Bank1 Sensor 1 replacement

2005 Sienna with 130,000 miles



On way back from 300 mile road trip, CEL light popped on last night. Took it to Autozone this morning to pull the codes. It was a few key cycles before we could get the OBDII reader to communicate with the vehicle. By then, the CEL had gone out. So, we put it on a live reader, and could see that the voltage of Bank 1 Sensor 1 O2 sensor was really high...like 3.5V. The other two sensors were still hanging around under 1 volt. So, with not entirely complete information, I'm betting the Bank 1 Sensor 1 O2 sensor needs to be replaced.



Could someone tell me the location of Bank 1 Sensor 1, how difficult is it to get to, and recommend a decent O2 sensor brand/model to replace it?



Thanks in advance.

Reply 1 : Bank1 Sensor 1 replacement

OK...learned this much.



Sensor 1 means that this is an upstream sensor, which I'm guessing will be in fairly close proximity to the exhaust manifolds.



Bank 1 (as opposed to Bank 2) means that this is the sensor that handles Cylinder 1, 3, & 5. Can someone please confirm that 1/3/5 cylinders are the firewall side of the engine or the radiator side?



So, the difficulty on getting to this? Do you get to this sensor from the engine bay or from underneath? I was just about to change the spark plugs which will entail pulling out the plenum (or so I have been lead to believe). If the sensor is in the same location, I could get both done at the same time.



Suggestions on sensor brand/model or is it preferred to use a Toyota OEM part?

Reply 2 : Bank1 Sensor 1 replacement

Got the information from tech. 135 are closest to the firewall, and 246 are on the radiator side.