B0871 - Transmission Control Module (TCM) Fault in Common Vehicles like 2016-2021 Chevrolet Malibu and 2017-2021 GMC Acadia

Quick Answer

B0871 means: B0871 indicates a fault in the transmission control module, affecting vehicle shifting and performance.

Fix: Check and replace faulty components Cost: $800 - $1,500 Time: 90-180 minutes

Can I drive with B0871? Address immediately to prevent further transmission damage.

Common Questions

What does B0871 mean and how does it affect my car?

The B0871 code refers to a fault in the transmission control module (TCM), which is responsible for managing your vehicle's shifts. If there's an issue with the TCM, you might notice problems like difficulty shifting gears, erratic performance, or even the vehicle going into limp mode. Over time, ignoring this code can lead to more severe transmission issues and costly repairs.

What are the most common causes of B0871 and how much does it cost to fix?

The most common causes of the B0871 code include a faulty transmission control module, which can cost between $800 and $1,500 to replace. Other causes include damaged wiring, which could cost $150 to $400 to repair, and occasionally, software glitches that might only need a software update costing $50 to $150.

Can I drive my car with B0871 or should I stop immediately?

It’s best to avoid driving your vehicle if the B0871 code is present, as it may lead to limited power and further transmission damage. If you must drive, do so cautiously and avoid high speeds or heavy acceleration. Schedule a diagnostic as soon as possible.

How can I diagnose B0871 myself using GeekOBD APP?

To diagnose B0871 using the GeekOBD APP, start by connecting the device to your vehicle's OBD2 port. Run a scan to retrieve the fault codes, focusing on any related to the transmission. Review freeze frame data for context and check for any other simultaneous codes that may provide further insight into the issue.

What vehicles are most commonly affected by B0871?

The B0871 code is frequently reported in vehicles like the 2016-2021 Chevrolet Malibu and the 2017-2021 GMC Acadia, along with other GM models. It's essential to keep an eye on recalls or technical service bulletins (TSBs) related to the TCM for your specific vehicle.

How can I prevent B0871 from happening again?

To prevent the B0871 code from recurring, ensure regular maintenance of your vehicle’s transmission system. This includes checking and changing the transmission fluid at recommended intervals, inspecting wiring and connectors for wear, and keeping an eye on any software updates from the manufacturer.

What is B0871?

The diagnostic trouble code (DTC) B0871 indicates a fault related to the transmission control module (TCM) in your vehicle. This code typically points to an issue with the TCM’s ability to communicate effectively with other modules in the vehicle, such as the engine control module (ECM) and the body control module (BCM). When this code appears, it suggests that the TCM is either malfunctioning or has encountered an error in its operation. For car owners, this can lead to various performance issues, including erratic shifting, inability to shift gears, or the vehicle going into limp mode, where the power is restricted to prevent further damage. Commonly found in models like the 2016-2021 Chevrolet Malibu and the 2017-2021 GMC Acadia, drivers may first notice the check engine light illuminating on the dashboard. As the TCM plays a crucial role in the vehicle’s transmission system, resolving this issue promptly is essential to avoid further complications and costly repairs. Ignoring this code can lead to more severe transmission problems down the line, resulting in extensive repairs and higher costs. If you see the B0871 code, it’s advisable to consult a qualified technician who can perform the necessary diagnostics and repairs.

System: B - Body (Airbags, Lighting, Security, Climate Control)

Symptoms

Common symptoms when B0871 is present:

  • The check engine light may stay on constantly, indicating a critical issue with the TCM.
  • You might experience erratic shifting, where the vehicle shifts gears unexpectedly or struggles to shift at all.
  • Fuel economy may decrease significantly, with some drivers reporting up to a 15% drop in efficiency due to improper gear engagement.
  • The vehicle may enter limp mode, where power is limited, making it difficult to accelerate or maintain speed.
  • In some cases, unusual noises from the transmission may be heard, indicating potential internal issues.

Possible Causes

Most common causes of B0871 (ordered by frequency):

  1. The most common cause of the B0871 code is a faulty transmission control module, which can occur in about 60% of cases. This may result from electrical issues or internal failures within the TCM.
  2. Another common cause is damaged wiring or connectors associated with the TCM, which can lead to communication failures between modules, accounting for around 25% of cases.
  3. A third cause could be low transmission fluid levels or dirty fluid, which can affect the TCM’s performance. Regular maintenance can prevent this issue.
  4. Less commonly, external factors such as water intrusion into the TCM housing can cause faults, especially in older vehicles.
  5. In rare cases, a software glitch within the TCM can trigger the B0871 code, often resolved with a simple software update.

