Bank 1 system to lean

I have a 02 Tacoma 3.4 with CEL on, code says bank 1 system to lean, no modifications on this truck. Trying to find the right O2 sensor for this problem, Any suggestions?

 

it doesn't specify 1 or 2 sensor? just a bank 1

 

change them both your motor will run more efficient on both sides.

 

Ya don't oem are 150+ that's a 300 dollar blanket

 

http://www.lieblweb.com/o2replacement.html

It doesn't specify which one. When I did mine....I checked the 'continuity' and found a problem with Bank 1 Sensor 1.
Due to being closer to the engine & CAT - I think Bank 1 sensor 1 is prone to failing sooner.

 

The only sensor that actually monitors fuel trim is the 1st one. The second sensor is used to measure catalyst efficiency. So am engine being lean or rich is based on Bank "X" sensor 1. Before you replace an expensive O2 sensor, (In this case it is actually the A/F sensor) make sure you don't actually HAVE a lean condition. If you have a scan tool, or an Ultragauge, monitor your bank 1 sensor 1 data. While monitoring it, disconnect one of the vacuum lines that is located AFTER the throttle body. Do NOT plug the port. Watch the data to see if it indicates a larger switch to lean. If it does, then reconnect the line and inspect ALL lines and gaskets for vacuum leaks. If none are found, THEN you can look at replacing the sensor. It is a free and easy inspection that could save you from spending $150 - $200 in parts if your problem is actually a vacuum leak.

 

Thanks for all the suggestions. I'll look for vacuum leaks first.