how to fix the P0420 code on my Renault Clio V (2019-Present)

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Remove the upstream (pre-catalytic) oxygen sensor:
  1. Locate the upstream O2 sensor on the exhaust manifold.
  2. Use the O2 sensor socket to unscrew the sensor.
  3. Inspect the sensor for damage.
  4. If necessary, replace with a new OEM sensor. Torque to manufacturer specifications (typically around 30 Nm).
• Repeat the process for the downstream (post-catalytic) oxygen sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust gasket
• Remove the catalytic converter:
  1. Locate the catalytic converter in the exhaust system.
  2. Unbolt the flanges connecting it to the exhaust pipe and manifold.
  3. Inspect for physical damage or clogging.
  4. Replace with a new catalytic converter if damaged. Make sure to use a gasket at the connection points.
  5. Torque the bolts to specifications (usually around 25 Nm).

4. Clear Codes and Test Drive

• After repairs, reconnect the battery.
• Use an OBD-II scanner to clear the P0420 code from the system.
• Test drive the vehicle to ensure the check engine light does not reappear.