AutoCodes – GMC – B0940 GMC

B0940 GMC Code - Coolant Level Sensor Circuit Open

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: B0940 GMC indicates Coolant Level Sensor Circuit Open.
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 801

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 B0940 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 B0940 GMC - Coolant Level Sensor Circuit Open - AutoCodes.com — B0940 GMC Code - Coolant Level Sensor Circuit Open

What does this mean?

What are the Possible Causes of the DTC B0940 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 B0940 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 B0940 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 B0940 GMC 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 B0940 GMC Code

1. What are the common symptoms of OBDII code B0940 GMC (Coolant Level Sensor Circuit Open)?

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

2. What can cause the OBDII code B0940 GMC to trigger?

- This code is typically triggered by a malfunction in the coolant level sensor circuit, such as a broken wire, loose connection, or a faulty sensor.

3. How can I diagnose the cause of the Coolant Level Sensor Circuit Open code?

- To diagnose the issue, you can visually inspect the coolant level sensor and its wiring for any visible damage. Using a multimeter, you can also check for continuity and proper voltage in the circuit.

4. Can a low coolant level trigger the B0940 code?

- Yes, a low coolant level can potentially trigger the B0940 code as the sensor may not be able to accurately detect the coolant level when it is below the normal range.

5. What are the repair options for fixing the Coolant Level Sensor Circuit Open issue?

- Repair options include repairing or replacing damaged wiring, ensuring proper sensor connection, or replacing the coolant level sensor itself if it is found to be faulty.

6. Is it safe to drive with the B0940 OBDII code present?

- It is generally safe to drive with the B0940 code, but it is recommended to address the issue promptly to prevent potential overheating problems or engine damage due to inaccurate coolant level readings.

7. Can a DIYer fix the Coolant Level Sensor Circuit Open problem?

- Depending on your level of automotive repair experience, DIYers may be able to address this issue by following diagnostic procedures, checking the sensor and wiring, and making necessary repairs or replacements.

8. How much does it cost to repair the Coolant Level Sensor Circuit Open issue?

- The cost of repairing the B0940 code can vary depending on the underlying cause. Simple fixes like repairing a wire may be inexpensive, while replacing a faulty sensor can cost more.

9. Will resetting the OBDII code make the issue go away permanently?

- Resetting the code may temporarily clear the check engine light, but if the underlying issue causing the B0940 code is not fixed, the code is likely to reappear.

10. Can the Coolant Level Sensor Circuit Open code be related to other cooling system problems?

- While the B0940 code specifically relates to the coolant level sensor circuit, it is possible for issues with the cooling system, such as a leak or a malfunctioning thermostat, to indirectly affect the sensor's operation.