netlander

My 20 year old, 250k miles car, 2003 Lexus ES300 starting to have this problem. Error code P2196 and P0174. Mechanic at shop cleaned throttle body and install MAF. Drive is much smoother, but after couple of days I see PENDING P2196 and PENDING P0174 again. Any suggestion?

Arsenii

Hello,

Which MAF sensor did you end up using?

P2196 - O2 Sensor Signal Biased/Stuck Rich (Bank 1 Sensor 1)
P0174 - System Too Lean (Bank 2)

Not sure why the mechanic went to the MAF sensor first, the codes indicate that you have problems with A/F sensor in the Back of the Engine, towards the Firewall, to verify that it is bad, you will have to look at Engine Live Data, A/F sensor readout.

As for Lean code, I would only look at it after diagnosing P2196, as there is a slim chance that it could be causing a lean condition as well. Check Fuel Trims for both banks and post them here, they should be as close to 0 as possible, anything above 10% is a cause of concern. Considering that it's only one bank that's lean, there is not a lot that could be causing it, like a Bank 2 A/F sensor, Injectors, or the VVT system not reaching its full limits, but it's hard to tell at the moment.

Hope this helps and best of luck!