Oxygen / lambda sensor fault

[Rangor]

Hi all,

I'm after some advice for my toyota avensis T25 (2005) 2.0 vvti.

The engine warning light came on a few weeks ago, so i bought myself an ODB-II bluetooth gizmo and downloaded the Torque app for my smartphone.

The fault was diagnosed as a fault on oxygen sensor Bank 2, sensor 1. After checking these forums for advice I disconnected the plug socket and tested the resistance between the two black wires and this was not as it should be. Apparently this indicates that the heater element in the sensor is not working correctly.

Using the Torque App on my phone and the ODB-II link I could see that the while the engine was running the voltage on the O2 sensor (bank 2, sensor 1) was always 0 v, whereas the other oxygen sensors would range between about 0 - 1 v.

So I replaced the oxygen sensor with a new one from Denso. This required me to swap the plug socket from the old one to the new sensor, as the new one from Denso had a different connector shape. I cut the wires, bound the new sensor wires to the correct wires on the old plug, soldered them, and put shrink wrap around the joints.

Measuring the voltage range for that sensor using the ODB-II link shows it seems to be working and ranges from 0 - 1 v like the other sensors. With my foot off the accelerator the voltage remains at zero, but as rev the engine the voltage increase. Suggests to me that the sensor is measuring stuff and I've fitted the sensor, and rewired the plug correctly.

However, I've tried to reset the fault code on ECU, and the engine warning light goes off momentarily but then comes back on with the same fault code.

Can anyone suggest what else could be wrong, or whether I've done something wrong in fitting the sensor to keep giving me the bank 2, sensor 1?

I've spoken with a local Toyota garage and they are saying they would just replace the Denso sensor with a Toyota one at a cost of about £250 incl labour. Don't really want to do that especially as I've already spent about £150 on the Denso sensor and tools.

Many thanks.

[ents]

Local Toyota garage would just replace the Denso sensor with a Toyota one!

It would still be made by Denso!

Since you replaced the plug, that indicates you bought the wrong sensor, what was the number on it?

[Konrad C]

Rangor, when you said you had to change the connector on the Denso sensor, this tells me that you didn't get the correct one for your car. It must have been a universal version!

I have changed the sensor on my old Avensis, and it is the correct rating. I also had to repair the cabling on the sensor once, when it was cut by the air-con fan. It always worked. Another thing, sometimes there is a slight variation between the sensors for the automatic and manual transmission cars.  

Here is the link to the catalogue:- http://www.denso-am.co.uk/media/102388/dels14-0001.pdf

Scroll to page 170 and you will see part numbers for different 2 litre petrol engines.

I noticed that Ents has also replied whilst I was typing this.

[Rangor]

Ah, balls. I thought I'd bought the right one (from Eurocarparts) as the website said it was the correct one, but when it arrived i realised the plug didn't fit. I bought this one: http://www.eurocarparts.com/ecp/c/Toyota_Avensis_2.0_2005/p/car-parts/car-body-parts-and-car-exhaust/exhausts/lambda-sensor/?710824605&1&4eef6017dc52dce5c409b432d4359f122b742421&000210

or if the link doesn't work its Eurocarparts product number  710824605

I'll have a look at the Denso catalogue and find the right one.

Many thanks for your help. 

[+robster+]

bank 2?

is it a v6 engine?

you probably have a generic code

look for Toyota specific code

what was the code?

[Rangor]

I can't remember the specific code (P0051 or something), but I also tested the plug socket in question and it's resistance was 0, rather than 3 ohms like the others and what i replaced it with. I could also see that this sensor was giving 0 V whilst the engine was running, using my ODB and Torque app on my phone, so I'm sure this is the correct sensor.

 

[Rangor]

I've now bought the correct Denso sensor with the correct plug socket. The only problem is I can't remove the universal one I put in to replace the broken one!

