how to fix U0121 code in Renault Clio V (2019-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative terminal of the battery to prevent electrical shock.

2. Inspect Wiring and Connectors

• Tools Required: Wire strippers, multimeter, dielectric grease.
• Carefully disconnect the wiring harness from both the ECU and TCU.
• Inspect the connectors for bent pins, corrosion, or dirt.
• Use a multimeter to check continuity in the wiring between the ECU and TCU.
• Apply dielectric grease to the connectors before reconnecting to prevent moisture ingress.

3. Check Battery and Ground Connections

• Tools Required: Multimeter.
• Use a multimeter to check the battery voltage; it should be between 12.4V to 12.6V.
• Inspect and clean the ground connections on the chassis and engine.
• Ensure that the battery terminals are clean and securely tightened.

4. Inspect Fuses

• Tools Required: Fuse puller or pliers.
• Locate the fuse box and check the fuses related to the ECU and TCU.
• Replace any blown fuses with ones of the same rating.

5. Reconnect Battery and Test

• Reconnect the negative terminal of the battery.
• Start the vehicle and monitor for any warning lights or error codes.
• Test drive the vehicle to ensure that the transmission operates normally.