New guy here... please direct me to another thread if this topic already exists, I looked but couldn't find one.

So, codes for a faulty bank 1 front O2 sensor and bank 1 running lean. I changed the sensor and cleared the codes, advisory light comes back on again with same codes. I checked the vacuum lines with no obvious breaks. I think the SAI pump didn't come on the last couple times it started. Could this be the source of the problem? What other things should I check?

Thanks for the help.

 

I had a similar issue (had more codes involving both sides, including cat damage code) which was apparently caused by an exhaust leak on both the left and right manifold to downpipe connection.

 

start looking for an exhaust leak.......check the manifold against the block, if your exhaust has ever had any work, check the welds,clamps,flanges, etc. also recheck your vacuum connections. and report back with your findings

 

What are the exact fault code numbers you are getting?

 

I had this code, I replaced the # 1 o2 sensor, on the driver side closest to the manifold, if you dont have any exhaust leaks it should be that.

 

If I remember correctly P0130 and P0171. I've never had any exhaust work done but I will check for a leak. One of the bolts connecting the exhaust to the manifold is sheared off, that may be part of the problem. I'll check and let you all know.

 

I do have an exhaust leak on the left side. But the SAI pump is not coming on. In the past, it comes on after the engine has sat for even just a couple of hours. It's been sitting for about a week and the pump didn't come on. Could this be part of the problem?

 

The SAI should be cause a leak unless the lines are broken. The fact that it doesn't come on, along, wouldn't result in a lean code. An exhaust leak would, however.