03 reg IS300 O2 sensor B1S2/rattle

[Leozack]

My 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.
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.  Lexus said the rattle may be front exhaust/heatshield issues and wanted me to pay another £800+ to replace it!

[Dean1309]

If it was me, I would get the car up on axle stands and have the car running, while its still cold, get under there and listen for any rattling at the cat. Even give it a bang and see if you can hear anything loose/breaking down in the bottom. I would rather take some time to investigate first before parting with £400 for a new cat.

I will be honest, I had a rattle with my car, you know what it was, there's a few bolts around the cat for the heat sheild. a bolt had sheered, i put a new bolt in, problem sorted. no rattle.

[Leozack]

I'd love to say I have stands/ramp and tools etc but I really don't.  I don't mind paying a mechanic to do a good job, I just don't like getting fleeced for it.

[Ben01]

Then find a mechanic you could trust. Free advices from internet don't substitute somebodys, his or yours, dirty hands and digging under your car.

[Leozack]

It's true - but yet to find said mechanic locally.  I'm more IT than mechanic - and like IT I'd love to pull it apart and fix it but that's an alternate life for me  😕

[Leozack]

I've not found a "trusted mechanic" yet as 1 of 2 local ones I tried gave me a quote the same price (or more) than lexus main dealer and the other hasn't got back to me with the quote (I guess good guys are always busy).  I've no way to get under the car myself to check for even simple things like a lose bolt on the heat shield.  The fact the sensor has gone may indicate a CAT problem but I've no idea how much it would cost to sort that out if that's the case.  It would be nice not to have the buzzy rattling though, makes my car sound knackered  😞

[Leozack]

I've been away/busy so not got this sorted yet so still driving around with the engine light on and a rattle (though strange that it rattles differently since I had the investigation work done while it was having a caliper replaced etc).  I've no way to get under the car myself and no local matey mechanic so dunno whether to go back to lexus to get the sensor done or whether that is smart considering the problem may not be the sensor but the cat or some kind of fittings  😐  Of course it could be both?