FAULTBASE
NEWSASKCars
© 2025 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
Home/Cars/Toyota/Corolla/E170 (2013-2019)/why is my Toyota Corolla E170 (2013-2019) check engine light on with code P0420

why is my Toyota Corolla E170 (2013-2019) check engine light on with code P0420

Toyota Corolla E170 (2013-2019)

Severity: mediumDifficulty: mediumError Code: P04202-4 hours
3 min read
579 words

Problem Statement

Learn how to diagnose and fix P0420 catalytic converter efficiency issue in Toyota Corolla E170. 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 vehicle to cool down before working on the exhaust system to prevent burns.

Symptoms

  • •Check engine light illuminated
  • •Decreased fuel economy
  • •Rough engine idle
  • •Failed emissions test
  • •Unusual exhaust smell (sulfur or rotten egg odor)

Diagnostic Steps

  1. 1Scan for additional error codes using an OBD-II scanner to confirm P0420 and identify any related codes.
  2. 2Inspect the exhaust system for any visible leaks or damage that could affect the catalytic converter's performance.
  3. 3Check the oxygen sensors (upstream and downstream) for proper operation using a multimeter or scan tool.
  4. 4Measure the temperature difference between the inlet and outlet of the catalytic converter to assess its efficiency.
  5. 5Inspect the engine for vacuum leaks that could lead to incorrect air-fuel mixture affecting catalytic converter performance.
  6. 6Verify the fuel trim readings to ensure they are within normal parameters.

Solution

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

  • Sub-steps:
    1. Locate the upstream and downstream oxygen sensors in the exhaust system.
    2. Use an O2 sensor socket to unscrew and remove the sensors.
    3. Inspect the sensors for signs of damage or contamination.
    4. Install new oxygen sensors, ensuring they are correctly torqued to manufacturer specifications (typically around 30 lb-ft).
    5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

  • Sub-steps:
    1. Remove any heat shields covering the catalytic converter.
    2. Unbolt the catalytic converter from the exhaust pipes, using a socket set.
    3. Inspect the catalytic converter for physical damage or signs of clogging (e.g., rattling sound).
    4. Install the new catalytic converter, ensuring proper alignment and sealing.
    5. Torque the bolts to the manufacturer's specifications (typically around 30 lb-ft for exhaust bolts).
    6. Reinstall the heat shields.

4. Clear Codes and Test Drive

  • Sub-steps:
    1. Reconnect the battery.
    2. Use an OBD-II scanner to clear the P0420 code from the vehicle's computer.
    3. Start the engine and allow it to warm up.
    4. Test drive the vehicle under various conditions to ensure the check engine light does not return.

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
  • Screwdrivers

Parts Required

  • Upstream oxygen sensor
  • Downstream oxygen sensor
  • Catalytic converter (if needed)

Additional Information

Error CodeP0420
Component

Exhaust System

Repair Time

2-4 hours

Difficulty

medium

Severity

medium

Tools

5 items

Parts

3 items

Related Faults

Discover similar issues

  1. what should I do if my Toyota Corolla E170 (2013-2019) has a steering issue after a recall?

    Learn how to diagnose and fix steering issues after a recall for your Toyota Corolla E170 (2013-2019). Step-by-step guide with diagnostic procedures a...

    Component:Steering
    Symptoms
    • •Steering wheel feels loose or unresponsive
    • •Increased steering effort required
    • +{count} more
  2. what should I check if my Toyota Corolla E170 (2013-2019) has a warning light for power steering?

    Learn how to diagnose and fix the power steering warning light issue in a 2013-2019 Toyota Corolla E170. Step-by-step guide with diagnostic procedures...

    Component:Steering
    Symptoms
    • •Power steering warning light illuminated on the dashboard
    • •Difficulty steering, especially at low speeds
    • +{count} more
  3. why does my Toyota Corolla E170 (2013-2019) make a squeaking noise when steering?

    Learn how to diagnose and fix squeaking noise when steering in Toyota Corolla E170 (2013-2019). Step-by-step guide with symptoms, diagnostic steps, an...

    Component:Steering
    Symptoms
    • •Squeaking noise when turning the steering wheel
    • •Noise increases with steering input
    • +{count} more
  4. Transmission overheating Corolla E170

    Learn how to diagnose and fix transmission overheating issues in Toyota Corolla E170 models (2013-2019) with this comprehensive guide.

    Component:transmission
    Symptoms
    • •Transmission temperature warning light illuminated
    • •Sluggish acceleration
    • +{count} more
  5. how to fix a stiff steering wheel in my Toyota Corolla E170 (2013-2019)

    Learn how to diagnose and fix a stiff steering wheel in your 2013-2019 Toyota Corolla E170. Step-by-step guide with symptoms, diagnostic steps, and re...

    Component:Steering
    Symptoms
    • •Difficulty turning the steering wheel
    • •Increased effort required to steer
    • +{count} more
  6. Battery not charging Toyota Corolla E170

    Learn how to diagnose and fix battery charging issues in Toyota Corolla E170 models. Follow these steps to ensure your vehicle's charging system is fu...

    Component:charging system
    Symptoms
    • •Battery warning light illuminated on the dashboard
    • •Dimming headlights or interior lights
    • +{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