ChumpusRex

The unit isn't sealed, but there is no dipstick to check the level, and there is quite a palava to check the level and you are supposed to use a special tool to do the check and fill. The unit uses a very special fully synthetic fluid which is designed not to degrade under normal use. Under extreme stress (towing), the fluid can break down and the friction characteristics can change. The ECU monitors this, and when it detects fluid degradation it will trigger the engine management light/check VSC with a diagnostic code for transmission fluid degradation, which indicates that the fluid should be changed.

It sounds like it's trying to start, in that it is firing occasionally. This suggests that the ECU is trying to deliver spark and fuel, but for some reason, the engine is barely firing. This makes it seem unlikely that this is a major ECU failure, or an immobilizer failure. A simultaneous failure of multiple ignition circuits seems implausible. This means a fuel problem. Again, given the fact that the engine seems to fire occasionally, it probably isn't a failure of the injector amplifier, as that would result in no fuel at all. So, my suspicion is on the fuel pump - either the low pressure or high pressure pump, or the associated control system (e.g. suction control valve, pressure sensor, etc.) You need to hook it up to a scan tool and check for fault codes, and ideally use a tool which can interrogate injection rail pressure, fuel pump duty cycle, etc, or at the very least, attach a pressure gauge to the low pressure fuel line, to check that the in-tank pump is running.

The diesel engine has terrible reliability problems with the emissions system. There is also a problem with carbon buildup on the cylinder bores damaging the cylinder block and head gadket causing the head gasket to fail at 70-120k miles. This is not repairable and requires engine replacement. You would be better looking at the petrol IS250 which has similar fuel economy as the diesel, with considerably better reliability.

You can't easily drain the fluid, as only a small amount of fluid sits in the pan. You would need to take the oil pan off, and even that won't get much fluid out. The other issue is refilling it. Refilling it requires a special tool as there is no filling port.

Not the sensors themselves. The wiring. The sensors are on the midpipes, but the wiring goes up through the floorpan of the car. On some cars, this can be a nightmare, as seats and carpets have to come out. On the IS250, the connectors and wiring are in the centre console in the footwells behind the carpet. The wire then heads straight down to a hole in the floorpan. The O2 sensors come with a rubber grommet that fits into the hole.

Oh rats. Exhaust started blowing on the way to work this morning! Took it back to the garage, and they showed where it was blowing from the cracked midpipe. Their normal supplier was asking £500 for the midpipe, but I've found another supplier (www.skscarparts.co.uk) who can do a road-legal, type approved midpipe-cat with lifetime emissions warranty for about £315 (if I'd known earlier, I could have saved £150 on the front cat). Hopefully, I'll be able to organise an order from them to be delivered to the garage. As an aside, the same supplier has several different brands of O2 sensors available at surprisingly keen prices. Definitely one to keep in mind, if you need O2 sensors. As an aside, the rear O2 sensors are easy. The wires are in the footwells. Just pull the middle wall carpet out and the connector, wire and hole in the floor are there.

Yup £800 for a front cat. The midpipe has 2 cats in it which is why it is so expensive. Well, let's see what happens now. I'll be really disappointed if things start blowing, because that'll mean a new midpipe. If that is the case, I might have to take it to a fabricator and see if they can do anything with it. I'm guessing that the pipe isn't weldable. Didn't you get a custom exhaust on yours? What did they do about the cats on the midsection?

Hopefully final update. New catalyst installed, code staying away for now. A scan of O2 sensor voltages suggests that they are all switching correctly, indicating correct catalyst function. Got an aftermarket catalyst installed. Cat was £325 and it was about £225 labour from an independent garage. Very, very difficult job complicated by the fact that there were completely seized bolts needing oxy-acetylene treatment holding the 1st cat to the 2nd cat/midpipe. This heat treatment ended up warping and cracking the midpipe. This has been bodged up, but a replacement aftermarket midpipe is about £500. So, hopefully, the repair job will hold. A lexus OEM catalyst was over £800 just for the 1st catalyst. An OEM midpipe would be over £1000. No idea what caused the cat to fail. I saw the old part - substrate and everything looked perfect - so probably not a quench (which had been my original suspicion).

I've not been able to find anyone who can do walnut blasting on a lexus. Apparently the kit needs to be matched to the engine intake ports, and while there are kits readily available for BMW and audi engines apparently, no one I've asked knows where to source a lexus one, or is willing to build one given the low demand.

Interim update: Emissions tested - passed with flying colours New oxygen sensors installed Code and check VSC came straight back.

You need to have a garage read the error code from the car's ECU. Or you can purchase a Bluetooth ODB-II reader and use it with a phone app like "torque pro" to retrieve the error code.

Thanks. I've got some new upstream sensors in, and plan to change them as they are old, and even if it is a cat problem, it's probably not a bad idea to change the O2 in case that was the cause. Sorry - typo - the IS250 has wideband upstream sensors. They don't show anything interesting on the graph - the chart I've shown is bank1 and bank2 post-cat sensors. They always used to be identical, but now they are completely different, with bank 1 switching rapidly. As to emissions, I'll get that done in due course, but the IS250 has secondary catalysts, so even if one of the main catalysts is dead, the emissions may still be passable.

