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Re: check engine light
The 02 sensors are information sorces for the fuel system.The problem may not have been the sensors.I would take it to a known garage to have them scan it to see why it is putting up the 02 sensor code.
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Try this before buying anything. (seeing this alot lately) Run tank down to near empty and have Autozone reset the light then fill with a good brand name fuel. Cheap fuel/gas going around is triggering false O2 sensor warnings. (Had 2 this week alone)
If you can post the exact code that was read with the check engine light it may help with diagnosis. Toyota sensors should be replaced with Denso brand. Many other brands can create problems with Toyotas, especially Bosch.
I have the same vehicle, same code P0421, changed the BOTH O2 sensors and the check engine light was still on, took it to my fathers garage and checked the Catalytic Converter, and it was ok later I found out that P0421 means that the vehicle doesn't have the proper mixture of gas and air (running richer) so I changed the MAX air flow sensor and wala the code went away.
Sensor Contamination Inspection
Visually/physically inspect following items:
Remove and inspect the HO2S(B1S1) for any silicon contamination. This contamination will be indicated by a white powdery coating and this will result in a but false voltage signal.
Check MAFS for contamination, deterioration, or damage.
If contamination is evident on the HO2S or MAFS, replace contaminated sensor and go to next step.
The P0141 code points to the O2 sensor heater circuit. It could be that there is a short in the wiring to the O2 sensor or it could be that the O2 sensor heating element itself is bad. The code is for O2 sensor Bank 1 Sensor 2. Bank 1 means its the O2 sensor connected to the exhaust pipe that runs to cylinder #1. Sensor 2 means that it is likely the O2 sensor after the catalytic converter on the same exhaust pipe.