O2 SENSOR EXPERTS NEEDED

[Firepower2]

I have the Engine Malfunction Light lit up on the dashboard on my 2007 Hilux Winnebago. My OBD 2 Scan Tool shows this error:
PO138 - Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2)

This is a drawing from the Toyota parts computer which shows two sensors:


I have a idea on which one it is but would just like it confirmed so I do not buy the wrong one, as they cost $330 unless someone can tell me a cheaper place to get them.

This picture shows the error:


This is Page 1 and I suppose everything is all right here:


Page 2 - I suppose everything is all right:


Page 3 - THIS MIGHT BE AN ERROR:


Page 4 - Looks all right?


Page 7 - Looks all right:


There is nothing much on the pages I have missed.

These are photos from ScanTool:


THIS LOOKS LIKE A PROBLEM!


Not sure if this is all right:


I wonder if anyone can advise which sensor to replace from the Toyota Drawing above? It seems simple to me but I might be wrong.

[Firepower2]

Guess I will need to have another go and get the photos to work.

Got them working.

[toyboata]

Have you tried clearing the code and see if after driving it reappears? The fuel trim looks a bit high so it could have just been running too rich and sent the o2 sensor voltage too high. If the code appears again then maybe buy a sensor as probably faulty. It's the second sensor, the one after the catalytic converter. Try Bursons or even better Logicar for a replacement .

[Firepower2]

So it looks like the one with the short wire on the right of the top drawing. That is the one I thought it was and took it out last night and cleaned it in petrol but nothing really came out.

I have reset the code 4 times but it keeps coming on. Apparently it goes rich if the sensor is not working to protect the motor. Apparently you can put them in a flame to remove the oxygen and test them with a multimeter. I am not sure which wires of the four to put the multimeter on.

The picture marked Page 3 above shows zero volts when the first ScanTool picture above says high voltage which seems strange. So a loose wire somewhere or the sensor is broken. More likely to be the sensor broken but at 150,000K I understand it should be changed anyway.

Thanks for your advice.
Col

[toyboata]

Cleaning them in petrol is not a good idea, MAF cleaner would be better. After 150,000km it would be due for a change anyway, only really have a serviceable life of 80,000km. It is the sensor you refer too.
With the sensor plugged in and the engine running check voltage on the black wire and if it's not black it will be blue. Should hover around .5 volts on the post cat sensor I'm pretty sure.

[jap]

Were those fuel trims measured at idle? Was the engine at temperature?

[jakelux]

My engine light has been on for 8 months since i installed aftermarket exhaust and has the same error code. have reset a couple times but think i will have to bite the bullet and get new sensor, i was quoted $290 from toyota so hope it works...

[Firepower2]

Hi jap

Those fuel trims were at idle and the engine would have been on for about 4 minutes.

Too rich? Maybe because the O2 sensor is broken?

[Firepower2]

Hi jakelux

So have you got the same error - PO138 Bank 1 Sensor 2?

I was quoted $330 from Toyota so I suppose you checked the price a while ago. Pity my mechanic mate has retired or I could get it at the right price.

Burstons just quoted me $217 which comes from NGK in Melbourne but I guess I should get a Toyota one.

[Firepower2]

Hi toyboata

I know it is a stupid question but when dealing with the computer I get a bit nervous.

So it is all right to start the engine with the sensor plug out so I can check the voltage on the pins of the sensor?

Apparently the other way is to put the sensor quickly in a portagas flame to remove the oxygen and test the voltage.

[jakelux]

Hi jakelux

So have you got the same error - PO138 Bank 1 Sensor 2?

I was quoted $330 from Toyota so I suppose you checked the price a while ago. Pity my mechanic mate has retired or I could get it at the right price.

Burstons just quoted me $217 which comes from NGK in Melbourne but I guess I should get a Toyota one.

My faults came up with:
P0031 oxy a/f sensor heater control circuit low, bank 1 sensor 1
P0051 oxy a/f sensor heater control circuit low, bank 2 sensor 1
I have part no: 89465 for both oxy sensors left and right (they are the same)

Toyota and others have said there are a lot of issues with the codes coming up after fitting after market exhaust/headers.
From my experience of talking to people about this over the past 8 -10 months there is a lot of contradicting info going around and not a lot of fact in how to fix the problem.

