P0420 on 2020 TOYOTA Tundra

“I have read shifty's links on P0420. Here's some background info: - Upstream o2 on both banks appear to have the normal fluctuations between lower and higher voltage - Downstream o2's mimic the upstream.”

“I just decided to try to swap bank 1 to bank 2 to see if the code follows, but the downstream on bank 2 has a short pigtale. Bank 1 has a long pigtale, so swapping won't be an option.”

“My problems start in the 20mph range and don’t get better til after 40mph. If I try to accelerate quickly it will downshift into a lower gear but not really go any faster.”

“If I try to accelerate quickly it will downshift into a lower gear but not really go any faster. It does begin to rattle at that point and I’ve seen a CEL come and go.”

“P0420 with dropping exhaust temperatures and lean fuel trim I hate to be that guy who asks about cat codes for the millionth time, but because so many smooth brains like me ask dumb questions I haven't been able to find a thread with similar problems as mine.”

“I don't know what spark plugs were used the but the guy I bought the truck from did things right. He used Toyota parts on everything so I'm betting he didn't cheap out on the plugs.”

“He used Toyota parts on everything so I'm betting he didn't cheap out on the plugs. The P0420 code is just "catalyist system efficiency below threshold (bank 1)".”

“I've had a recurring P0420 code. catalyst system efficiency of your car is below threshold (Bank 1) Now the light stays on. I just decided to try to swap bank 1 to bank 2 to see if the code follows, but the downstream on bank 2 has a short pigtale.”

“P0420 is the OBD telling you specifically that the O2 sensor downstream of the cat is sending a signal outside the allowed parameters. As others have said, swap your drivers and passengers side downstream O2 sensors.”

“You narrow it down by the code being given. P0420 is the OBD telling you specifically that the O2 sensor downstream of the cat is sending a signal outside the allowed parameters.”