how to check for a bad catalytic converter in Honda Civic 10th Generation (2016-2021)

Solution

1. Preparation

• Tools Required: OBD-II scanner, infrared thermometer, exhaust pressure gauge, safety goggles, gloves.
• Ensure the vehicle is parked on a level surface and the engine is off.
• Disconnect the negative battery terminal to ensure safety during inspection.

2. Scan for Error Codes

• Connect the OBD-II scanner to the vehicle's diagnostic port.
• Turn the ignition to the "ON" position without starting the engine.
• Retrieve and record any diagnostic trouble codes (DTCs) related to the catalytic converter (e.g., P0420).

3. Temperature Check

• Start the engine and allow it to warm up to operating temperature.
• Use the infrared thermometer to measure the temperature at the inlet of the catalytic converter.
• Measure the temperature at the outlet of the catalytic converter.
• A significant difference (typically over 100°F) indicates potential blockage or failure.

4. Backpressure Test

• Locate the oxygen sensor upstream of the catalytic converter and remove it.
• Insert the exhaust pressure gauge into the sensor port.
• Start the engine and measure exhaust backpressure at idle; it should be below 1.5 psi.
• If backpressure exceeds specifications, the catalytic converter may be clogged.

5. Emissions Analysis

• If available, use an emissions analyzer to check the vehicle's emissions.
• Compare the readings to manufacturer specifications.
• Elevated levels of pollutants can indicate a failing catalytic converter.

6. Oxygen Sensor Inspection

• Visually inspect the upstream and downstream oxygen sensors for damage.
• Use a multimeter to test the sensors' voltage output while the engine is running.
• Replace any faulty sensors, as they can affect catalytic converter performance.