I recently had the inevatable Check Engine light come on and upon checking the code (P1193) I found out it was HO2S heater circuit inferred open circuit, downstream circuit. I recently changed one of the downstream sensors and am wondering if it is the other one. Do I need a new one? How do I check if it is out of parameters? Could it just need to be cleaned or is it the wiring to the sensor? Appreciate any help...

 

Why did you recently replace the sensor? Was it actually bad? If so, did you use an OEM replacement?


The reason I ask, is that I have not had real good luck with the non-OEM sensors.

From a testing standpoint, the first thing I would do is pull the plug apart on both downstream sensors and measure continuity/resistance with a multimeter.