my Ram 1500 DT (2019-Present) has a P0421 code, what does it mean?

• •Check engine light illuminated
• •Poor fuel economy
• •Reduced engine performance
• •Increased emissions
• •Engine stalling or hesitation during acceleration

1. 1Scan for additional error codes using an OBD-II scanner to identify any related issues.
2. 2Inspect the exhaust system for leaks or damage that could affect sensor readings.
3. 3Check the oxygen sensors’ operation by using a multimeter to measure voltage output.
4. 4Verify the fuel trim readings to assess if the engine is running too rich or too lean.
5. 5Inspect the catalytic converter for any signs of blockage or damage.
6. 6Examine the wiring and connectors for the oxygen sensors for corrosion or loose connections.

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

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

• •OBD-II scanner
• •Oxygen sensor socket
• •Torque wrench
• •Exhaust tape or pipe repair kits

• •Oxygen sensor (upstream/downstream as necessary)
• •Catalytic converter (if required)