OBD Guide

B0939

Coolant Level Sensor Circuit High

B0939 is an OBD-II diagnostic trouble code meaning: Coolant Level Sensor Circuit High. Common causes: coolant level sensor malfunction, short circuit in wiring harness. Estimated repair cost: $22–56.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$22–56 (est.)

Symptoms

  • False coolant level readings on the dashboard
  • Check engine light is on
  • The engine may go into emergency mode
  • Incorrect operation of the cooling system

Causes

  • Coolant level sensor malfunction
  • Short circuit in wiring harness
  • Broken or damaged wires
  • Problems with the ECU
  • Corrosion of sensor contacts or connectors

How to Fix

  1. Check the coolant level and add if necessary
  2. Inspect the coolant level sensor for damage
  3. Check the wiring harness and connectors for damage or corrosion.
  4. Test the sensor with a multimeter
  5. Replace the sensor if a fault is detected
  6. Clean or replace connectors if necessary
  7. Check the ECU for errors

Related codes

Error B0939 by Vehicle Brand

FAQ

What does the B0939 code mean?

B0939 is an OBD-II diagnostic trouble code that indicates: Coolant Level Sensor Circuit High

What causes a B0939 error code?

The most common causes of B0939 include: Coolant level sensor malfunction; Short circuit in wiring harness; Broken or damaged wires; Problems with the ECU.

How do I fix a B0939 diagnostic trouble code?

To fix B0939: Check the coolant level and add if necessary. Inspect the coolant level sensor for damage. Check the wiring harness and connectors for damage or corrosion.. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B0939?

Limited driving only, diagnose soon

How much does it cost to fix B0939?

The estimated repair cost for B0939 is $22–56. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat