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Discussion Starter #1
Hello all,
I’m new to RAV4world, so please forgive any errors. I have a 2007 RAV4 V6 with 147k miles. Recently the engine, VSC, and TCS warning lights came on and the codes P2195 (S1B1 lean) and P0138 (S1B2 high) came up. I purchased two new sensors (Not denso, probably the culprit) and replaced the bad ones. I cleared the codes and took it for a drive. Lights came on again and the code P2196 (S1B 1 rich) came up. Evidently S1B2 is working fine now, but I can’t figure out why S1B1 would be lean and then rich. Unless the sensor is bad. I appreciate any expertise or advice. Thanks in advance.
 

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hi and welcome to the forum

The codes are set because the air/fuel ratio is not as the ECU expects. I hope you have kept the original sensors - I will try to explain why. The warning lights have probably come on because of the engine "issues" - for now, do not go after those. If you go for sensors, I would stick with OEM or OE brands.

S1B1 lean can be set if there is more air getting into the system after the mass air flow sensor, or not enough fuel delivered by the fuel system. or an air metering issue. It may be a sensor issue, but the likely hood of both sensors going wrong at the same time is very slim. I would look at fuel trims if you are able by using an OBD2 scanner - if you do not have one, a reasonably cheap one that shows fuel trims can be purchased for around £40 here in the UK - I am sure there is similar over there in the USA.

S1B1 rich can be set by faulty fuel pressure regulators, leaky injectors or wrong fuel type (not suggesting that you have used the wrong fuel BTW).

All of the above could be caused by a wiring signal issue or a faulty PCM etc.

If you are able to search gearsmagazine.com an article on making fuel trims work for you may give an insight into the fuel trim issues you see at the moment and give direction.

Another question - is your RAV a 4 cylinder or 6 cylinder. The reason I ask is there are 2 banks on the 6, so as you are showing just one bank issues, that could be a fuel delivery issue to just that bank (eg injector sticking) or an intake or exhaust gasket leaking on just that bank.

Sorry for the lengthy reply. I know it has not answered your question, but it may give you direction :)
 

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When you get P0136/P0138 (B1/S2) it is really the B1/S1. You should have researched this before doing anything. It is well documented in the forum.
 

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Discussion Starter #4 (Edited)
hi and welcome to the forum

The codes are set because the air/fuel ratio is not as the ECU expects. I hope you have kept the original sensors - I will try to explain why. The warning lights have probably come on because of the engine "issues" - for now, do not go after those. If you go for sensors, I would stick with OEM or OE brands.

S1B1 lean can be set if there is more air getting into the system after the mass air flow sensor, or not enough fuel delivered by the fuel system. or an air metering issue. It may be a sensor issue, but the likely hood of both sensors going wrong at the same time is very slim. I would look at fuel trims if you are able by using an OBD2 scanner - if you do not have one, a reasonably cheap one that shows fuel trims can be purchased for around £40 here in the UK - I am sure there is similar over there in the USA.

S1B1 rich can be set by faulty fuel pressure regulators, leaky injectors or wrong fuel type (not suggesting that you have used the wrong fuel BTW).

All of the above could be caused by a wiring signal issue or a faulty PCM etc.

If you are able to search gearsmagazine.com an article on making fuel trims work for you may give an insight into the fuel trim issues you see at the moment and give direction.

Another question - is your RAV a 4 cylinder or 6 cylinder. The reason I ask is there are 2 banks on the 6, so as you are showing just one bank issues, that could be a fuel delivery issue to just that bank (eg injector sticking) or an intake or exhaust gasket leaking on just that bank.

Sorry for the lengthy reply. I know it has not answered your question, but it may give you direction :)
Thank you for the info Bigphill555. My RAV4 is a V6 and has 147,000 miles.

the codes I’m getting are only on bank 1 side. I do still have the old sensors. But S1B2 issues haven’t returned since I installed the new sensor, so I figured that one really was bad.

I’ll hook up my scanner and look for injector issues, look for gasket leaks and run a fuel cleaner through it to see if that helps.

FYI, on my test drive I didn’t notice any engine or power issues. The acceleration felt normal and ran smooth on the city streets and the highway.
 

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Discussion Starter #5
When you get P0136/P0138 (B1/S2) it is really the B1/S1. You should have researched this before doing anything. It is well documented in the forum.
thanks for the reply DL175. my original codes were P0138 and P2195 (stuck lean). I did replace S1B1 and now it’s reading P2196(stuck rich) after the replacement.
 

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Thank you for the info Bigphill555. My RAV4 is a V6 and has 147,000 miles.

the codes I’m getting are only on bank 1 side. I do still have the old sensors. But S1B2 issues haven’t returned since I installed the new sensor, so I figured that one really was bad.

I’ll hook up my scanner and look for injector issues, look for gasket leaks and run a fuel cleaner through it to see if that helps.

FYI, on my test drive I didn’t notice any engine or power issues. The acceleration felt normal and ran smooth on the city streets and the highway.
DannyN , you are welcome, and I hope you find the cause.

As it is a V6, and on B1 only, is is possible that it is a faulty sensor, and as it has not come back, you are probably heading in the right direction. P0138 is set by the sensor detecting rich (ie above 900mV) for, I think, more that 10 seconds. Fingers crossed.

Being a V6 and two bank, it rules out a faulty engine and coolant temperature sensor sending incorrect info to the PCM as this would show on both banks.

P2196 indicates that B1S1 is running full rich (again over I think 10 seconds). This maybe a faulty (new) sensor, damage to the wiring on that circuit, or yes, running rich on B1 (maybe leaky injector). Maybe try putting your old B1S1 sensor back in, and recheck for codes?? It may give you a direction then if you get the same, or different results

Let us know what you find :)
 

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Discussion Starter #9
DannyN , you are welcome, and I hope you find the cause.

As it is a V6, and on B1 only, is is possible that it is a faulty sensor, and as it has not come back, you are probably heading in the right direction. P0138 is set by the sensor detecting rich (ie above 900mV) for, I think, more that 10 seconds. Fingers crossed.

Being a V6 and two bank, it rules out a faulty engine and coolant temperature sensor sending incorrect info to the PCM as this would show on both banks.

P2196 indicates that B1S1 is running full rich (again over I think 10 seconds). This maybe a faulty (new) sensor, damage to the wiring on that circuit, or yes, running rich on B1 (maybe leaky injector). Maybe try putting your old B1S1 sensor back in, and recheck for codes?? It may give you a direction then if you get the same, or different results

Let us know what you find :)
thanks again for the info. I agree. I’m thinking about throwing the old Sensor back in and seeing what happens. I’m interested to see if it goes back lean P2195 or stays rich P2196.
 

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It is best to chose Denso or even NGK for O2 sensors so you don't have unnecessary problems.
 

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Discussion Starter #11
Update: the new aftermarket B1S1 sensor I installed was bad. I threw a denso sensor, I knew was good, in and It’s been running great, no warning lights. Thanks everyone for the info and suggestions.
 

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Update: the new aftermarket B1S1 sensor I installed was bad. I threw a denso sensor, I knew was good, in and It’s been running great, no warning lights. Thanks everyone for the info and suggestions.
Glad it is sorted, and you have one smooth running Rav - thanks for the update
 
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