B0871 Repair Costs

Cost Breakdown by Repair Type

Transmission Control Module Replacement

Replacing the faulty TCM with a new or refurbished unit.

  • Total: $800 - $1,500
  • Success rate: 90%
Wiring Repair

Repairing or replacing damaged wiring or connectors linked to the TCM.

  • Total: $150 - $400
  • Success rate: 85%
Software Update

Performing a software update to fix potential glitches in the TCM.

  • Total: $50 - $150
  • Success rate: 75%
Money-Saving Tips for B0871
  • Start with the most common and least expensive repairs first
  • Use GeekOBD APP to confirm diagnosis before replacing expensive parts
  • Consider preventive maintenance to avoid future occurrences
  • Compare prices for OEM vs aftermarket parts based on your needs
  • Address the issue promptly to prevent more expensive secondary damage

Diagnostic Steps

Professional B0871 Diagnosis Process

Follow these systematic steps to accurately diagnose B0871. Each step builds on the previous one to ensure accurate diagnosis.

Step 1: Step 1: Perform an initial visual inspection to check for any damaged wiring, loose connections, or signs of corrosion that may affect the TCM (5-10 minutes)

Step 1: Perform an initial visual inspection to check for any damaged wiring, loose connections, or signs of corrosion that may affect the TCM (5-10 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 2: Step 2: Use the GeekOBD APP to perform an OBD2 scan and retrieve all fault codes along with freeze frame data to understand the vehicle's condition at the time of the fault (10-15 minutes)

Step 2: Use the GeekOBD APP to perform an OBD2 scan and retrieve all fault codes along with freeze frame data to understand the vehicle's condition at the time of the fault (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 3: Step 3: Conduct component testing using a multimeter or dedicated diagnostic tools to assess the TCM and related wiring (20-30 minutes)

Step 3: Conduct component testing using a multimeter or dedicated diagnostic tools to assess the TCM and related wiring (20-30 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 4: Step 4: After repairs, perform a system function test to ensure proper operation and clear any stored codes (10-15 minutes)

Step 4: After repairs, perform a system function test to ensure proper operation and clear any stored codes (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 5: Step 5: Conduct a road test under various conditions to confirm that the issue is resolved and the vehicle operates normally (15-20 minutes)

Step 5: Conduct a road test under various conditions to confirm that the issue is resolved and the vehicle operates normally (15-20 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.

Important Notes

  • Always verify the repair with GeekOBD APP after completing diagnostic steps
  • Clear codes and test drive to ensure the problem is resolved
  • Address underlying causes to prevent code recurrence

Real Repair Case Studies

Case Study 1: Transmission Control Module Replacement in a 2018 Chevrolet Malibu

Vehicle: 2018 Chevrolet Malibu, 45,000 miles

Problem: Customer reported the check engine light was on, and the vehicle was experiencing rough shifting.

Diagnosis: After running diagnostics with the GeekOBD APP, the B0871 code was confirmed. A visual inspection revealed corroded connectors leading to the TCM.

Solution: Replaced the TCM and repaired the damaged wiring. Updated the vehicle's software.

Cost: $1,200 (parts: TCM - $900, wiring repair - $200, labor - $100)

Result: Post-repair, the vehicle shifted smoothly, and the check engine light was cleared.

Case Study 2: Wiring Repair for a 2019 GMC Acadia

Vehicle: 2019 GMC Acadia, 30,000 miles

Problem: Owner complained of erratic shifting and a check engine light.

Diagnosis: The GeekOBD APP scan revealed B0871 and additional codes related to the TCM. Inspection showed damaged wiring harness.

Solution: Repaired wiring connections and cleared codes. No component replacement was necessary.

Cost: $300 (parts: wiring harness repair - $200, labor - $100)

Result: After the repair, the vehicle's performance improved significantly, with no further issues reported.

Diagnose B0871

Use GeekOBD APP for professional diagnosis!

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  • Advanced diagnostic features
  • Step-by-step repair guidance
  • Professional-grade analysis
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Code Information

Code: B0871
System: Body (Airbags, Lighting, Security, Climate Control)
Severity: HIGH
Category: Body Codes