Review on 🔥 Enhance Engine Performance with Denso 234-4516 OE Heated 4-Wire Downstream Oxygen Sensor 15.75” by Mark Gilbert

Had a code, P0420: Catalytic System Efficiency Below Threshold (Bank 1). This is the bottom sensor that is easily accessible under the car. I had to strain my neck to see the upper exhaust manifold sensor and pray I didn't have to replace that sensor. Easy to replace oxygen sensor. For the 2004 Sienna it is recommended to remove the console trim using the accelerator pedal to access the wiring connector (pull out the two locking pins). The sensor comes with a rubber grommet on the cable to seal the hole where the cable enters the van. Didn't even clear the code, drove a few days and the CEL light went out on its own!