RX in NC
You are very knowledgable on this RX300 subject. I had the CEL on my wife's 99 RX300 (84k miles), Autozone read code P0171 (System too lean Bank 1), other discussion pointed me to the Air Fuel ratio sensor. I learned that bank 1 sensor is the one closer to the firewall. I could loosen the mine, fearing breakage I brought it to the local shop (Honest Engine) to have them remove it. They didn't do anyhting special other than forced it out, part of the thread came with the sensor and they made me pay for it claiming that Lexus must have crossed treaded putting it in. So I was out over $1100 for the manifold, gasket, sensor and labor. AND now I still have the same error. Unbelievable !
Can you please tell me which sensor the dealer replaced on your wife's car ? Bank 1 (near firewall) or bank 2 (near radiator). I will never to back to Honest Engine again and cannot afford to feed the dealer at this point. Did you ever clean the Mass Air Flow sensor ? How did you do that ?
(I will not buy another RX either)
Thanks
APN