2000 Toyota 4Runner P0420 - Catalyst Efficiency Below Thres

2000 TOYOTA 4RUNNER
126,000 MILES • 6 CYL • 4WD • AUTOMATIC
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LEOGIRL
  • MEMBER
  • 1 POST
P0420 - Catalyst Efficiency Below Threshold Bank 1 message dor check engine light.

REPAIRS ALREADY COMPLETED

Catalytic converter(s) two for this model - new
Oxygen Sensor - new
Fuel Filter - new
Battery - new

All repairs completed within past 2 months with same check engine message remaining.

What else needs to be done? We do not know what to fix next and neither does our mechanic! Please advise
Jan 12, 2010 at 8:22 AM
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SERVICE WRITER
  • ✓Experienced Mechanic
  • 9,123 POSTS
A leak ahead of the cat can cause this code. I am sure that was checked.

The toyotas are fussy. Were the cats and O2s that were replaced from the dealer?

If not what brand. There is a difference in this case.


Was the MAF cleaned? Should try if not.
Jan 12, 2010 at 11:16 AM
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