Toyota Car Error Code P0420
Catalyst Below Threshold Bank 1
Severity
DIY Difficulty
Est. Cost
$100 - $1500
Est. Time
120 min
What Does P0420 Mean?
Toyota car error P0420 means catalyst below threshold bank 1. This is a significant issue with a DIY difficulty of 4/5. Most repairs cost between $100 and $1500.
Common Causes
Component wear
This is a potentially significant cause of the P0420 error on Toyota cars.
Blockage
This is a potentially significant cause of the P0420 error on Toyota cars.
Sensor failure
This is a potentially significant cause of the P0420 error on Toyota cars.
Wiring issue
This is a potentially significant cause of the P0420 error on Toyota cars.
Step-by-Step Fix
Power cycle the appliance
Unplug your Toyota car for 60 seconds, then plug it back in. This clears temporary errors and resets the control board.
Check for obvious issues
Inspect your car for any visible problems such as loose connections, blockages, or unusual sounds. Many P0420 errors on Toyota units are caused by simple issues.
Run a diagnostic cycle
Many Toyota cars have a built-in diagnostic mode. Check your user manual for the specific key combination to enter diagnostics on your model.
Test related components
Based on the P0420 error meaning (Catalyst Below Threshold Bank 1), check the specific components involved. Use a multimeter to test for continuity if you are comfortable with electrical testing.
Contact a professional
If the above steps do not resolve the P0420 error, contact a certified Toyota technician. This repair has a difficulty rating of 4/5 and may require specialized tools.
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