Oxygen Sensor

seaside shuffle · January 31, 2015

Hi Al: Thought I would check with you all on your thoughts to my recent shock.

I have had my 2006- IS 250 SEL Auto - mileage of 75625 for 6 years and for the first time ever warning lights appeared - Check VSC, ABS, Red Warning Triangle and the Engine Management Warning (not flashing).

Had the ECU code read by my local garage (not a Lexus agent) - came out as:

Confirmed & stored codes:

ECU E8....DTC P0031 HO2S Heater Control Circuit Low (Bank 1 Sensor 1)

ECU E8....DTC P0051 HO2S Heater Control Circuit Low (Bank 2 Sensor 1)

.

I am correct in assuming that the lies with Oxygen Sensors?

If so is this a common or rare fault - how come two sensors seemed to have failed together?

Finally in anyone's experience - Is it safe to use until corrected. And any idea what sort of expense I am in for If I have to use my local Lexus Agent (at £110 per hour)

I must admit I do not use a Lexus agent to service the car (cost reasons) but a local well established garage who has serviced and maintained it for me.

Thanks - Rob

is200 Newbie · January 31, 2015

The sensors require changing between 70 and 100k, you will find (I was told) that they usually fail within this period.

One of mine went last year but I decided to replace both as they were both original parts and best to replace them together. An easy job to do yourself. I posted a how to on the forum for changing both.
I think it took around 2 hours to do but I took my time. Parts costed around £150 from the USA ... Quoted from Lexus Chester for the replacement of both was £680.!!
While I was waiting for the parts I had no choice to run mine off and on for a week .. The only result in that was I noticed a bit of sooting up on the exhaust tips.
I must say though, after replacement, there is a noticeable difference in petrol consumption (better)

toffee_pie · January 31, 2015

680quid.......!

is200 Newbie · January 31, 2015

Chester quoted 680 for the parts and fitting - 180 I think per sensor - buying from the states was a lot cheaper although there was a wait for them but by the time it would have taken to book the car in to get them done then its probably quicker doing them yourself.

toffee_pie · January 31, 2015

Yeah, i got spark plugs from USA too, many parts for the is range seems can only be got from there, which seems mad

simply no market for this car in England.

agent_dess · February 1, 2015

Eurocarparts have a Denso lambda sensor, part no: 710822605 doesn't tell you what Denso model no it is though but I put in my car reg and it came as suitable for my car. Priced at £81....

http://www.eurocarparts.com/mobile/search/710822605/p/home

Anyone know if this is the part I need?

johnatg · February 1, 2015

That's listed as fitting extensively across Toyota vehicles and including IS200 and IS250. So it will most likely fit and work OK. One caveat - the guy who does electronic advice in 'Car Mechanics' mag always says to fit a genuine oem oxygen sensor - maintains they give better results than generic ones.

But this one could well be oem anyway - after all, Denso supply IS250 spark plugs, so why not oxygen sensors? And this looks like a good saving.

agent_dess · February 1, 2015

Yeah it's a cracking price ands it's Denso so don't think you can go wrong... But I noticed there are 4 sensors on the car with 2 being located on the engine bay and i believe the other 2 on the exhaust... Are all 4 sensor the same product? The 2 in the engine are air/fuel and I think the other 2 are heat related? The reason for me wanting to change mines is I sense a strong smell of unburnt fuel, cars hit 82k never used to smell it before.

johnatg · February 1, 2015

I think they're the same - need to check the part numbers. Does someone here have a parts list?

The 'engine bay' ones are the main sensors, used to adjust fuel/air ratios. The ones further down the exhaust are post-cat - they are used to check that the cat is doing its job by comparing O₂ exhaust content with the pre-cat readings (some predictable amount of O₂ is used in the cat process)

Correction 7/2/15 - they are NOT the same. The upstream ones are heated, the downstream ones are not. The connection plugs are different.

toffee_pie · February 1, 2015

Eurocarparts have a Denso lambda sensor, part no: 710822605 doesn't tell you what Denso model no it is though but I put in my car reg and it came as suitable for my car. Priced at £81....

http://www.eurocarparts.com/mobile/search/710822605/p/home

Anyone know if this is the part I need?

Denso are reputable, but is it the right part.?

ChumpusRex · February 1, 2015

The denso part number requires is 234-9051

agent_dess · February 1, 2015

Thanks for the part number ChumpusRex will check with eurocarparts tomorrow.

ColinBarber · February 1, 2015

I would never expect two sensors to fail at exactly the same time - it could happen but very unlikely. For the heater circuits within the sensor that is like two headlight bulbs going at exactly the same time, and not just burning out but creating a much more unlikely short.

Personally I'd want to check voltage is getting to the heater pins on the sensor(s) first and check the wiring back to a connect connector block. The heaters are also potentially driven via a relay which could be checked.

Another possibility is the ECU could have just been having a moment, I'd clear the codes and only proceed if the errors come back.

seaside shuffle · February 1, 2015

Thank you all for your concerns and advice - I have to agree with Colin as to why both are registering a failure at the same time - seems a bit odd. Anyway so far all that's been done is the ECU read-out I now have to get 'the man' who looks after my car to have it in his workshop and investigate further.

