Sensor

Hello tw!

looking under my truck it seems like i have a secondary sensor and it is connected to some stock muffler. I thought the 2rz single cabs had only 1 sensor and thats before the cat. And do yall know where it routes through? Im stumped because it is quite different from the sensor before the cat. Looks like it just goes into the bed of my truck

 

It needs one pre and one post cat to work

 

Oh okay. And where does it plug into? Its not like the one for the pre cat where it clips off. Maybe thats why im getting a p0420 code

 

It goes inside and is under the carpet.

It's likely fine and you should expect a catalytic converter in your future.

p0420 only triggers if both o2 sensors are operating properly.

Check for exhaust leaks as a preliminary check.

 

@Bishop84 oh okay never changed the rear one though. First it all began with my pre cat sensor, then after relplacing it it threw a p0420 hmmm. Thank god theres no emissions in florida. You think the pre cat sensor is most important? Stupid question i know im just curious

 

Under passenger seat carpet

 

The first O2 sensor controls the air-fuel ratio. The second O2 sensor checks the catalytic converter--no effect on the way the engine runs. If waveforms from both O2 sensors match it's as if the exhaust is going through a straight pipe and the computer throws the code assuming the cat isn't working. If the cat is working correctly then the unburned fuel and oxygen get combined in the cat and the rear O2 sensor has a different waveform from the first, which would be normal. It should be less wavy, more of a straight line. Ideally, you only have H2O, CO2 and N2 after the cat.

If you replaced the front O2 sensor, then you may have had some built up soot in the cat if the air-fuel ratio had been off. I'd clear the code and give it an Italian tune-up to try to burn anything off the cat. If the P0420 keeps coming back quickly after clearing code, then consider replacing the O2 sensor. And if it still comes back, then maybe you need a cat. It could also be an exhaust leak. There seems to be a lot of false alarms with P0420.