Check Engine Light Rx300 P0171

[begvis]

I've been lurking around here for awhile trying to self diagnose a CEL and trac off prob...

It gives code of P0171 Bank one lean, I started with cleaning the MAS with TB cleaner and drying it out..Disconnecting battery for 15 mins to clear CEL.. Car has no power at first but will start to regain its old self after a few miles... I think this is the result of the MAS being cleaned..

The CEL and trac light came on again..

Does this mean that the MAS is garbage get a new one since cleaning it didnt fix it? and to buy a new one for $250 ish? If so what is a good internet store for them?

How do I discern that it is the MAS and not one of the three O2 sensors?

I looked around the bay for loose hoses for a vac. leak but I really dont think that is the prob

Should I buy a new MAF and hope that fixes it or should I go the O2 route first and replace those?

Thanks for the input

99 RX300

126000 miles

2wd

Transmission strong as ever :)

B

[doanh]

Hello,

I got the same problem. I took it to a dealer here in Southfield MI and they told me that the knock sensors along with the MAF is bad.

I cleaned the MAF and the problem came back so I think it is the knock sensor. It is interesting you mentioned O2 sensor..

If you got a response, please share. Thanks in advance.

[spachpande]

I had the same problem. Dealer told me to change the MAF meter. He changed it and it did not fix the problem. I went back to him and he looked into it and said that now the O2 sensor is bad. He changed the O2 sensor and the problem was solved. I don't know that MAF change was really needed.

[doanh]

Interesting... Did the dealer tell you the knock sensor was a problem first?

I am planning on taking the car to Autozone for a error code. The dealer specifically told me the MAF and the Knock Sensor was bad.

It is rare for the MAF to failed at 90k miles on the car. It is rare that this unit fails at all.

Now, I need to know if it is the O2 sensor or the Knock sensor.

[RX in NC]

Don't know why you believe that it is rare for the mass air flow sensor to fail. My experiences with our RX300 (as well as the numerous complaints about failures here on this board) tell me that mass air flow sensor failures on the RX300 series are common. Often, however, the sensor can be cleaned instead of replaced. Do a search using key words "mass air flow sensor cleaning" and you'll see what I mean....