FAULTBASE
NEWSASKCars
© 2025 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
Home/Cars/Subaru/Outback/5th Generation (2015-2019)/how to troubleshoot P0420 code on Tesla Outback 5th Generation (2015-2019)

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

Subaru Outback 5th Generation (2015-2019)

Severity: highDifficulty: mediumError Code: P04202-4 hours
3 min read
594 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 troubleshoot and fix P0420 exhaust system issue in 2015-2019 Subaru Outback. Step-by-step guide with diagnostic procedures and repair instructions.

Error Code
P0420
Component
Exhaust System
Repair Time
2-4 hours

Safety Warnings

  • ⚠Disconnect the battery before working on electrical components.
  • ⚠Allow the engine to cool before accessing the exhaust system to avoid burns.

Symptoms

  • •Check engine light illuminated
  • •Decreased fuel efficiency
  • •Poor acceleration or power loss
  • •Engine stalling or rough idle
  • •Increased emissions
  • •Unusual exhaust odor

Diagnostic Steps

  1. 1Scan the vehicle's onboard computer for error codes using an OBD-II scanner to confirm P0420 and check for any additional codes.
  2. 2Inspect the exhaust system for any visible leaks or damage, particularly around the catalytic converter and oxygen sensors.
  3. 3Check the oxygen sensor readings with a multimeter or scan tool to ensure they are within specification and responding correctly to changes in engine conditions.
  4. 4Measure the temperature before and after the catalytic converter using a thermometer or infrared temperature gun to compare readings.
  5. 5Verify that the engine is running at optimal conditions, including checking for vacuum leaks, fuel pressure, and ignition system performance.

Solution

Solution

1. Preparation

  • Gather necessary tools and parts.
  • Disconnect the negative battery terminal to prevent electrical surges.
  • Allow the vehicle to cool down before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

  • Tools Required: O2 sensor socket, torque wrench, penetrating oil.
  • Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  • Apply penetrating oil to the sensor threads and allow it to sit for a few minutes.
  • Use the O2 sensor socket to remove the faulty sensors.
  • Install the new sensors, tightening them to the manufacturer's specified torque (usually 30-40 ft-lbs).
  • Reconnect the battery terminal.

3. Inspect and Replace Catalytic Converter (if needed)

  • Tools Required: Socket set, jack stands, exhaust gasket.
  • Raise the vehicle and secure it on jack stands.
  • Unbolt the exhaust system at the catalytic converter using the socket set.
  • Remove any heat shields if necessary.
  • Inspect the catalytic converter for physical damage or blockage.
  • If replacement is required, install the new catalytic converter with an appropriate exhaust gasket.
  • Tighten all bolts to the manufacturer’s specifications.

4. Clear Codes and Test

  • Reconnect the battery terminal.
  • Use the OBD-II scanner to clear the P0420 code from the vehicle's memory.
  • Start the engine and allow it to reach operating temperature.
  • Test drive the vehicle under various conditions to ensure normal operation and check for the reappearance of the check engine light.

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
  • Socket set
  • O2 sensor socket
  • Torque wrench
  • Thermometer or infrared temperature gun
  • Jack stands

Parts Required

  • New upstream and downstream oxygen sensors
  • New catalytic converter (if required)
  • Exhaust gasket

Additional Information

Error CodeP0420
Component

Exhaust System

Repair Time

2-4 hours

Difficulty

medium

Severity

high

Tools

6 items

Parts

3 items

Related Faults

Discover similar issues

  1. how to check the transmission fluid level in a Tesla Outback 5th Generation (2015-2019)

    Learn how to check the transmission fluid level in a Tesla Outback (2015-2019). Step-by-step guide to ensure proper transmission function.

    Component:Transmission
    Symptoms
    • •Difficulty shifting gears
    • •Unusual transmission noises
    • +{count} more
  2. what causes oil leaks in Tesla Outback 5th Generation (2015-2019)?

    Learn how to diagnose and fix oil leaks in Tesla Outback 5th Generation (2015-2019). Step-by-step guide with symptoms, diagnostic steps, and repair in...

    Component:Engine
    Symptoms
    • •Visible oil spots or puddles under the vehicle
    • •Low oil level warning on the dashboard
    • +{count} more
  3. how to troubleshoot my Tesla Outback 5th Generation (2015-2019) if it stalls at stoplights

    Learn how to troubleshoot and fix engine stalling issues at stoplights in Tesla Outback 5th Generation (2015-2019). Step-by-step guide included.

    Component:Engine
    Symptoms
    • •Engine stalls when idling at stoplights
    • •Difficulty restarting the engine after a stall
    • +{count} more
  4. how to reset the service light on Tesla Outback 5th Generation (2015-2019)

    Learn how to reset the service light on a 2015-2019 Tesla Outback. Step-by-step guide with diagnostic procedures and reset instructions.

    Component:Electrical
    Symptoms
    • •Service light is illuminated on the dashboard
    • •Notification of maintenance due
    • +{count} more
  5. how to fix the AC not blowing cold air in my Tesla Outback 5th Generation (2015-2019)

    Learn how to diagnose and fix AC not blowing cold air in Tesla Outback 5th Generation. Step-by-step guide with symptoms, tools, and repair instruction...

    Component:HVAC
    Symptoms
    • •AC system does not cool the cabin air
    • •Reduced airflow from AC vents
    • +{count} more
  6. how to troubleshoot differential noise in my Tesla Outback 5th Generation (2015-2019)

    Learn how to troubleshoot and fix differential noise in Tesla Outback 5th Generation (2015-2019). Step-by-step guide with diagnostic and repair instru...

    Component:Transmission
    Symptoms
    • •Unusual whining or grinding noise when accelerating or decelerating
    • •Noise changes with vehicle speed, not engine speed
    • +{count} more

Share this solution

Comments

Sign in to share your thoughts

Sign In

No comments yet

Be the first to share your thoughts

Back to Generation