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Engine-Codes – BMW – P0977 BMW

P0977 BMW Code - Shift Solenoid 'B' Control Circuit High

Quick Answer

The P0977 code for BMW indicates a problem with the Shift Solenoid 'B' Control Circuit being too high. Common causes include Faulty shift solenoid: The shift solenoid 'B' may be defective, causing it to send incorrect signals to the transmission, Wiring issues: Damage or corrosion in the wiring harness connected to the shift solenoid can disrupt the electrical signals, Transmission fluid contamination: Contaminated or degraded transmission fluid can affect the solenoid's performance. 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
P0977 BMW indicates Shift Solenoid 'B' Control Circuit High.
Common causes
Common causes include Faulty shift solenoid: The shift solenoid 'B' may be defective, causing it to send incorrect signals to the transmission, Wiring issues: Damage or corrosion in the wiring harness connected to the shift solenoid can disrupt the electrical signals, Transmission fluid contamination: Contaminated or degraded transmission fluid can affect the solenoid's performance.
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 11, 2024
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Code P0977 BMW Description

The P0977 code for BMW indicates a problem with the Shift Solenoid 'B' Control Circuit being too high. The shift solenoid is a crucial component of the transmission system, responsible for regulating the flow of transmission fluid to control gear shifting. In this case, a high voltage condition is detected in the circuit that controls the operation of Shift Solenoid 'B'. This issue can lead to improper gear shifting, transmission slippage, harsh shifting, or even the vehicle not shifting at all. If left unaddressed, it can cause further damage to the transmission system, leading to costly repairs.

OBDII Code P0977 BMW - Shift Solenoid 'B' Control Circuit High
P0977 BMW Code - Shift Solenoid 'B' Control Circuit High

Common Causes of P0977 BMW

  1. Faulty shift solenoid: The shift solenoid 'B' may be defective, causing it to send incorrect signals to the transmission.
  2. Wiring issues: Damage or corrosion in the wiring harness connected to the shift solenoid can disrupt the electrical signals.
  3. Transmission fluid contamination: Contaminated or degraded transmission fluid can affect the solenoid's performance.
  4. Transmission control module (TCM) failure: A malfunctioning TCM can lead to communication issues with the shift solenoid.
  5. Poor electrical connection: Loose or poor connections in the circuit can cause high voltage readings and trigger the code.

Symptoms of P0977 BMW

  1. Harsh or delayed shifting: The vehicle may experience abrupt or delayed gear shifts, making driving uncomfortable.
  2. Transmission slippage: The transmission may slip out of gear unexpectedly, causing a loss of power and acceleration.
  3. Transmission not shifting: The vehicle may get stuck in a particular gear and not shift up or down as needed.
  4. Illuminated Check Engine Light: The vehicle's onboard diagnostic system may trigger the Check Engine Light to indicate a problem with the transmission system.

How to Fix P0977 BMW

  1. Diagnostic scan: Use an OBD-II scanner to retrieve the trouble code and pinpoint the exact cause of the issue.
  2. Inspect wiring and connections: Check the wiring harness and connections for any damage, corrosion, or loose connections. Repair or replace as necessary.
  3. Test shift solenoid 'B': Test the shift solenoid 'B' to determine if it is functioning properly. Replace if found faulty.
  4. Check transmission fluid: Inspect the transmission fluid for contamination or low levels. Perform a fluid flush and refill if needed.
  5. Resetting the code: After completing the repairs, clear the code and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0977 BMW

The cost of repairing a Shift Solenoid 'B' Control Circuit High issue can vary depending on the extent of the damage and the specific components that need to be replaced. On average, the cost of parts for a shift solenoid replacement can range from $100 to $300, while labor costs can vary between $100 to $300. Therefore, the total repair cost can range from $200 to $600. Keep in mind that additional costs may apply if other components need to be replaced or if further diagnostics are required. It is recommended to consult a professional mechanic for a more accurate cost estimate based on your vehicle's make and model.

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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 P0977 BMW Code

1. What does the OBDII code P0977 mean on a BMW?

P0977 indicates a high electrical condition in the Shift Solenoid 'B' Control Circuit, which can affect the transmission's ability to shift gears properly.

2. What are the common symptoms of a P0977 code on a BMW?

Symptoms may include harsh or delayed shifting, failure to shift gears, transmission stuck in one gear, or the illumination of the check engine light.

3. What causes the P0977 code to appear on a BMW?

Common causes include a faulty shift solenoid 'B', damaged wiring or connectors in the circuit, transmission fluid contamination, or a malfunctioning transmission control module (TCM).

4. Can I drive my BMW with a P0977 code?

Driving with this code is not recommended, as it may lead to further transmission damage or unsafe driving conditions due to gear-shifting issues.

5. How do I diagnose the P0977 code on a BMW?

Diagnosis involves inspecting the wiring and connectors for damage, testing the shift solenoid 'B' for proper operation, and checking the transmission fluid for contamination or low levels.

6. How do I fix a P0977 code on my BMW?

Repairs may include replacing the shift solenoid 'B', repairing damaged wiring or connectors, flushing and replacing the transmission fluid, or reprogramming the TCM if necessary.

7. How much does it cost to fix the P0977 code on a BMW?

Repair costs can vary widely, ranging from $100 to $400 for solenoid replacement, and higher if additional components like the TCM or wiring harness need repairs.

8. Can dirty transmission fluid cause the P0977 code?

Yes, contaminated or degraded transmission fluid can cause solenoid malfunctions, triggering the P0977 code. A fluid flush may resolve the issue in some cases.

9. Do I need to replace the transmission to fix the P0977 code on a BMW?

In most cases, replacing the transmission is not necessary. The issue is typically resolved by repairing or replacing the faulty solenoid or addressing wiring issues.

10. Will clearing the P0977 code fix the problem?

Clearing the code will remove it temporarily, but the underlying issue must be resolved to prevent the code from returning.

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