How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Eric Your Own Question
Eric, Automotive Repair Shop Manager
Category: Toyota
Satisfied Customers: 31900
Experience:  20+ yrs. experience as repair shop manager and technician.
Type Your Toyota Question Here...
Eric is online now
A new question is answered every 9 seconds

2003 toyota matrix: catalyst..what needs to be done to repair

Resolved Question:

2003 toyota matrix code p0420 catalyst deficiency what needs to be done to repair
Submitted: 7 years ago.
Category: Toyota
Expert:  Eric replied 7 years ago.



Here are the possible causes of DTC P0420:


  • failed catalytic converter
  • exhaust leak between the exhaust manifold and the converter
  • damaged O2 sensor wiring harness after the converter(downstream O2).

You can visually check for chafed or burned wiring harness on the downstream O2 sensor. If damaged, that wiring harness will need to be replaced


Open hood and let engine idle and listen to exhaust sound. Now stuff an old rag or towel in the tailpipe and listen to exhaust again in the engine compartment. if it increases, then the exhaust will need to be repaired.


If all the above are ok, then it has to have a new catalytic converter, followed by a computer reprogramming.


Catalytic Converters are covered by a Federal Emissions Warranty for 8yrs or 80,000 miles, which ever comes first

Eric and 6 other Toyota Specialists are ready to help you

Related Toyota Questions