My car is having trouble passing emissions in TX. I could use some guidance from the collective wisdom here.... Most recent inspecting report from this past week indicates a well running car minus a failure at high speed test for NOx. Prior to this test I have replaced (all since april) plugs, wires, cap/rotor. All oem spec parts from O'reillys, no performance parts. I recently installed new flowmaster 2.5" mini cats as well. maybe 150mi on the cats. Using a friends Matco Monitor 4000 Enhanced scanner, I retrieved the following codes last night after driving home approx 30mi hwy in 107+ temp. KOEO 564- Fan control circuit failure KOEO ( I do hear both fan speeds come on during the test though...) 181- Fuel system at rich adaptive limit at part throttle, system lean B1 186- Injector pulse width higher than expected (with BARO sensor) (BARO=barametric psi?) 189- Fuel system at rich adaptive limit part throttle, system lean B2 KOER-PASS and Cylinder Balance Test PASS After some google fueld semi professional amateur guestadiagnostics, I replace my O2 sensors with NTK sensors as a place to start. Drove home tonight, same mileage, approx 90* temp and pulled the following codes. KOEO 564 2x SEPARATOR 10 Keep alive memory codes 181 2x I then ran the fast codes option on the scanner and came up no codes. Re ran the slow code option and got a KAM codes PASS...which I thought was strange... KOER codes were 172- Lack of heated Oxygen Sensor (HO2s-1) switches, indicates lean B1 136- Lack of heated Oxygen Senosr (HO2s-2) switch during KOER, indicates lean B2 CBT PASS I will clear the codes in the morning and go drive the car since I have not cleared the codes since installing the O2 sensors. I know high NOx is caused by high combustion cylinder temps, and I clearly have a lean eng condition, but I'm not sure how to correctly identify the exact cause.