P0141 O2 Sensor Heater Circuit Bank 1 Sensor 2 - eh?

rich1068 · June 25, 2018

It had to happen. Something has finally gone "wrong" on the IS300. The engine malfunction light is on and the above code is displayed. I can clear it but it returns after a mile or two/ten minutes or so. The car was absolutely fine yesterday other than my wife had let the tank run extremely low. It still drives normally but the light is on.

I've had a look around the site and this code does get plenty of mentions but none of it makes much sense to me. So what is it and how do I fix it it? Or to be more precise, what is it and what do I need to say to someone with more expertise than me and avoid sounding like an idiot?

Is this a fairly specific fault or one of those codes you spend six frustrating months chasing? I've owned Volvos.

Dean1309 · June 25, 2018

Hi Rich, I had this on my previous IS200, I will start by saying this was a nightmare for me. I changed the O2 sensor on the manifold in the engine bay, the one nearest the front of the engine. This didnt resove it. I then changed the cat converter under the floor, this didnt solve it.

For me it was a simple case of i had just done an oil change but used Castrol magnatec grade C3, which was not burning right. I done another oil change and used magnatec A5 which i have always run my car on and this sorted the problem. Have you just had an oil change done?

If you havent, then best advice i could give is start cheapest option first. Take out the O2 sensor and check the condition of it. Is there any discolouration to it? Grey/white? I think the part number for the one i changed was DOX-0205.

Ideally you need to check if the O2 sensor is doing its job by getting a read out of the O2 sensors fluctuation. I cant advise what is correct here but a garage with the OBD computer could tell you.

But using the wrong grade of oil was the cause of my problem. There is a post on here somewhere, when i had the same issue.

rich1068 · June 26, 2018

Cheers Dean.

No changes at all other than my wife driving it

As I said, it was very low on fuel Sunday before I filled up and the handbook does mention that light may come on if you run out completely. After filling up we had a little drive and then nothing until she was leaving work last night.

I cleared the code again last night and made it nearly into the office this morning before it popped up again.

Any other information on this would be appreciated. She's taken my RX

:edit:

Another pertinent question would be am I doing any harm driving the car with this fault?

Texas · June 26, 2018

As I understand it ( but I may be wrong ) the engine in your car is the same straight 6 that is in the GS300.

So this might be useful

Paul m.

rich1068 · June 26, 2018

Thank you Paul and Dean but I (sort of) owe you an apology.

How can someone forget their car is still under warranty? I've no idea but I did The service manager at Lexus Sheffield pointed it out to me....

So basically I couldn't really care less how much the sensor is (£174 plus VAT) or how long it will take to fix.

That said, I will keep you posted for the benefit of anyone having the same problem in the future. They're also on back order from Japan.

stevlee · June 28, 2018

Search YouTube p0141 is300 and you will have a video on exactly what is needed

rich1068 · July 6, 2018

Little update.

I got the call this morning from Lexus Sheffield to say the part had arrived from Japan. They're fitting it this afternoon.

How's that for service?

rich1068 · July 6, 2018

Here's a question for the more technically minded.

Could these sensors start to fail or do they just fail? Is it possible that there's a slow deterioration in performance due to a failing sensor then one day it goes and bingo, the light comes on?

I ask because Lexus Sheffield did the job in a couple of hours this afternoon (1h55min for the engine to cool down, 5min to change the sensor) and the car was noticeably perkier especially from standstill. What I've been putting down to a bit of play in the throttle seems to have disappeared.

Anyone?

ColinBarber · July 6, 2018

The heater part of the sensor just fail, the element burns out and instantly becomes a hard fault.

O2 sensor itself start to become slow to react which effects performance and economy. Even before they generate a fault you can benefit from them being changed.

rich1068 · July 7, 2018

12 hours ago, ColinBarber said:

O2 sensor itself start to become slow to react which effects performance and economy. Even before they generate a fault you can benefit from them being changed.

Interesting. So I might not be just imagining it? I've been promising myself for months that I'd do the throttle mod as described here and on the US forums but I really don't think I need too. Could have been this sensor all along.

Anyway, I'm driving it again to today. I'll see if it has actually improved things.

