Hi! I’ll write a brief description of what’s going on.

A few months ago, I got a check engine light saying that my catalytic converters were not efficient. My car has nearly 200,000 miles so it made sense. I replaced all three catalytic converters along with the hardware and gaskets. The only problem I had was the exhaust pipe that mounts to both the catalytic converters and joins them into the third did not lineup quite right with both cats just by a quarter inch but just enough to where I had to really force it on. I could tell the welds on the catalytic converters were super bad so I am figuring the welds were out out of tolerance, which is why my exhaust pipe didn’t lineup very well. It felt great for a few weeks, but then I got a check engine light saying that my oxygen sensors were bad. So I replaced those with some Bosch sensors and it resolves that previous code but now I am getting a code on both downstream sensors saying low-voltage. They are brand new sensors so I know that it’s not the sensor. The wiring pigtails aren’t an amazing shape. I read that a low-voltage code can be caused by a lean fuel mixture, vacuum leak, exhaust leak or a bad sensor/wiring. I noticed that the pipe that joins the two catalytic converters off the engine is really old and has some cracking. Is it possible that this low-voltage code can be caused from an exhaust leak after the downstream sensor? I was under the assumption that it would just have to be before the sensor like where it mounts to my engine. I think it’s strange how both my downstream sensors are showing the same code (P137, 157). What are your thoughts?