Jadedpanth

Just so I'm clear on all this lingo...a 99 rx300 should have 3 O2 sensors, 2 a/f sensors, and 1 mass air flow sensor...is that right? I feel like I need to take an auto maintenance class. I'm just so tired of getting taken for a ride by these auto repair shops.

Lexmex

Almost.

Two A/F sensors, 1 O2 sensor and 1 MAF.

Let me show some photos.

Lexmex

Bank 2 Sensor 1 A/F sensor. Visible when you open up the hood right on the front of the engine block.

Lexmex

Bank 1, Sensor 1 A/F sensor Visible behind the engine block.

Lexmex

O2 sensor. Located just after the catalytic converter below the vehicle.

Lexmex

Finally, the MAF sensor. The difference here is that I have a different kind of air intake, but I use the same exact sensor. You will find it located just to the left of the big black airbox on the right side of the engine bay.

Jadedpanth

So I guess I'm confused then. My bf replaced an O2 sensor under the hood, not next to the c. converter. Are the O2 sensor and A/F sensor the same part under the hood? And if so, what's with the terminology differences?

Lexmex

They can be called that on certain vehicles, but technically on the RX300, the A/F sensor is actually a different design than the O2 sensor, and the 2 A/F sensors due a different job than the O2 sensor by the converter.

I think what he must have replaced is an A/F sensor.

Jadedpanth

So according to the guy from the japanese auto place, it's entirely possible that I put an O2 sensor in where a a/f sensor is supposed to be...but I mean, the book that we bought told me that was what I was supposed to do. I'm so confused now.

lexus114

Its quite possible that is exactly what happened. And it will not perform like that. An 02 sensor will not take the place of an a/f sensor. (although it will fit in their)

Jadedpanth

This is ridiculous. I mean...why would they even sell front O2 sensors for my vehicle if there arent any?

::edit::

Firestone called me and said that regardless of what lexus calls them, they are still considered O2 sensors (he said there was a little A/F in parenthesis). So I'm hoping that means we only need to change one of them. This whole thing is giving me a freaking headache. I just want a trustworthy person to look at my car and be honest with me.

Lexmex

The codes you showed me earlier don't indicate that would be the issue. I think it's the ignition coils. The P0171 and the P0125 sometimes show up misfires (and they also do with A/F sensor codes). However, none of the codes you showed me winds up being a true A/F sensor issue, say like P1133 or P1135, you don't have any of those. So I'd focus on the ignition coils, see what brand they are.

code58

Jade- Listen to Lexmex- he's trying to steer you in the right direction. When he asks a question it's always for a reason- take it from someone who lives in that world. LOL Step back, take a deep breath and do as he says. His advice is free and my bet is it's probably better than any you've gotten so far. Good Luck!

lexus114

^^^^^I second that^^^^^ Lexmex is a true friend here,

Jadedpanth

I appreciate all of your help. I'm sorry if you feel like I'm not listening to your advice...I am. I just don't understand how people that are physically looking at my car can't know what's wrong with it. It seems like you all know more from just some standard codes than they do.

We were driving home from a New Year's party this morning and my check engine light starts flashing. There's also a burning smell and my car is shaking. This is exactly what happened the last time before my coils needed to be replaced. You better believe Midas is fixing this mess. What exactly can you do to check and see if there is a coil issue?