2001 Lexus RX300 Q&A
2001 Lexus RX300 Question: 2001 rx300 cel codes P0171 P0174 P1150
The worst bank will set the code first. I also find that cleaning the Mass Air Sensor to be ineffective, especially the type that a Lexus uses, which is based on the newer Bosch thin film Air Flow Sensor. About the only area that you can clean is the intake air sensor which does nothing to help you. Refer to this article below that I wrote about how to inspect for a code P0171 and/or P0174. You must be able top SEE the Long Term Fuel Trim on the scan data, so if you are trying to diagnose this code with out any scan data, you will have a really tough time. The Long Term Fuel Trim is typically above 12 % for the code setting bank and the other bank may be close, but still under the code setting level, like 10% etc. A code P0171 has NOTHING TO DO WITH a defective air fuel ratio sensor!!!! or a defective oxygen Sensor, they have to be passing their self tests to even set this code, this is a huge misconception most shops and Techs have. So follow this article -> http://repairpal.com/OBD-II-Code-P0171-and-P0174 look for any vacuum leaks and then find find the long term fuel trim, if both banks are high ( like over 10-12% ) and pretty even, then the air flow sensor is suspect, IF you don't have vacuum leaks. Also if the air cleaner is pretty dirty or if the air box for the air cleaner is pretty dusty, that will wipe out the air flow sensor, because the dust sticks to and ruins the thin film sensor. I recommend cleaning the air cleaner box and replacing the air cleaner every 12 mos or 12k miles, minimum. It saves your Mass Air flow Sensor big time. - dandd
can anyone recommend a low priced decent scanner and where to purchase? i need one to correctly diagnose codes P0171 P0174 bank 1 bank 2 syst too lean, P1150 AF sensor range perf bank 2 sensor 1. ...
The Check Engine Light may illuminate because the mass air flow sensor sends incorrect information to the engine control computer. This can cause a loss of power on acceleration. A failed mass air ...