FAULTBASE
NEWSASKCars
© 2025 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
Home/Cars/Genesis/G70/IG (2017-2023)/how to fix P0420 code on my Genesis G70 IG (2017-2023)

how to fix P0420 code on my Genesis G70 IG (2017-2023)

Genesis G70 IG (2017-2023)

Severity: highDifficulty: mediumError Code: P04202-4 hours
3 min read
523 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 exhaust system issue in Genesis G70 (2017-2023). 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 systems.
  • ⚠Allow the engine to cool before working on the exhaust system.

Symptoms

  • •Check engine light illuminated
  • •Poor acceleration or loss of power
  • •Decreased fuel economy
  • •Unusual exhaust odors
  • •Engine misfires or rough idling

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm the P0420 code.
  2. 2Inspect the exhaust system for visible damage or leaks.
  3. 3Check the condition of the catalytic converter for any signs of physical damage or contamination.
  4. 4Measure the oxygen sensor voltage output using a multimeter while the engine is running.
  5. 5Inspect and test the upstream and downstream oxygen sensors for proper functionality.
  6. 6Check for any exhaust leaks before the catalytic converter.

Solution

Solution

1. Preparation

  • Gather all necessary tools and parts.
  • Disconnect the battery to ensure safety during repairs.
  • Allow the engine to cool down completely before starting work.

2. Inspect and Replace Oxygen Sensors

  1. Remove the upstream oxygen sensor:
    • Locate the upstream oxygen sensor (usually before the catalytic converter).
    • Use an oxygen sensor socket to remove the sensor.
  2. Install the new upstream oxygen sensor:
    • Apply anti-seize compound on the sensor threads if required.
    • Torque to the manufacturer's specifications (typically around 30 lb-ft).
  3. Repeat for the downstream oxygen sensor if needed:
    • Follow the same procedure for the downstream sensor.

3. Inspect and Replace the Catalytic Converter

  1. Remove the exhaust components:
    • Loosen and remove any bolts or clamps securing the catalytic converter.
    • Carefully detach the catalytic converter from the exhaust system.
  2. Install the new catalytic converter:
    • Position the new catalytic converter and align it with the exhaust pipes.
    • Secure with bolts or clamps, torquing to specifications (typically around 30-40 lb-ft).
  3. Reattach any heat shields or brackets if applicable.

4. Final Checks

  1. Reconnect the battery.
  2. Start the engine and let it idle for a few minutes.
  3. Check for any exhaust leaks around the installed components.

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
  • Ratchet and socket set
  • Torque wrench
  • Multimeter

Parts Required

  • Upstream oxygen sensor
  • Downstream oxygen sensor
  • Catalytic converter

Additional Information

Error CodeP0420
Component

Exhaust System

Repair Time

2-4 hours

Difficulty

medium

Severity

high

Tools

5 items

Parts

3 items

Related Faults

Discover similar issues

  1. my Genesis G70 has a hard time starting in the morning, what's wrong?

    Learn how to diagnose and fix hard starting issues in Genesis G70. Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

    Component:Electrical
    Symptoms
    • •Engine cranks slowly or not at all
    • •Battery warning light illuminated
    • +{count} more
  2. why does my Genesis G70 have a strong fuel odor after refueling?

    Discover how to diagnose and fix strong fuel odors after refueling in your Genesis G70. Step-by-step guide with symptoms, diagnostics, and solutions.

    Component:Fuel System
    Symptoms
    • •Strong fuel smell inside or outside the vehicle
    • •Fuel vapor smell near the fuel filler area
    • +{count} more
  3. my Genesis G70 has a fuel leak, how do I find it

    Learn how to diagnose and fix fuel leaks in Genesis G70. Step-by-step guide with symptoms, diagnostic steps, tools, and repair instructions.

    Component:Fuel System
    Symptoms
    • •Fuel odor around the vehicle
    • •Visible fuel stains or puddles under the car
    • +{count} more
  4. my Genesis G70 has a hard time shifting gears, what's wrong

    Learn how to diagnose and fix transmission shifting issues in Genesis G70. Step-by-step guide with symptoms, diagnostic steps, and repair instructions...

    Component:Transmission
    Symptoms
    • •Difficulty engaging gears (both upshifting and downshifting)
    • •Slipping transmission (engine revs without corresponding increase in speed)
    • +{count} more
  5. why does my Genesis G70 have a rough idle when warm

    Learn how to diagnose and fix rough idle issues in Genesis G70. Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

    Component:Engine
    Symptoms
    • •Rough idle at operating temperature
    • •Engine stalling at stoplights or during low-speed maneuvers
    • +{count} more
  6. my Genesis G70 struggles to accelerate, what's the issue

    Discover how to diagnose and fix acceleration issues in Genesis G70. Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

    Component:Engine
    Symptoms
    • •Engine stalling during acceleration
    • •Hesitation or lag when pressing the throttle
    • +{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