2002 Sienna CE with 200,000 miles. a months ago, the check engine light went on, with code P0420.
At the same time, I heard the typical exhaust leaking sound. So I went under the vehicle, and found the downstream O2 sensor is loose - the mounting bolt is completely rusted away. So I temporarily wrapped the sensor back tightly with steel wires, and then cleared the code. But a week later it came back.
A search points to upstream O2 sensor on bank 1. But when I tried to purchase an O2 sensor, the listing says "A/F and O2 sensor", so I'm confused.
I got the same code 8 years back, I replaced the two sensors mounted on the exhaust manifold, one in the front engine bay, which was easy to replace, another under the vehicle and have to be removed with a special socket. The OEM sensors cost $200 each and of difference part numbers, not sure if they are any different from each other. I also learned then that Bank 1 is the one from under the vehicle, the one at the front is Bank2. Today non-OEM parts are far cheaper.
My question is: what is the difference between O2 sensor and A/F sensor. Are the ones mentioned above A/F sensor or O2 sensor? the Clifton repair manual says they look the same without saying what each is for. That confused me even more.
Can some explain a bit what the difference are?
thanks much!
At the same time, I heard the typical exhaust leaking sound. So I went under the vehicle, and found the downstream O2 sensor is loose - the mounting bolt is completely rusted away. So I temporarily wrapped the sensor back tightly with steel wires, and then cleared the code. But a week later it came back.
A search points to upstream O2 sensor on bank 1. But when I tried to purchase an O2 sensor, the listing says "A/F and O2 sensor", so I'm confused.
I got the same code 8 years back, I replaced the two sensors mounted on the exhaust manifold, one in the front engine bay, which was easy to replace, another under the vehicle and have to be removed with a special socket. The OEM sensors cost $200 each and of difference part numbers, not sure if they are any different from each other. I also learned then that Bank 1 is the one from under the vehicle, the one at the front is Bank2. Today non-OEM parts are far cheaper.
My question is: what is the difference between O2 sensor and A/F sensor. Are the ones mentioned above A/F sensor or O2 sensor? the Clifton repair manual says they look the same without saying what each is for. That confused me even more.
Can some explain a bit what the difference are?
thanks much!