FAULTBASE
NEWSASKCars
© 2025 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
Home/Cars/Tesla/Model 3/Highland (2024-present)/how to fix a P0420 code in my Tesla Model 3 Original (2017-2023)

how to fix a P0420 code in my Tesla Model 3 Original (2017-2023)

Tesla Model 3 Highland (2024-present)

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

Problem Statement

Learn how to diagnose and fix P0420 electrical issue in Tesla Model 3. Step-by-step guide with diagnostic procedures and repair instructions.

Error Code
P0420
Component
Electrical
Repair Time
2-4 hours

Safety Warnings

  • ⚠Disconnect the 12V battery before working on electrical systems.
  • ⚠Always follow manufacturer guidelines when handling high voltage components.

Symptoms

  • •Check engine light illuminated
  • •Reduced driving range
  • •Poor acceleration
  • •Increased energy consumption
  • •Battery management system warning

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm the P0420 code and check for any additional codes.
  2. 2Inspect the battery management system for any errors or faults.
  3. 3Check the voltage and current of the battery cells using a multimeter.
  4. 4Examine the high voltage connections and wiring for signs of damage or corrosion.
  5. 5Review the software version of the vehicle to ensure it is up-to-date.
  6. 6Perform a visual inspection of the vehicle's exhaust system to check for any signs of leaks or damage.

Solution

Solution

1. Preparation

  • Tools Required: OBD-II scanner, multimeter, torque wrench, basic hand tools.
  • Ensure the vehicle is parked on a flat surface and that the parking brake is engaged.
  • Disconnect the 12V battery to prevent any electrical hazards.

2. Update Software

  • Connect the vehicle to Wi-Fi.
  • Go to the settings menu on the vehicle’s touchscreen.
  • Check for software updates and install if available.
  • Reconnect the 12V battery after updating.

3. Inspect and Test Battery Cells

  • Reconnect the vehicle to the charging station.
  • With the multimeter, measure the voltage of each individual battery cell.
  • If any cell is significantly lower than others, consider replacing the faulty cell.

4. Check Wiring and Connectors

  • Inspect high voltage wiring for signs of wear, nicks, or corrosion.
  • Ensure all connectors are secure and free from corrosion.
  • Repair or replace any damaged wiring or connectors.

5. Clear Codes and Retest

  • Use the OBD-II scanner to clear the P0420 code.
  • Take the vehicle for a test drive under various conditions (highway and city).
  • After the drive, scan for codes again to ensure the issue is resolved.

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
  • Multimeter
  • Torque wrench
  • Basic hand tools

Parts Required

  • Replacement battery cells (if required)
  • High voltage wiring (if damaged)

Additional Information

Error CodeP0420
Component

Electrical

Repair Time

2-4 hours

Difficulty

medium

Severity

medium

Tools

4 items

Parts

2 items

Related Faults

Discover similar issues

  1. why does my Tesla Model 3 Highland (2024-present) engine oil smell burnt

    Discover how to diagnose and resolve burnt smell from engine oil in Tesla Model 3 Highland. Step-by-step guide with symptoms and solutions.

    Component:Engine
    Symptoms
    • •Check engine light illuminated
    • •Unusual engine noise or knocking
    • +{count} more

  2. why is my Tesla Model 3 Highland (2024-present) making a popping noise from the suspension

    Learn how to diagnose and fix popping noise from suspension in Tesla Model 3 Highland. Step-by-step guide with diagnostic procedures and repair instru...

    Component:Suspension
    Symptoms
    • •Popping or clunking noise when driving over bumps or uneven surfaces
    • •Noise occurs during acceleration or deceleration
    • +{count} more

  3. why does my Tesla Model 3 Highland (2024-present) make a thumping noise when driving

    Learn how to diagnose and fix thumping noise in Tesla Model 3 Highland. Step-by-step guide with diagnostic procedures and repair instructions.

    Component:Suspension
    Symptoms
    • •Thumping noise that varies with speed
    • •Possible vibration felt through the steering wheel or floor
    • +{count} more

  4. how to troubleshoot Tesla Model 3 Highland (2024-present) failing battery

    Learn how to troubleshoot and fix battery issues in Tesla Model 3 Highland (2024-present). Step-by-step guide with diagnostic procedures and repair in...

    Component:Electrical
    Symptoms
    • •Battery range significantly reduced
    • •Frequent alerts regarding battery health
    • +{count} more

  5. why does my Tesla Model 3 Highland (2024-present) make a beeping sound when I park

    Discover why your Tesla Model 3 Highland beeps when parking and how to resolve it. Step-by-step guide for diagnosing and fixing the issue.

    Component:Electrical
    Symptoms
    • •Beeping sound occurs during parking
    • •Possible visual alerts on the dashboard
    • +{count} more

  6. why does my Tesla Model 3 Highland (2024-present) brake pedal go all the way to the floor?

    Learn how to diagnose and fix the brake pedal going to the floor in Tesla Model 3 Highland. Step-by-step guide with symptoms, diagnostics, and repair ...

    Component:Brakes
    Symptoms
    • •Brake pedal feels excessively soft or spongy
    • •Brake warning light illuminated on the dashboard
    • +{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