Just thought I'd post an update. My new O2 sensors have arrived from the USA. The code has stayed away for a couple of weeks; came back again, but I cleared it again. I've also done some more detailed OBD logging and found some old logs from my old laptop. Anyway, here's a screenshot - as you can see, currently while B2S2 switches slowly, B2S1 switches very fast. I can't think of anything that would cause that apart from a dead cat. http://imgur.com/RMIeFlj Even 5 months ago, on my last log, the two traces looked identical. So, I think that it probably is the catalyst, and that something has happened to it over the last few months. Not sure what, maybe it was when there was torrential rain a while ago, and perhaps the cat got quenched when I went through a big puddle. Thankfully, there are plenty of suppliers of road legal type-approved IS250 catalysts at a good price (I was worried about having to get one from lexus, but the cost of a brand-new aftermarket one with lifetime warranty is a small fraction of what the breakers are charging for a used cat with 80k miles on it). Will update once I get a proper diagnosis, but now that I've got the sensors in, hopefully, this won't be too much more expensive.

Just be aware, that from the factory, the polycarbonate plastic is coated with a clear silicone top-coat. This is much harder than the polycarbonate itself, and protects against scratching and yellowing. If you t-cut the silicone off, then the polycarbonate is unprotected and will scratch and yellow much faster. Not much you can do about it, if the original protective coating had failed, but just be aware that once you re-polish the headlight lenses, you'll be redoing them regularly.

Makes the accelerator pedal less sensitive. You have to push it further for the same effect. Has no effect on the gearbox as far as I can tell. Gear changes and revs are identical to normal mode.

Thanks guys. I've had a brief look and listen at the exhaust and I can't hear it blowing or anything like that. As I don't want to go taking anything apart at the moment, I did some electronic tests. I manually adjusted the lambda set point and there is a huge discrepancy in the behaviour of the bank 1 and bank 2 sensors. B1S2 is behaving strangely and seems to be reading leaner than B1S1 reads. This may well be messing up the ECU's testing. I suppose this could be an exhaust leak after the cat, or either sensor could be dodgy. I might think about replacing the 1st sensors, as they will likely need doing sooner rather than later, and it is a 1st sensor fault that could potentially damage the cat - and see if I can get the exhaust properly inspected at the same time.

Hi guys, I've been getting this code intermittently, and I've got 150k miles, so it's likely that the cats are nearly dead, but I'm just wondering on the best way to deal with this, and what the likely cost would be. The original O2 sensors are still in place, but the voltages and stuff all look legit, so they probably are still working. I think the code refers to the main catalyst which is the one in the exhaust header - so, I'm thinking that this could be very expensive. Any ideas?

There is an Osram 5000K aftermarket D4S bulb with the same light output as the OEM bulbs.

C1201 is an ABS problem, and will not cause the engine management light to come on. (VSC.traction.abs lights on) If you mean P1201, then that is an engine problem and will cause the engine management light to come on - this is a fuel injector problem. Clearing the ECU is a big no-no for fault finding, because it will clear the fault code, and delete all trace of what caused the problem in the first place. Most of the problems that cause the lights to come on will automatically reset, if the fault disappears and will be automatically deleted from the ECU if the fault doesn't occur in the next 2 engine starts. It's much easier to diagnose this sort of thing, if the code reader is plugged in while the lights are on, and the engine isn't switched off. Disconnecting the battery will completely destroy any possible chance of a successful diagnosis.

Did you check the correct fuse ("TV no 1" in the fuse box under the passenger side glove box)

I just use a bungie and some crates - keeps everything nice and organised. http://i.imgur.com/j21jbOb.jpg

The Check VSC message comes up because the VSC system is not working (it shuts off because of an engine fault). The engine fault light would be on indicating an engine problem. The way lexus have given the VSC message such prominence does seem to cause a lot of confusion.

The seat heaters have individual fuses for each seat. The seat fans do not have their own fuse. They are powered off the air-conditioning fuse.

Some cars security is not as good as the manufacturer/dealers think. My brother had an Audi A3, and locked himself out because he lost both keys. The dealer said it would be about £3k. He'd have to get the car towed in, they would need to break in, so price in a new window, he'd need new lock barrels all round, he'd need a new ECU, new security module, 2 new keys which would have to be ordered from Germany to go with the new ECU, etc. It would take a week to get all the parts ordered in. Anyway, by brother was going to be late for work, so got the train in. Phoned up some "security specialist" and gave them his home address. On his way home to meet the guy, he drew out £400 cash that the guy had asked for. Anyway, he gets home, expecting to meet the guy at 6pm. However, when he gets in a 5:30, the guy is there sat on the front wall having a ciggy. "Oh. I couldn't be bothered to wait for you to arrive, so I just started the job, and I'm done. Here are your 2 new keys. Have you got the cash?" It is possible that there is some security flaw in the lexus ECU, like there obviously is in the Audi system. However, I'm not aware of it.

Eicher are TMD friction's budget brand, made exclusively for Euro car parts, and come from their aftermarket brakes factory in Kilmarnock. TMC also make mintex, pagid and textar pads, but these usually come from the same production line as their OEM pads (where they are the friction supplier for the original OEM).