to $150, while labor costs can range from $100 to $200. Keep in mind that these are rough estimates, and actual costs may vary based on location and other factors. It's recommended to consult with a qualified mechanic for a more accurate cost estimate.

Need more information about the B0939 code?

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

Need Help with the Code?

Get the B0939 code diagnosed by a professional: Find a repair shop in your area

Code B0939 Information for Specific Makes

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 Code

1. What does the OBDII code B0939 mean?

The B0939 code indicates a problem with the coolant level sensor circuit, specifically that the circuit is reading a high voltage, which may reflect a fault in the sensor or wiring.

2. What are the common symptoms of the B0939 code?

Symptoms often include a "low coolant" warning light, inaccurate coolant level readings, engine overheating, or no noticeable symptoms in some cases.

3. What causes the B0939 code to appear?

Common causes include a faulty coolant level sensor, damaged or corroded wiring, a loose connector, or a problem with the vehicle's engine control module (ECM).

4. Can I drive my car with the B0939 code active?

While you may be able to drive your car, ignoring this code could lead to engine overheating if the coolant level is low and unchecked. It’s best to address the issue promptly.

5. How do I diagnose the B0939 code?

Diagnosis involves inspecting the coolant level sensor, checking for damaged wiring or loose connections, and using a multimeter to test for proper voltage in the sensor circuit.

6. How do I fix the B0939 code?

Repairs may include replacing the coolant level sensor, repairing or replacing damaged wiring or connectors, or addressing any issues with the ECM.

7. How much does it cost to fix the B0939 code?

Repair costs can vary but typically range from $100 to $300, depending on whether the sensor, wiring, or other components need replacement.

8. Can a low coolant level cause the B0939 code?

No, a low coolant level itself doesn’t directly cause this code, but it may trigger a "low coolant" warning light if the sensor is functioning properly.

9. What tools are needed to troubleshoot the B0939 code?

You’ll need an OBDII scanner, a multimeter, and basic hand tools to inspect and test the sensor and wiring.

10. Will clearing the B0939 code fix the problem?

Clearing the code with an OBDII scanner will not fix the underlying issue. The problem will likely return unless the root cause is resolved.

Discuss the causes and fixes for B0939 OBDII Code

Submit a New Comment

Code B0939 comments

No comments found for this page.