I'm using one of these (http://www.halfords.com/workshop-tools/tools/hand-tools/laser-oxygen-sensor-socket-22mm-3-8-drive) to remove the sensor in the same way I removed the original broken one. But trying to remove the universal one all I've managed to do is shear off part of the bolt on the sensor. I stopped what I was doing rather than make it even worse.

Has anyone got any suggestions of how to remove the sensor without shearing off more of the bolt? I'm thinking I should just take it to a garage.

[frankie406]

Could possibly heat the engine/exhaust to see if that would help it a bit.

[waqar_lionheart]

Blowtorch heat application. has happened to me as well. 

[Owdjockey]

Hi Rangor, apologies if you did this already, but did you apply the correct torque when installing this sensor, it should be in the range 37 - 47 Nm. Did you also carefully apply anti-sieze lubricant to the threaded portion of the sensor?

Cannot understand why it has seized in such a short space of time. As Waqar suggests, get some direct heat on it.

[Rangor]

Thanks for all the tips chaps. I ended up using a proper socket and breaker bar, and the sensor came loose with ease. I did have to destroy the sensor to get the socket to fit though.

I noticed that on removing the sensor which had been in place for about 4 week (~ 500 miles) it was already quite coated in black soot. I fitted the new sensor which has the correct plug socket on it and is correct according to the Denso catalogue. I cleared the fault in the ECU, but after starting the engine the fault came back on within about 10 seconds. I'm thinking something else is causing the problem. I'm pretty sure I've identified the correct sensor (the code is P0052). 

 

[+robster+]

Does it have 2 lambda sensors?

 One being pre cat and one being post cat? Hence is it correct one youve done?

P0052 as far as i can see is lambda heater circuit high as in too much voltage.

Sounds like low resistance on heater causing high voltage feedback could be sensor. Could be wiring could be exu fauly

Try locate and remove relay or fuse for this circuit and it should change code to p0051 as low voltage fault

 

If it stays high then id say ecu is not measuring correctly

[Konrad C]

Look at the link below, especially Ents reply and the diagrams showing the 4 sensor location. Robbie's suggestion to reset the ECU may help get it running properly.

I think that the sensor which was wrong for the car caused the ECU to give the wrong settings. Clearing the ECU so it can relearn may help. Normal, once the correct sensor has been installed the EML goes out. If it comes back on then there is something else wrong. I am fortunate to have my own diagnostic device which works on most cars, is upgrade-able, live data, and will tell what the code means. If you have access to diagnostic kit, which you seem to have, you can try and see what is going on.  

[+robster+]

read that post

I'm used to banks 1 and 2 being for each head/manicat

the whole bank 2 is becoming clearer on this engine now

all 4 cylinder engines ive seen have 2 lambdas maybey a third further down the line , including flat4 boxer have both manifolds to a link into one then to turbo then to one cat with a pre and post lambda

this shows  a manicat that is segregated for cylinders 1/4 ans 2/3 and has defined as two cats and two banks just like a v6 etc has 2 manicats

anyway hope you are on the right lambda of the four shown

you should be top left looking at manifold.

 

on another note

is it zirconia type lambda

id get a £20 universal

have used them in the past just attach your plug

 

[Gary Stephen's]

We have a Toyota rav4 2004 and the engine management  light  came on 2 years ago, I took it to a garage and he plugged it to the machine and found it was a first stage sensor, we had it changed and when driving long distance, the light came back again.

We had the sensor changed for a bosch  sensor the next year and the light is still on.

What else can be the problem before I send it to a garage for expensive repairs??

 

[paul9]

Air leaks in the intake path can make the ECU believe that the sensors are faulty, as they will change the amount of air the ECU thinks the engine is using. The ECU will measure out fuel based on the amount of air it thinks the engine is receiving, which will be the wrong amount. Then the engine burns rich or lean, and the ECU gets confused when it can't properly adjust the fuel trims. A dirty or faulty MAF sensor could cause similar problems. Just a couple of things to check on.