my BMW X3 G01 (2018-2024) has a check engine light and emissions failure

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Address Faulty Oxygen Sensors

1. Locate the oxygen sensors in the exhaust system (pre-catalytic and post-catalytic).
2. Disconnect the electrical connectors from the sensors.
3. Use a socket wrench to remove the defective sensors.
4. Install new oxygen sensors and torque them to the manufacturer’s specifications (generally around 30-40 Nm).
5. Reconnect the electrical connectors.

3. Replace or Repair Catalytic Converter (if necessary)

1. Inspect the catalytic converter for damage or excessive carbon build-up.
2. If replacement is needed, unbolt the catalytic converter from the exhaust system.
3. Install the new catalytic converter and torque the bolts to the specified value (usually 25-30 Nm).
4. Ensure all gaskets are replaced and seals are tight.

4. Repair EGR System (if needed)

1. Locate the EGR valve and inspect for clogging.
2. Remove any build-up using an appropriate cleaning solution and brush.
3. If the valve is faulty, disconnect it and unbolt it from the engine.
4. Install a new EGR valve and torque bolts to manufacturer specifications.

5. Final Assembly and Testing

1. Reconnect the negative battery terminal.
2. Clear any error codes using the OBD-II scanner.
3. Start the engine and allow it to reach operating temperature.