# 2005 toyota sienna repair problems-help



## shirbon (Oct 2, 2014)

I have a 2005 sienna XLE V-6 3.3 L, check engine light, SCV light and TRAC light all on at same time. scan says P0051 HO2S Heater Control Circuit Low ( Bank 2, Sensor 1 ). I gather that is one of the oxygen sensors before the converter. My question is what side of engine is cylinder number one on, is bank 2 opposite side on number one cylinder or same side, would that be closest to front of van or closest to fire wall ? I seem to get conflicting info when I try to research it. I don't want to buy the wrong sensor as I see there not cheap. any pics would be great also. thanks


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## Windows on Wash (Aug 30, 2011)




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## Brainbucket (Mar 30, 2015)

Firing Order 




Motor Abbreviation Definitions
Firing Order 
1-2-3-4-5-6








The sensor Bank 2 sensor 1 is the bank closest to the front of the vehicle and the sensor is before the cat.:vs_cool:


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## shirbon (Oct 2, 2014)

thanks Brainbucket, that's what I thought but wanted to be sure. Do you know if the same sensor would be use for bank 1 and bank 2 as long as they are both upstream sensors ?, that's another problem I am having all the parts places seem to have one listed as bank 1 and nothing for bank 2. I think Windows on Wash sent a pic or video that I cant seem to view.


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## Brainbucket (Mar 30, 2015)

The only way for me is to compare part numbers.:vs_cool:


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## shirbon (Oct 2, 2014)

ok, I ordered a new sensor online from autopartswarehouse. It came yesterday, I installed it, started it up and cleared the codes, everything is fine no warning lights are on anymore. drove a couple places across town and driving home all the warning lights came on again. frustrating. Not sure if its because the part is a cheaper after market or if there is some other problem with the vehicle. Any ideas ? Thanks.


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## Brainbucket (Mar 30, 2015)

What are the codes?:vs_worry:


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## shirbon (Oct 2, 2014)

Brainbucket I'm glad you asked. after installing the sensor yesterday and driving it last night I never checked I just assumed it was the same code and the cheap sensor quit already. So I went and checked, its a different code. P0156 o2 Circuit ( Bank 2, Sensor 2 ) stored twice. My original post was P0051 HO2S Heat Control Circuit Low ( Bank 2, Sensor 1 ). that didn't show up before,why do you think replacing the first sensor caused this one to to have trouble code to now and didn't say that before ?, is there some other problem maybe ? How hard is it to get at this one to replace ?


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## Drachenfire (Jun 6, 2017)

This is why it is always good to have Chilton's book on hand...

It is not perfect, but it does provide enough information to do most repairs.


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## KHouse75 (May 14, 2008)

How many miles since you last changed the O2 sensors? It's recommended to replace them all every 100,000 miles. If you haven't replace them all already, it may be a good idea to do so.


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## Brainbucket (Mar 30, 2015)

I don't replace parts until they are broke. When the first sensor went out it prolly contaminated the one down stream. Change it. It's the same side as the 1st sensor but after the cat.:vs_cool:


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## KHouse75 (May 14, 2008)

O2 sensors may not break but they have a finite life and fuel efficiency suffers big time when then are past their recommended lifetime. I went from getting 20 MPG on the highway to 13 MPG over a few years in my Suburban. Installed new O2 sensors and I'm back up to 20 MPG.


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## Brainbucket (Mar 30, 2015)

KHouse75 said:


> O2 sensors may not break but they have a finite life and fuel efficiency suffers big time when then are past their recommended lifetime. I went from getting 20 MPG on the highway to 13 MPG over a few years in my Suburban. Installed new O2 sensors and I'm back up to 20 MPG.


I agree they do fail. But I have seen O2's go 300,000 miles and are still doing ok. But a tech can see that with a good scanner. O2's do not like water. Water or condensation does get into the combustion chamber through fuel mostly but can come through the air. Fuel filters mostly stop water but some does get through. When it gets burned in the combustion chamber, it creates steam and that's kills O2's. Plus the crap they introduce into fuel. Also shock (a violent force not electric) kills them. If you drop an O2, it's dead. I've seen O2's die in a accident because of shock. I just look at the response time an O2 does when I test it. The Scanner tells all.:vs_cool:


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## shirbon (Oct 2, 2014)

ok, I replaced the down stream one finally. cleared the code, drove it a few places around town and on my way home the warning lights came on again. the code is the same P0156 ( twice its stored ) o2 circuit ( Bank 2, Sensor 2 ). now whats the problem ?


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## Brainbucket (Mar 30, 2015)

Where you get the sensor? If someone dropped it, it's dead. Need a scanner to see what's not working. But first check your fuses. The heated part is protected by a fuse. Also, do you have an exhaust leak? The code says it's not switching/working.:vs_cool:


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## shirbon (Oct 2, 2014)

Brainbucket, I got the sensor from autopartswarehouse, same place I got the first one that seems to work ok, could it be the wrong one ? I don't think there is an exhaust leak, could be I guess that we haven't noticed, what would that have to do with it ? would the fuse be under the dash or under the hood ?, wonder what it would be labeled as ?, is there a fuse for each sensor or are they all on the same one ?


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## Brainbucket (Mar 30, 2015)

The EFI 2 10 amp fuse it in the underhood fuse box feeds the O2 heaters in both O2s. It also controls the tranny so I would assume that it's good. If air is being introduced in to the exhaust via a leak, it messes with the O2. I would see if you can swap the O2 position as take the the front one and put it in the down stream and clear codes and drive it to see if the same code comes back or it switches to the front. If it switches, then you have proven it's a bad O2. If not, then we either have a wiring problem or a bad PCM. I see that they have different part numbers so I would think that they can't be swapped but see if they can be plugged in. The connector is what is diffrent. You are going to have to either use a scanner or defect that O2 and get another one.:vs_cool:


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## shirbon (Oct 2, 2014)

I think the plugs are the same.what if there was a leak down stream from the sensor, would that still affect it ? I still wonder if its a bad part or the wrong part though. what does PCM stand for ?, too many acronyms


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## Bigplanz (Apr 10, 2009)

shirbon said:


> I think the plugs are the same.what if there was a leak down stream from the sensor, would that still affect it ? I still wonder if its a bad part or the wrong part though. what does PCM stand for ?, too many acronyms


Powertrain Control Module


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## shirbon (Oct 2, 2014)

do you think the sensor is bad or do you think there is another problem ? autopartswarehouse said they will exchange this one for another one. or do you think it will have the same ol problem again ?


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## Brainbucket (Mar 30, 2015)

The only way to know is to swap it out or put a scanner on it.:vs_cool:


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