Yeah mate i would stick with the Toyota part personally.

I will be ordering two new oxy sensors when i get back from the bush, so hopefully that fixes my problem if not there is maybe something up with my cataylic converter...

Jake

[Firepower2]

Mine is Bank 1 Sensor 2

Yours are:
Bank 1 Sensor 1
Bank 2 Sensor 1

So that is 3 sensors. I only know two sensors on the exhaust pipe but there might be more some where.

I went to Toyota a while ago and got the drawing as per my first photo (2007 Hilux) and it shows two sensors and one with a long wire on it. Toyota bloke seemed to think there was only one sensor that did both. I checked mine and the top one has a very long wire on it.

Burstons said on mine the second one was $217 and the top one is $460 so that would be about $600 from Toyota.

So hopefully mine is the Toyota one of $330.

[Firepower2]

I just found this which is interesting:
http://highlanderclub.ru/files/manual/0 ... ip0031.pdf

[jap]

Mine is Bank 1 Sensor 2

Yours are:
Bank 1 Sensor 1
Bank 2 Sensor 1

So that is 3 sensors. I only know two sensors on the exhaust pipe but there might be more some where.

Jake has a V6.

[jakelux]

Oh yeah mate i got the sixer
Jap sent ya a PM

[toyboata]

Hi toyboata

I know it is a stupid question but when dealing with the computer I get a bit nervous.

So it is all right to start the engine with the sensor plug out so I can check the voltage on the pins of the sensor?

Apparently the other way is to put the sensor quickly in a portagas flame to remove the oxygen and test the voltage.

You need the sensor to stay plugged in for it to work and produce voltage. If you have sharp probes on your multimeter you can pierce the signal wire or use a razor blade to remove a tiny bit of insulation to expose the wire and probe it.
An NTK sensor is as good if not better than a genuine one so save yourself some bucks and get it. Also try Logicar in Dingley, I'm not sure if they sell to general public or they're trade only but they are usually the best around for price 03 9551 6222.
O2 sensors throw up a lot of different codes and the majority of the time it is the sensor and not the wiring, although poor engine/ecu earth is also quite a common and lesser known cause of issues so check them out too.
The best way to do this is check millivolts between battery negative and a good bit of metal on the engine block. With the engine running anything over 50mV is cause for concern and will require new battery terminal and possibly battery to engine earth cable.
That said it's more common on older vehicles and should not be an issue on the 6th gen Hilux but it always pays to check anyway.

[Firepower2]

I am always sticking pins through wires to check the voltage so I'll work something out there.

I'm in Brisbane but can always ring Melbourne. Toyota is $330 and Burstons up here is $217 so that is quite a bit off.

I buy most things direct from China these days but I am not brave enough to buy one of these which are a bit cheaper:
http://www.aliexpress.com/store/706439/ ... yota-.html

I am pretty sure my battery terminals are spot on but will check in the morning.

Thanks

[Firepower2]

I bought the O2 sensor No. 89465 the one we thought it was on the plan on my first post and the light on the dashboard still came on.

I bought a Toyota one so I need to keep looking for the fault. I understand that they are suppose to be replaced at 80,000klm and mine has done 150,000klm. I thought it might have been fixed as one of the voltages seemed to go from 0.000v to 0.015v.

I am presently away from home until Sunday so will not be able to put the OBD2 meter on again until then. The sensor bolted in perfectly and the electrical also went in until it clicked.

I wonder where to start looking now for the problem?

[Firepower2]

Looks like it is a visit to an auto-electrician next week. Wonder if a dynatune would be better and they pick up the problem.

The zeros shown on Bank 1 Sensor 2 is because I did not heat it up for long enough. It usually sits around .855 volts when hot which may be all right.

Apparently the "PO138 - Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2)" does not necessarily mean the sensor is no good, it can mean there is a leak on the inlet manifold, fuel injector problem.

Anyone got any ideas?

[Steve9R]

Toyboata is the man here.. He's very experienced with this stuff (as you can see from his postings)..

if however you've exhausted your options, it'll probably have to be a trip to Toyota to get it fixed..

On the same token, the majority of people on here including myself run aftermarket exhausts and have never had this issue.. have you put your standard exhaust back on to test ?

Steve