I recently got a CEL and I found out it is a P0171 code. I cleaned out the MAF and the code cleared for a while but came back again. Then it will go off by itself and now, it is back on.

At this point, I am suspecting the O2 sensor is bad. Does anyone have pics of where the O2 is located?

Thanks a lot in advance.

 

Go to www.obd-codes.com Great site and a ton of info there. Go to the Lexus part and you can look at a bunch of posts for different trouble codes and what the probable cause and cure is. I would do more research before I started throwing parts at it. Too many people throw parts at a problem and then their wallet is just thinner and they still have the problem. That site can definitely give you some help. Good Luck! Roger

 

This is a widely discussed issue on this forum.

O2 sensor is after the main catalytic converter below. There are also two A/F (air/fuel sensors) off of each manifold. You can see one just in front of the engine block on the exhaust manifold leading out. The problem is that if one of these sensors is bad, then there are codes that should follow the P0171, not just the P0171 by itself. Additionally, a lot of mechanics (doesn't need to be Lexus) have advanced OBD2 scanners that can read the readings from both A/F sensors to see if there is an issue.

Another cause of a P0171 is a crack on the exhaust pipe. You might want to check underneath the engine block as there is an exhaust piece there, an accordion-like junction, that can break. Additional areas can be the air intake (any of the hoses leading to the air box being loose or cracked). Fuel injectors might be dirty and need cleaning (I recommend Redline's Fuel System Cleaner- Pep Boys should have this). Engine coolant temperature is a remote possibility.

Another one that you should check is the IACV valve, https://www.clublexus.com/forums/sho...d.php?t=358579

 

i agree with lex as he has helped me many times do the sticky first most likely its just the iacv valve that needs to be cleaned i have done this many times and wont see it again, they get dirty, look in begining thread about gas mileage lexmex shows step by step ceaning procedures that can save you alot of money..... try it first, i get p0171 just by climate change or climbing altitutde at times for example travel to beach air gets cooler then traveling to next city 10 degrees warmer then p0171 comes up do to climate changing in another city all of a sudden... hope that helps p0171 and p0174 are common codes to most rx300, and luckily hopefully nothing else as it can get expensive.... ask lex helped me every step of the way...