trips1

Thanks to everyone on this forum for all the detailed information on AF/O2 sensors. I want to be certain about the AF sensor before placing an online order. So please pardon me for any repeat questions.

Please can someone help me with the following.

- There are 2 identical AF sensors. A pair of either one of the following should work on RX300, 2001, 2WD.

http://www.factorylexusparts.com/ser...IR-FUEL/Detail

http://www.amazon.com/Toyota-Highlan...9738785&sr=1-3

http://www.amazon.com/Denso-234-9009...3794019&sr=8-1


- Are both these AF sensors located near to each other? Can both of them be reached from the top of the Engine?

- I am thinking of using the following DIY. A pointer to indicate the second AF would be helpful

https://www.clublexus.com/forums/rx-...el-sensor.html


Some background:
My CEL came up and the error codes reported at an independent mechanic shop are P1130 and P1150. So it looks that my AF sensors have gone bad. Few months ago even without the CEL i had got another independent mechanic to run diagnostic on O2/AF sensors because of my very low MPG (14-15) and he had reported weak/bad AF sensors.

code58

Trips- To answer your 1st question- no, the sensors are not located near each other. The front 1 is real easy to get to. When you lift your hood, it's right in front on the exhaust manifold. You've seen the pictures in the listings you posted so you know what it looks like. The other 1 is on the back exhaust facing the firewall and for that 1 you have to jack the car up, put it on stands and get it from under the car. The difficult part is releasing the plug. There are postings on the Lexus forums from people who have figured how to do it without too much difficulty. Search feature is your friend. There are many of these posts that have good pictures of exactly what to look for. You have the correct sensor in all 3 of the sources, so I would just go for the cheapest of those. The Denso is the correct sensor and even though they make it for Toyota, the part # belongs to Toyota so they have to sell it under their own part #. Same sensor.

trips1

Thanks for your reply code58.
So both the AF sensors are same i.e. Denso 234-9009.

I got the codes as P1150 and P1130. Though the mechanic mentioned that only bank1/sensor1 may be bad, is it advisable to get both of them changed together? My MPG has gone down by 2-3 miles in last 6-7 months.

Also can someone help me complete/correct the terminology here:

(A)Bank1 Sensor1 --- Is it the one near the front of the exhaust manifold and easy to change?

(B)Bank1 Sensor2 --- Is it the one near the firewall and difficult to change?

(C)Bank2 Sensor1 (If this is the correct name ) -- Is this the O2 sensor and only affects emission.

(D)Bank2 Sensor2 -- Nothing like this exists.

Thanks a lot to everyone in advance.
Trips

Lexmex

A little off.

Give me a second, and I'll show some posts/photos on each.

Lexmex

Bank 2, Sensor 1 (readily visible in your engine bay behind radiator area and coming off the front of the engine block).

Lexmex

Bank 1 Sensor 1 (behind the engine block and you have to crawl underneath to see it).

Lexmex

Bank 1, Sensor 2 (underneath your vehicle and behind the main catalytic converter) (yep, this is the emissions one).

Lexmex

When that day comes to change one of my a/f sensors, I'll change both, but I checked both out with my OBD2 scanner (one of the recent threads has some pictures of the readings from my laptop), and they check out okay despite the years in Mexico. It's your call on this one, but given the economy I'd opt for just replacing the bad one right now.

trips1

Thanks for all the useful info.

One more question. After erasing the CEL codes (P1130 and P1150) from the code scanner i don't see the CEL again. Please note that my battery was bad too and i replaced it 2 days ago. I have already driven about 40-50 miles and CEL has not come up again so far.

So my questions is does it harm the engine/car in any way to drive it with weak or broken AF sensor?? I wanted to drive more and see if the CEL comes up again before investing couple of hundred dollars on the AF sensors.

Thanks.
Trips.

Lexmex

Well if you do indeed have a bad a/f sensor, you're going to get worse mpg, in the short run, it's not going to do any other real harm. Yeah, keep driving it until you see it pop up. I've had my fair share of a/f sensor issues, but still riding the original sensors you saw above in the photos and recent readings of the sensors via laptop software bare it out they are running okay.

blaster30

Are both of the O2 Sensors the same? Should I order 2.

http://www.rockauto.com/catalog/raframecatalog.php?ck[viewcurrency]=USD&ck[ID]=0&ck[idlist]=0

carguy07

Both Air Fuel Sensors are the same. I would only replace with OE/Denso (amazon is usually the cheapest). I know that dealers tend to replace them in pairs. If it's my money, I would just replace the faulty one and wait to see how the other one does.

busidit

Not sure if this thread is still alive but I am preparing to install a new Bank1 Sensor 1 along with a new bank 1 cat. The cat is leaking and sensor is giving me a P1135 code in addition to P0171 and P0125.

I am concerned about the new AF sensor I got on Amazon. Out of the box I tested the resistance across the heater circuit and found 15 (fifteen) ohms. This worries me being so far off spec.

Any thoughts?

salimshah

Is it OEM? Dont waste time and money on anything else.

Salim

lexus114

Also, (as odd as this may sound) you will get the longest life outta those sensors on premium or mid grade fuel.