how to fix P0420 code on Tesla Outback 5th Generation (2015-2019)

Subaru Outback 5th Generation (2015-2019)

Error Codes

3-5 hours

Time

medium

Difficulty

high

Severity

Error Code: P0420

3 min read

530 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix P0420 catalytic converter efficiency issue in Subaru Outback (2015-2019). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0420

Affected Component

Exhaust System

Estimated Time

3-5 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.
•Allow the exhaust system to cool before inspection or repair to avoid burns.

Symptoms

•Check engine light illuminated
•Decreased fuel efficiency
•Engine stalling or rough idle
•Poor acceleration
•Excessive exhaust emissions
•Failed emissions test

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm P0420 and check for additional codes.
2
Inspect the exhaust system visually for any visible signs of damage or leaks.
3
Check the oxygen sensor operation by monitoring voltage output with a multimeter.
4
Measure the temperature difference between the inlet and outlet of the catalytic converter using a thermocouple.
5
Inspect the catalytic converter for physical damage or signs of clogging.
6
Verify engine performance and fuel trim data while observing live data on the OBD-II scanner.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

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

Prevention Tips

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

Tools & Equipment Required

•OBD-II scanner
•Oxygen sensor socket
•Socket set
•Torque wrench
•Thermocouple

Parts Required

•Upstream oxygen sensor
•Downstream oxygen sensor
•Catalytic converter
•Exhaust gaskets

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Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm P0420 and check for additional codes.
2
Inspect the exhaust system visually for any visible signs of damage or leaks.
3
Check the oxygen sensor operation by monitoring voltage output with a multimeter.
4
Measure the temperature difference between the inlet and outlet of the catalytic converter using a thermocouple.
5
Inspect the catalytic converter for physical damage or signs of clogging.
6
Verify engine performance and fuel trim data while observing live data on the OBD-II scanner.

Solution

1. Preparation

Gather tools and parts required for the repair.
Disconnect the vehicle's battery to prevent electrical shorts.
Allow the engine to cool before starting work.

2. Inspect and Replace Oxygen Sensors

Sub-steps:
1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Disconnect the electrical connectors from both oxygen sensors.
3. Remove the sensors using an oxygen sensor socket.
4. Install new oxygen sensors (ensure they are the correct type for your vehicle).
5. Reconnect the electrical connectors to the sensors.

3. Check and Replace the Catalytic Converter

Sub-steps:
1. Locate the catalytic converter in the exhaust system.
2. Remove any heat shields or brackets securing the catalytic converter.
3. Unbolt the catalytic converter from the exhaust pipes using a socket set (note torque specifications).
4. Inspect the exhaust pipes for damage or blockages.
5. Install the new catalytic converter, ensuring proper alignment and sealing with gaskets.
6. Tighten all bolts to the manufacturer’s torque specifications.

4. Clear Codes and Test Drive

Sub-steps:
1. Reconnect the battery.
2. Use the OBD-II scanner to clear the P0420 code.
3. Take the vehicle for a test drive under various conditions (highway, city).
4. Monitor for reoccurrence of the check engine light.