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Bank 2 Sensor 2 Is300


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Hi guys.

My IS300 is giving the code P0156 O2 sensor, Bank 2 Sensor 2

This is the sensor after the CAT right? Also this sensor was changed just 11 months ago. New sensor gone bad already or something else causing the sensor to go bad?

Many thanks

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Yeah got a 300. I'll put pics up a bit later :)

It's in good condition, 70k, FSH all Lexus except the last. This other garage also changed the sensor so i'm not ruling out they've damaged wires etc..... Previous owner says he replaced this sensor last January, 6000 miles ago with a denso OEM after he had the exact same code. I have the receipts to prove what he says his true.

Very annoying on what otherwise seems a good car. Passed the mot last Saturday, no advisories. So it went through emissions ok.

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wonder if it's something to do with database hiccup other day?

Just checked and time is correct on this post...

Edited by IHgs300
time check
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Yes mate but I'm not really bothered about that right now. Knowing what is causing it is my primary concern. I was just hoping somebody had the same problem with a recurring sensor code and it was maybe a known fault but yeah I'll get a new sensor under warranty if I have to I'm just not convinced the sensor is bad.

Now this is interesting....

On Thursday I checked the coolant as I could hear a rushing water sound behind the dashboard when I started the car and went around corners, there wasn't any! Expansion tank completely dry! So I filled the system with pink coolant and burped it by running it for Half an hour with the radiator cap open. There were loads of air bubbles! I also checked all other fluids and they were fine.

So after doing this I re set the eml codes as the light had come on yet again, same code on the way to work, had it twice in 2 days by now. It's now Saturday night, I've done 128 miles and the light has not come back on. I plugged the code reader in to see if it had stored a code without triggering the eml, nothing, no error codes.

It'll prob come back on tomorrow now that I've wrote this :lol:

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I'd probably have a quick nose at the wiring to the sensor, as that one is quite exposed underneath the car. It's nothing to worry about day to day though, as they are only used for checking that the cat is working correctly, so don't directly effect fueling normally.

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I'd probably have a quick nose at the wiring to the sensor, as that one is quite exposed underneath the car. It's nothing to worry about day to day though, as they are only used for checking that the cat is working correctly, so don't directly effect fueling normally.

Ahh now see I've read differently. I've done a hell of a lot of research on this lol....

They do affect fuelling just not as much as the sensors before the cat. If this sensor detects too much oxygen in the exhaust gases it'll tell the ecu to dump more fuel in and if it detects too much un burnt fuel in the exhaust it'll tell the ecu to put less fuel in.

The eml still hasn't illuminated and I'm up to 200 miles now since it last came on and yet again no fault codes stored.

My theory is this :-

no/low coolant so no temp(can't measure air temp in coolant area), so it thinks the engine cold so over fuels, causing the car to run rich, the O2 sensor picks this up and throws the code.

Or the exhaust gasses were so hot as the car had no coolant that it overheated the sensor causing the code??

Guess it's a waiting game for a bit to see if the light cones back on. It just seems very strange to me that it was going off every 10-20 miles but since I did the coolant it's been good for 200!

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Yeah it's been parked for nearly 4 months mate. Expansion tank had evaporated. Since sorting the coolant out it hasn't lost a drop so doesn't look like a leak. It's still say on MAX.

Strange because I had the exact same coolant prob with the 200 when I bought it. That had been sat a few months also and had no coolant in the expansion tank, but I noticed that straight away and topped it up.

Seems to be a common feature on the IS that the coolant evaporates! Dean (Dinho) had a dry expansion tank at the Gaydon meet earlier this, and also Pete (petayV8) had the same prob with his too. I've also read a lot of threads on here and other forums about low coolant in these cars!

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My header tank is always low doesnt leak, the rad never gets low. Your sensor could have been pickign up a bad burn from the car being stood for a few months fuel goes off with time being the post cat one could have been pickign up small faults with the cat. if its of then dont worry about it.

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