The car had started idleing rough while in traffic before the CEL came on. I had the codes pulled at Advanced and this is what they were:
P0174 System Too Lean - Bank No. 2
P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1.
Because both of them indicate a lean condition I started checking for Vacuum leaks and Cleaned the MAF. I did not find any broken hosed or tubing but I did figure out that my upper intake manifold bolts were LESS that finger tight. So I pulled the whole UIM off to make sure that the gaskets were still good and to make sure the LIM bolts were torque to specs. I did not pull the IAC to clean it but I did confirm that the EGR passages were clear. After resetting the computer I drove the car about 5-10 minutes before the CEL came back on. I have not had them checked again to see if they are the same codes. My questions are
1. Should I still replace the Bank 1 Upper O2 sensor? (That does not explain the 0174 code)
2. Could the codes be residual from before I tightened the UIM bolts, and I need to go through the 5-6 driving cycles before the codes go away.
About a month ago I have a FMS 9mm #4 Plug wire go bad when I tired to start the car. I have replaced the wires and plugs, could these be a result of the bad wire?
