2000 Toyota 4Runner P0420 - Catalyst Efficiency Below Thres

LEOGIRL

MEMBER
2000 TOYOTA 4RUNNER
6 CYL
4WD
AUTOMATIC
126,000 MILES

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

1 Reply

SERVICE WRITER

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.