B0939 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 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.
Code B0939 Description
What are the Possible Causes of the DTC B0939?
- 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?
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 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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Information for Specific Makes
- B0939 Buick — Coolant Level Sensor Circuit High
- B0939 Cadillac — Coolant Level Sensor Circuit High
- B0939 Chevrolet — Coolant Level Sensor Circuit High
- B0939 GMC — Coolant Level Sensor Circuit High
- B0939 Pontiac — Coolant Level Sensor Circuit High
- B0939 Saturn — Coolant Level Sensor Circuit High
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
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