Wallyrx300

I'm at my wits end. I've had this at the dealer for three days. I've replaced the intake gasket, plugs
, Mass air flow sensor and the engine temp sensor. Still getting these codes. The dealer likes taking my money and is still not sure. Any one know what to do? 2002 Lexus rx300. 129900 on the clock. Please help.

carguy07

B1S1 air/fuel sensor. The dealer couldn't figure that out??

Wallyrx300

Im at a loss. I think they are just running the blll up.

carguy07

I would say they are, that's an easy one.

salimshah

The fix is not a simple fix. I am not trying to disparage carguy's opinion, just saying at times it can be complex.
If it is a bad sensor ... swap takes care of it ...[most on the forum would like to see it that way].
If there is introduction of air in the closed loop .. things can become complicated as the ECU keeps compensating. At this time you really need a savvy tech, who in my mind needs to run an open loop test and take the readings from sensor and then diagnose potential source and then address it.

There is video on the net where a guy explains some of it one white board.

I guess it is time to ask the dealership to assign a master tech.

Salim

Wallyrx300

replaced the o2 sensor twice with original denso parts just incase one was bad out of the box.. Still throwing the code.

carguy07

The A/F sensor in bank 1 has been replaced right? Not the bank 2 O2 sensor?

Wallyrx300

Along with the intake, plugs, vacuum checked, exhaust leak fixed and maf sensor changed
.

Nad1370

Well, they (mechanic, an able one) better start checking wiring or possibly a bad ECU.
Assuming they already checked the correct voltage outputs of the AF sensor.
It should stable at 3.3 V at idle.
During fuel enrichment, using a scan tool, there is a case that the output voltage of the A/F sensor is below 2.8 V
The other (working bank) should also be a reference on the change.

Wallyrx300

so i replaced the ebay denso o2 senosrs with ngk.As it was throwing the codes for that. it took care of everything for 1 day. i hit the gas hard and then the vsc light and check engine light is on. not it onlyhas a code for bank 2 lean. Any help here?

Nad1370

Wallyrx300

its not throwing a code for the o2 sensors any longer. now its jut the bank 2 lean.

Nad1370

Without looking at your fuel trims or AF voltage at idle, i cant say for sure what that LEAN code maybe. (P0171 im assuming).
Granted you dont have any exhaust leaks in that bank.
But usually when this code pops up, its more than likely a bad reading AF sensor.
Just for future reference:
O2 sensors are different that AF sensors.
O2 sensors are located after the cat.
AF sensors are located before the cat.

carguy07

Those two words in the same sentence is concerning. Was it a reputable seller?

Wallyrx300

i guess not.