Leozack · July 10, 2018

This sounds remarkably familiar since by 03 reg IS300 had the engine light come on a month or 2 ago and I borrowed a friends OBD2 to see that it was O2 bank1 sensor2 at fault. We reset it but it came back on the next day. I've since had a bunch of expensive work done by the main dealer to fix other problems (caliper, pad, disc etc) but they had to wait for the sensor to come in stock. It's now come in stock but it was about £250 all in which I found too expensive. I've since gone to local recommended garages (Bristol/Bath) and the only quote I've got back was about £280 which shocked me. If it is indeed the sensor just off the side of the engine then it is very accessible and I'd be tempted to change it myself if I had the right tools. I've definitely not just changed my oil!
However I'm unsure if a sensor change will fix it since another issue I've had is a slight rattling (particularly when idle in drive) over a year or so that noone has diagnosed but now the local garages suggested since this sensor is related to the CAT that it may be the CAT that is rattling. This kinda scares my wallet a bit but it would be nice to sort it.

rich1068 · July 10, 2018

Not sure about the problem or connection with the cat but changing the sensor did the trick for me. If you're having the work done at the dealer that price sounds about right too. IIRC the sensor was north of £150 plus labour plus VAT. It wouldn't be massively cheaper at an independent.

Something I have noticed though. Before remembering the warranty (doh!) I approached this in the same way I did with European cars I've owned previously. Engine management light, vague code, feeling of dread that this will involve throwing parts at the car until by chance it's fixed. I've had Volvos of the same age that have cost £££ in "it could be this" parts. However, more or less from the start on here, at Lexus and from other sources the response has been the same. It's this part you need. Very specific and a refreshing change.

Leozack · July 10, 2018

Does anyone have an idea what it might cost if the cat is the problem with the rattle/cause for the o2 sensor reporting a problem? It would suck to pay to replace the sensor only to find it lights up again. I mean the main dealer thought the rattle might be the front exhaust/heatsheild and want me to pay about £900 to replace it @_@

Dean1309 · July 10, 2018

26 minutes ago, Leozack said:

Does anyone have an idea what it might cost if the cat is the problem with the rattle/cause for the o2 sensor reporting a problem? It would suck to pay to replace the sensor only to find it lights up again. I mean the main dealer thought the rattle might be the front exhaust/heatsheild and want me to pay about £900 to replace it @_@

Hiya mate, when I was going through this problem and had a new cat fitted, mine cost me £400. Are they having a F**king joke, £900 to replace the heat shield, WTF!!!! its held on by 4 bolts. Source one from scrap yard and fit it yourself.

Dean1309 · July 10, 2018

1 hour ago, Leozack said:

This sounds remarkably familiar since by 03 reg IS300 had the engine light come on a month or 2 ago and I borrowed a friends OBD2 to see that it was O2 bank1 sensor2 at fault. We reset it but it came back on the next day. I've since had a bunch of expensive work done by the main dealer to fix other problems (caliper, pad, disc etc) but they had to wait for the sensor to come in stock. It's now come in stock but it was about £250 all in which I found too expensive. I've since gone to local recommended garages (Bristol/Bath) and the only quote I've got back was about £280 which shocked me. If it is indeed the sensor just off the side of the engine then it is very accessible and I'd be tempted to change it myself if I had the right tools. I've definitely not just changed my oil!
However I'm unsure if a sensor change will fix it since another issue I've had is a slight rattling (particularly when idle in drive) over a year or so that noone has diagnosed but now the local garages suggested since this sensor is related to the CAT that it may be the CAT that is rattling. This kinda scares my wallet a bit but it would be nice to sort it.

£280 for a sensor, yeah right, I paid either £60 or £90 for the sensor think the part number is DOX-0205 which the denso OE part number, you havent got to have the removal tool, i dont mine with a pair of mold grips / mole grips what ever their called, and used WD40 around the thread. Unscrew the sensor and screw new one in.

Leozack · July 10, 2018

Yeah the £900 odd was for the front exhaust system and possibly heatshield fitted. But 1 that's a lot for just front exhaust 2 it might not even be the cause. I mean the rattle doesn't even sound the same since it was in for the other work so poking around he obviously changed something already!
The sensor seems about £100 looking online earlier but I wouldn't know the perfect one to get. Happy to consider DIY though I'm defo not a mechanic and the last time I DIY'd discs/pads etc things weren't ever quite right. But the thing putting me off changing the sensor straight up is what if it isn't the sensor's fault and it is related to the rattle/possibly the CAT etc 😐 Hmmm