I have a Bluetooth receiver that shows me the voltage when booting and at startup, it shows around 14.5 and later when the car is running, about 13.7, and yes, it made me skeptical too. But I had no problems with the electronics whatsoever. And I usually use the stereo around volume 40 with bass slightly turned up. But, admittedly, it could be a good idea to replace it. The things is it stacks up above an already extremely long list of expenses.

And the catalytic converter temperatures are nearly identical across the board. The only affected thing is the left sensor heater, in fine, which won't warm up as fast as the other, but eventually with the gas temperature, it does. And the engine feels healthy, by looking at the data as well as my personal impressions. The signalling part of the sensor seems to be working fine, it reacts even more than the B1 one (could be expected, it is new). But this one didn't trigger anything now. I also saw at several occasions that the back sensors are less important and don't affect the combustion or the emissions much.

2 things came to my mind:

• Regarding the ECU, if it is the cause of the problem, I think there are companies who rebuild them by replacing the bad capacitor/transistor/wire...
• I found out the O2 sensor connector was reachable by the vent under the seat. So if access to it is needed, I think just removing the driver seat and the vent cover could do.

The real big bummers would be the inside positive wire, or if the above solutions won't work for some reason.

 

You need minimum 14.4V when not using anything.

Full loaded with all options on around 13.5V.

Below 14V can causes problems.

Are all fuses checked and replaced? I did mine after 15years old.

Is your wiring/plugs not giving any resistance?

If the above is all done try to reprogram ecu or replace oxygen sensor

 

After installing my headlights, I'll take it to Lexus and give them the most details possible, including the alternator. They have all kinds of ways to test circuits and signals so they should be able to find precisely what's going on. And yes, I checked many fuses related and they are all good

 

Grab a voltmeter and test it, or take it to an auto parts store that does free alternator checks. If it is bad! make sure to replace it with oem or a denso remanufactured. Or if your low on cash hop on www.car-parts.com buy a used low mileage one, or rockauto.com they shouldnt be that expensive.

 

Thank you for the tip. I looked up and few sellers disclose the mileage, and I saw 2 had 140,000 km, so barely less than me, and if this is their end of life, this isn't a good option. If the dealer inspection confirms the alternator can relate to the problem, I'm going to do as usual i.e. order it on Lexus Parts Direct, which sells dealership parts for 10-30% less than my Lexus dealership, and have it installed by my mechanic.

 

Don't think it's an alternator.

techinfo.toyota.com

Get a 2-day standard sub, you can print/save/etc whatever you want/need for later. You'll most likely need the P0057 troubleshooting page and the wiring diagram, and then it's multimeter testing time

It's very unlikely to be the EFI MAIN relay.

 

I already have the 2 pages, but I didn't know there was a 2-day subscription. I'll remember that for the future.

 

Which two pages do you have? "The 3GR-FSE Engine Control" part of the wiring diagram & the P0057 DTC troubleshooting page?

Re: taking out the sensor - I thought it could be removed by removing the center console & lifting off the carpet there. At the very least, you can check the (presumably new) sensor for an open heater circuit or a leak between the heating and sensing circuits. Same with the wiring harness that goes underneath the carpet there.

 

OK, what I have is the ECU replacement procedure and the DTC troubleshooting page. I don't have the engine control diagram document, but in the DTC document there is a very comprehensive diagram detailing the wiring of the sensor and the ECU related to it. But removing the center console is a nightmare, I don't have a garage, it's beginning to be cold outside, I'm not too keen about diving in a complex and depressing car issue troubleshooting anymore, and I lack the complex equipment they have so I'll let the dealer figure it out.

 

Why do you need to remove the center console if you only need to probe the wires on the o2 sensor?

 

Because the plug is under the carpet near the left side of the center console. I said it is partially visible when removing the vent cover but the Lexus procedure involves removing seat and center console so not sure whether it would work.

 

Do a search I remember a member posted a short cut on getting access to it

 

I have the same but opposite code of p0158 on my 07 GS450h which is high voltage on bank 2 sensor 2. I also had the o2 sensor changed and it immediately came back on. i also saw the post about looking under the drivers seat vent. i got that far but then could not find a thing that i could get my fat fingers on so that was not much help. I am not sure if this is good for you or bad but that light has been on my car for 3 years now and still runs like a champ. I figured it might be a wire somewhere too that i would never be able to track down. Looking for an older LS now anyways....

 

"Fortunately", if we can say it that way, the rear heaters are not vital. The front sensors' heaters, however, are, because they are wideband oxygen sensors and they need to be heated permanently to work. All the rear sensors need is to be heated for a few seconds at startup, and if the heater doesn't work, the sensor will be heated shortly after startup by the gases' temperature. Hence your car running perfectly fine, as mine does.

But unfortunately, wiring can't be faulty if it brings too much current to the sensor (because being able to carry 4 amps obviously means being able to carry less). And in a video from Scotty Kilmer, on a Mercedes-Benz CLS, the HVAC computer reported a code for too much current too, and the A/C turned on an off randomly. He measured the power supply and found out it was fine, so it diagnosed a bad computer. I think chances are high you're in the same scenario.

I'm waiting for a wiring end/connector from Aliexpress (which takes a long time) to arrive because a mouse ate the wiring of my left front parking sensor. I'll have my mechanic install it, mount my bumper back into place which I didn't achieve when I replaced my headlights, and then I'll go to the dealership. I just want the car to be in the best shape possible before that, hence the delay until the next news.

 

Alright! Finally, yes, an update!

So I went to the dealership for my parking sensor, because my independent mechanic didn't in fact have the corresponding wiring diagram. At the same time I talked with the advisor about the O2 sensor. He told me bad parts are not that rare, even among the ones the dealership receives (i.e. which receive the strictest quality controls). And that they could replace it in an hour. I was astonished. I asked him about the location on the connector, the repair manual procedure I knew of etc., he told me not to worry, they've done it successfully and fried ECUs are extremely unlikely.

The dealership people were quite friendly and seemed very knowledgeable so at that point, I think I would trust him. Appointment taken for today. They replaced again the sensor.

And I have proof there's no need to take apart the center console and everything: my center console mess (secondary sunglasses, cables, McDonald's, Valentine and A&W vouchers but don't worry, I don't abuse them, I'm only 78 kg) was in the exact same position than when I let the car. And they didn't lie to me: it cost me the sensor + a hour of labor ($565+161). I have driven 100 km total after taking my car back, and no more CEL. I swear, do I regret having watched that video of a guy replacing the O2 sensor by itself with the car taken apart, making me think it was going to cost me 4 times the part in labor. This is why I instantly only saw replacing it myself as an option and proceeded this way. If I went to the dealer first, and they installed a bad new sensor, they would have replaced it for free thanks to the warranty on repairs.

I'll at least phone the dealership first next time something like this happens instead of trying to act smart.

At least this is finally OVER. And even if it wasn't cheap (the sensor is clearly overpriced), this doesn't bother me considering the expected repair costs of a luxury car. I don't take in account the price of the first sensor because it is my mistake. And the ECU is perfectly fine!