I discovered that my Lexus RX 300 was consuming so much fuel, I mean, I was getting between 7.5 - 8.5 mpg instead of the manufacturer's specified 18-20 mpg so I went to Ladipo and was referred to mechanic who told me the engine and emission are in good working condition and will not need to be tampered with. I was advised to service the nuxxle and injector at Mobil filling station, Gbagada and it cost me 5k to do that there. When I discovered that there was no improvement, I did what I should have done earlier and the result shows, P1155 Air/Fuel sensor Heater Malfunction, Bank 2 Sensor 1.

The mechanic who scanned this told me I have to change the catalist.

Can someone pls interpret this for me.
Thanks.

There are a number of OBD-II trouble codes that refer to either Bank 1 or Bank 2. There are conflicting messages on Bank 1 versus Bank 2, so we're trying to set the record straight.
Quite simply, Bank 1 refers to the side of the engine that has the #1 cylinder. Bank 2 is the opposite side of the engine.
It's not correct to simply state that driver's side is always cylinder #1 or vice versa. Even on cars with a tranverse mounted engine, bank #1 is referring to downstream from the side of the engine with cylinder #1.
Bank 1 is always the cylinder head with the #1 spark plug wire or #1 cylinder.
Bank 2 is always the cylinder head with the #2 spark plug wire or #2 cylinder.
Sensor 1 is before the converter.
Sensor 2 is after the converter.

Bank 1 sensor 2 is after the catalytic converter. On any vehicle, bank is the side of the engine, bank 1 is the side of the engine with cyl 1. Sensor 1 (whether its bank 1 or bank 2) will always be before cat, sensor 2 (whether bank 1 or bank 2) will always be after (in some case, actually IN the cat) cat. Also, on most newer vehicles, sensor 1 is also referred to as heated O2 or air/fuel ratio sensor
From the above I guess you should be able to identify the sensor that requires to be changed. It's the sensor on bank 2 just before the catalytic converter. It's the sensor that needs to be changed not the catalytic converter.

ahh, just seeing this...already replied in the other thread

@Costee,
Thanks. A very detailed instruction.
But how do I know if the catalytic converter is bad?

@NissParts,
Thanks for your response too. You mentioned that the faulty sensor is not supposed to impact on the fuel consumption. Does that mean that the catalytic converter is bad, or is there something else the diagnostic tool is not telling us?

My advise, if your only option for replacement catalyst is a tokunbo then I strongly advise you just remove the catalyst which is blocked and then do what is called an oxygen sensor extender mod (google it).
If you do not do the mod, you will get catalyst codes but your mileage will improve. The mod will ensure you get the best mileage possible with our fuel grade.
You will only need to change the oxygen sensor if you confirm it has a bad electrical connection

nissparts: My advise, if your only option for replacement catalyst is a tokunbo then I strongly advise you just remove the catalyst which is blocked and then do what is called an oxygen sensor extender mod (google it).
If you do not do the mod, you will get catalyst codes but your mileage will improve. The mod will ensure you get the best mileage possible with our fuel grade.
You will only need to change the oxygen sensor if you confirm it has a bad electrical connection

The procedure sounds too technical to me. Been doing some research but it seems its something I won't be able to handle on my own. I'll appreciate if you could be kind enough to recommend a good mechanic that can do the 02 sensor mod for me. Thanks once again for your time.

Give me a call tomorrow. My number is on my signature.
I have a workshop in Yaba

nissparts: Give me a call tomorrow. My number is on my signature.
I have a workshop in Yaba

Ok. Will call u 2moro.