Toyota Repair: Seat belt and tire pressure lights, correct tire pressure, oxygen sensor

Question
Hi! I have a 1998 sienna. My seat belt light is on all the time. And my tire pressure light turned on and off frequently even I have correct tire pressure. I reseted it but I still have problem. I have a multimeter. Can you show me how to troubleshoot?

My second car is 2001 Tundra 8 cylinders and MIL is on. I pulled the code and found that the heater circuit of  oxygen sensor after the CAT on passenger side is bad. the heater resistance check shown that it is open. I would like to know how this gonna effect the engine performance. Thank you so much!

Answer
there is a button at the bottom of the dash. Press and hold with the emergency brake on. The light will flash three times, then go out.

The buckle switch is probably ng. unplug under the seat and check it at that connection.

Yes it will, as the feedback it gives to the ECU is what sets injection duration. Replace it.

Mike