What is OBD-II Code P2643 – Torque Management Feedback Signal B Low

What is OBD-II Code P2643 – Torque Management Feedback Signal B Low

Modern cars are equipped with onboard diagnostic systems (OBD) that monitor and control various functions of the vehicle. These systems use sensors and computers to detect and diagnose problems that can affect the performance, fuel efficiency, and emissions of the car. If a problem is detected, the OBD system generates a code that can be read using a scan tool. One of these codes is P2643, which relates to the torque management feedback signal B low. In this article, we will explain what this code means and how to repair the issue.

What is OBD-II Code P2643?

P2643 is an OBD-II code that is related to the torque management feedback signal B low. This code is set when the PCM (powertrain control module) detects that the signal from the feedback circuit to the PCM is lower than the expected value. The PCM uses this feedback signal to control the torque converter clutch (TCC) engagement and disengagement. The TCC is a critical component of the automatic transmission system, and it is responsible for transmitting engine power to the wheels in a direct manner.

When the PCM detects that the feedback signal is low, it will typically illuminate the check engine light on the dashboard. The vehicle may also experience drivability issues, such as harsh shifting, poor acceleration, or stalling. It is essential to diagnose and repair this issue as soon as possible to avoid more severe problems and higher costs.

How to diagnose OBD-II Code P2643?

Diagnosing the P2643 code requires following a few steps to isolate the issue correctly. Here are some of the steps that a mechanic would typically take:

Step 1: Use a scan tool to read and record the codes. This will give you an error code P2643, as well as other related codes if present.

Step 2: Check the transmission fluid level and condition. Low or dirty fluid can cause issues with the TCC.

Step 3: Use a multimeter to check the continuity and resistance of the feedback circuit and the TCC solenoid circuit. A broken or shorted wire can cause the low signal.

Step 4: Check the TCC solenoid valve for proper operation. A faulty solenoid can cause the TCC not to engage properly, resulting in a low feedback signal.

Step 5: Inspect the PCM for any signs of water, corrosion, or damage to the circuit boards and connectors.

How to repair OBD-II Code P2643?

Once you have diagnosed the issue and identified the root cause of the low feedback signal, you can take steps to repair it. Here are some of the most common repair solutions:

Solution 1: Replace the TCC solenoid valve. If the solenoid is faulty or defective, replacing it can solve the issue.

Solution 2: Repair or replace any damaged wires or connectors in the feedback circuit. This can be a tedious process, but it is essential to ensure that the signal is transmitting correctly.

Solution 3: Check the PCM for any damage or malfunction. If the PCM is faulty, it may need to be replaced or repaired by a professional.

Solution 4: Perform a software update or reflash. In some cases, a software glitch in the PCM can cause the low feedback signal issue. A professional mechanic can update or reflash the software to fix the issue.


1. What happens if I ignore the P2643 code?

Ignoring the P2643 code can lead to more severe issues with the transmission, such as slipping, overheating, or failure. These issues can be costly to repair and can even cause accidents if the vehicle loses power or control.

2. Can I drive my car with the P2643 code?

While it may be possible to drive the car with the P2643 code, it is essential to avoid prolonged driving or heavy loads. Driving in this condition can cause additional stress on the transmission, which can lead to further problems and damage.

3. What is the average cost to repair the P2643 code?

The cost to repair the P2643 code can vary depending on the root cause of the issue. On average, the cost can range from $200 to $400 for parts and labor. In some cases, the cost can be higher if the issue requires more extensive repairs or parts replacement.

4. How can I prevent the P2643 code from happening?

To prevent the P2643 code from happening, it is essential to maintain a regular maintenance schedule for your car. This includes checking and changing the transmission fluid, checking the connections and wires, and performing software updates as recommended by the manufacturer.

5. Can I fix the P2643 code myself?

While it is possible to fix the P2643 code yourself, it is recommended to seek professional help. Diagnosing and repairing transmission issues can be complex and require specialized knowledge and equipment. A professional mechanic can ensure that the repair is complete and safe.


In conclusion, the P2643 code is an OBD-II error code that is related to the torque management feedback signal B low. This code is set when the PCM detects an issue with the feedback signal from the TCC. To diagnose and repair this issue, it is essential to follow a few steps, such as checking the wires, connectors, and the TCC solenoid. If you have any doubts or concerns about the P2643 code, it is best to seek help from a professional mechanic. By addressing the issue promptly, you can avoid more severe transmission issues and ensure that your car operates safely and efficiently.

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