I did however phone my local Lexus agent who has quoted £600 to replace both. (not too happy about that - but hey that's Lexus price). Hopefully 'My-Man' can fix it for far less as it's something that I have no idea or the mechanical know-how to do it myself.

Will report back when it's all sorted (hopefully soon)

Rob

agent_dess · February 6, 2015

Got email back from eurocarparts they say the Denso lambda sensor is part number DOX-0277

is200 Newbie · February 6, 2015

I would use an OEM part to replace this as its an important part that will control how the car will run.

When I was looking for a replacement sensor I found quite a few cheap ones which were the sensor only (meant to solder onto the existing wiring) and ones other than OEM but a few searches found the non OEM ones were not that reliable - if you see one that's been removed from use you will see why as it does get caked on "soot"

I have included a picture of a good sensor, cleaned up a bit (I replaced both of mine even though only one had gone as I thought they had been in the car for the same time - makes sense to do both while you are in the engine I think) - very big noticeable difference on petrol consumption and a relatively easy job to do.

Two pictures below - one of the removed good sensor and one of the part number on the box the replacements came in. By the way this part number is ok to do both sides as the wire is long enough for the left and right banks. See my post on how to replace both banks.

agent_dess · February 6, 2015

Yeah gonna order 2 in from the U.S. then, fuel consumptipn is crap these days combined with a rich smell of fuel when outside car.

ChumpusRex · February 6, 2015

Got email back from eurocarparts they say the Denso lambda sensor is part number DOX-0277

That is the wrong part. It's a "sensor 2". Your error codes point to "sensor 1".

It's a bit odd for both sensor 1s to fail simultaneously. I'd strongly suggest getting the wiring checked to make sure that it's not a wiring problem between the ECU and the senors (or a faulty ECU), or at least be prepared that it could be a wiring fault, if you replace the sensors and the fault is still there.

seaside shuffle · February 7, 2015

Update: Having the fault codes re-checked - plus wiring checked - but have to wait until next Thursday - the suspense is killing. Will update when I know more.

Thanks again for your all your advice and information.

Rob.

ColinBarber · February 7, 2015

according to Denso's European website they don't market a direct fit sensor in the Europe, they only list DOX-0109 as universal fit downstream sensor which means you have to cut and solder the wiring, no upstream A/F sensors.

http://www.denso-am.eu/e-catalogue/

Use Denso's US site to find the correct part codes and order from a supplier in the US, for example rockauto

http://densoautoparts.com/find-my-part/vehicle-selection

agent_dess · February 9, 2015

There out to be European equivelant to the Denso 234-9051, I don't see why we should have to order from the US?? Maybe give Lexus parts dept a call and see what part and price they come back with.

is200 Newbie · February 9, 2015

As with Colin above who pointed me in the right direction when mine went - if you want the correct OEM sensors then you need to source these from the USA.

And like previous posts and what Colin has also confirmed, the cheap ones will require soldering to the existing wiring.

If you do opt for the cheaper ones and solder them then you will have to remove all of the parts you will have had to remove if you had bought the OEM ones so its false economy really.

Cost for mine fitted (for 2) was £680 through Lexus - cost for parts I sourced from the USA was £150 but I fell lucky in not paying duty.

To be honest, the longer you leave it, deciding what to do and searching for them in the UK (and they are not available here unless purchased from Lexus probably on a weeks lead time), then the longer the car will be running rich unless its off the road in the meantime.

Sourcing from the USA will take a week and a bit to be delivered so you need to factor in this time to get them delivered and possibly another week to get the car in to the garage to get them fitted unless you are doing them yourself - frankly, seeing the state of one dead sensor I took out of mine I personally would not run the car with two gone so the longer its left the more damage could be occurred.

The only damage I can see this creating is cokeing up the cats and also damage to the down stream air sensor 2 (one on each pipe) ... if your cats do go (not sure how hot they get to burn off any soot/fumes) then you will be looking at a few thousand pounds to replace your exhaust and a further sum in replacing the sensors.

steve2006 · February 9, 2015

Both of the precat O2 sensors were faulty with open circuit heaters on my now looong term Celsior project but this may have been due to running it with a misfire as a result of a faulty coil.

Checking heater continuity is easy to do with a basic digital multimeter,if you don't get a reading they are open circuit.

Think of it as a light bulb,if the filiment is intact the bulb works if it is broken it won't.

seaside shuffle · February 9, 2015

Update: Whilst waiting for this Thursday to come when my local garage has the time to re-check and investigate further, I am only using the car to travel to work and back (6 miles each way). So approx. 70 miles all in. Did not use it Saturday. Washed it Sunday (have to keep it clean - it's a Me-Thing). This morning, Monday it would not start - just turned over & over, on the third attempt it bit but sounded as if only running on 2 pots, switched off and left it on the driveway - contacted the garage man who's going to check it out tomorrow. He is only willing to spend a couple of hours on it and then leave the decision to me.

I am getting ready to contact my local Lexus garage and face what I've been dreading. ££££££££££££££££££££££££££££££££££££ Oh well if I want to run my Dream Car then I have to accept the financial demands. Hopefully it will not be totally bad news - I've had 4 years trouble free, but after all it is only 8 1/2 years old.

To answer Noo Bie - I did check with Lexus when the read-out reported the 2 faulty sensors and they said it would cost around £630 (including parts & VAT) to replace them.