how to fix U0140 code in Tesla Outback 5th Generation (2015-2019)

Subaru Outback 5th Generation (2015-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

Error Code: U0140

3 min read

566 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix U0140 communication issues in Tesla Outback (2015-2019). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

U0140

Affected Component

Electrical

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems to avoid shocks or shorts.

Symptoms

•Check engine light illuminated
•Inoperative or malfunctioning electronic accessories (e.g., windows, locks)
•Intermittent loss of communication with other modules
•Warning messages on the dashboard
•Difficulty starting the vehicle

Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner to confirm the U0140 code and check for any additional codes.
2
Inspect the vehicle's wiring harness for any visible damage or corrosion, particularly around the BCM and connectors.
3
Verify the integrity of the BCM by checking for proper power and ground signals using a multimeter.
4
Check all related connectors for loose connections or corrosion, ensuring that they are seated properly.
5
Test the communication lines between the BCM and other modules for continuity and resistance.
6
Clear the codes and perform a test drive to see if the U0140 code returns.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•OBD-II scanner
•Multimeter
•Socket set
•Wire brush
•Dielectric grease

Parts Required

•Body Control Module (if replacement is necessary)
•Electrical connectors or wiring (if repairs are needed)

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Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner to confirm the U0140 code and check for any additional codes.
2
Inspect the vehicle's wiring harness for any visible damage or corrosion, particularly around the BCM and connectors.
3
Verify the integrity of the BCM by checking for proper power and ground signals using a multimeter.
4
Check all related connectors for loose connections or corrosion, ensuring that they are seated properly.
5
Test the communication lines between the BCM and other modules for continuity and resistance.
6
Clear the codes and perform a test drive to see if the U0140 code returns.

Solution

1. Preparation

Gather tools and parts needed for the repair.
Disconnect the negative terminal of the battery to prevent electrical shorts.
Tools Required: OBD-II scanner, multimeter, socket set, wire brush, dielectric grease.

2. Inspect Wiring and Connections

Sub-step 1: Visually inspect the wiring harness connected to the BCM for any fraying, cuts, or corrosion.
Sub-step 2: Clean any corroded connectors using a wire brush and apply dielectric grease to prevent further corrosion.
Sub-step 3: Ensure all connectors are securely seated and free from moisture.

3. Test BCM Functionality

Sub-step 1: Reconnect the battery and power on the vehicle.
Sub-step 2: Use a multimeter to check for proper power (usually around 12V) at the BCM terminals. Refer to the service manual for specific pin locations.
Sub-step 3: Check for ground continuity at the BCM; it should read close to zero resistance.

4. Repair or Replace Components

Sub-step 1: If wiring damage is found, repair the affected sections by splicing in new wire and securing with electrical tape.
Sub-step 2: If the BCM is determined to be faulty, remove it by unscrewing the mounting screws and disconnecting the harnesses.
Sub-step 3: Replace the BCM with a new or refurbished unit, and reconnect all harnesses firmly.

5. Final Checks

Sub-step 1: Clear any stored codes using the OBD-II scanner after making repairs.
Sub-step 2: Perform a test drive to ensure all systems are functioning correctly and monitor for the return of the U0140 code.