I had a ziner run the codes on my TL and the codes read p0175 and p0172, then said running rich on bank 1 and bank 2. I went to AutoZone and asked the personel what bank 1 and bank 2 was and they said it was my O2 sensors. And if i'm running rich its most likely because they are malfunctioning. Now i got my TL used at 93k and now reaching 105k. When i swapped spark plugs i noticed that nothing really has been done to the car. So does anyone know about how long the O2 sensors are suppose to last? and if it does have potential to make the TL run rich if malfunctioning?

 

there is really no expected life of an o2 sensor...i work @ a lexus dealer and we have had to change em on cars w/ less than 2k miles on em...but yeh it can make ur car run rich...its sending faulty info back to the ecu and the ecu is tryin to compensate for it...so get em changed and you'll be good

 

cool thanks! I'm gonna seafoam this weekend first and see if that will have an affect on it as well. but i'll have to take the replacing of the O2 one step at a time cause the O2 on both banks (one located up front on the engine and the other in the back) both run over $110 a piece!!!!! Oh and a bit of info if you didn't know the 3G TL doesn't have a speed sensor! The odometer is read through the ABS system that connects to a knuckle on the wheel ! Only the RL and MDX have sensors!

 

the bank means which cylinder set- the left side (front) of the engine or the right-rear set.
Thats why I suggested its a false code
Codes are not diagnosis- merely CLUES to the real problem
Having 2 sensors fail is possible but lets start simple before dropping big cash
And for others- you can TEST the O2 sensors- one of our gurus will have the electrical spec for them
Whats you fuel mileage these days PK? mid 20s or high teens? running that rich will suck down gas like its a dollar a gallon!
Remove a spark plug and check its color- if its wet, oily and/or smells like gas---

 

On my gen2- there are 2 O2 sensors- one in front of the catalytic convertor and the other after it- so the computer compares whats going in vs out and adjust the amount of fuel going in the engine.

 

Whatever you do, don't buy o2 sensors yet. The codes you have indicate that they are probably working. O2 voltages go higher as they sense rich running. When they fail it's usually low voltage or slow response time. Have someone who knows what they're doing check it out. Possible causes for rich running[which I think you've got] could be excessive fuel pressure, map sensor, temp sensor, egr valve sticking open, tight valves, retarded cam timing etc. You're due for the t/belt and valve adj. which would eliminate at least 2 areas of concern. I think there's a tsb on the valve adjustment. If not I'd adj the exhaust valves toward the loose end of the specification, as they tend to tighten in use.