oxygen sensor

[Sherra]

Evening all readers

I have the code for 02 sensor appear. Question is how best to access the pre cat sensors, sensor 1 on my GS450h, from bellow or above. I have been unable to find anything on here or club lexus or google. Can anyone advise please before I get too involved. Also can they be swapped bank to bank to aid elimination.

TIA Paul

[cruisermark]

If the LS430 is any similar it would done from underneath.

One word of advice - don't buy the sensors without the plugs - buy one with a plug - swapping over will be simpler.

Not sure how you checked the code - but it should tell you which one it is for example Bank 1 Sensor 1 would be passenger side pre-cat on the 430

[Sherra]

Checked using both my sons blue-point reader and techstream. just thought if I could swap bank 1 to bank 2 it would confirm sensor fault as opposed to other. Its showing bank 2 sensor 1 at fault.

[The-Acre]

1 hour ago, Sherra said:

Checked using both my sons blueprint reader and techstream. just thought if I could swap bank 1 to bank 2 it would confirm sensor fault as opposed to other. Its showing bank 2 sensor 1 at fault.

On my ex GS300 I did the pre cat sensors from above, certainly the drivers side is fairly straightforward. As long as the wires are long enough I don't see why they can't be swapped.  I believe it's the downstream sensors that have very different wire lengths.

[Sherra]

Unfortunately Phil I don't think there's as much room on the 450h as there is on the 300 and there's not much room on that. Was there a lot of stripdown to gain access?

[The-Acre]

2 hours ago, Sherra said:

Unfortunately Phil I don't think there's as much room on the 450h as there is on the 300 and there's not much room on that. Was there a lot of stripdown to gain access?

It was two years ago so I can't remember exactly, but I really don't remember doing much stripping down at all, just a bit of plastic.  The hardest part was getting the plug to disconnect as there isn't much room to get your fingers in. I used a small o2 sensor socket (the one where you put another socket off centre) which made access easier and soaked it first with penetrating fluid, ideally overnight. I guess being a hybrid you've got other obstacles to contend with.

[Sherra]

many obstacles if I have chance I'll post a photo.

 

Edited December 15, 2019 by Sherra
add Photos

[Lwerewolf]

Ouch, inverter...

I just did this on a LHD car - it's the bank 1 sensor in my case, should be similar.

Disconnect Battery service fuse, disconnect 12v, wait ~30 minutes, remove inverter top cap, remove the small lid on the sides (2 screws, it has a gasket and a circuit breaker so it doesn't just lift off - do it slowly and carefully), measure voltage at the terminals (max - 650v, you want 0v). If 0v - proceed, if not - wait. Disconnect the MG1 & MG2 cables (the 2 big AC ones at the front) - side screws first, then the middle. They are heavily waterproofed, so draw them out carefully. Remove the water lines towards the inverter - the front one at any rate... you might want or have to remove the reservoir with the rad cap - on LHD cars it's not near the inverter. Your call, just make sure that coolant doesn't spill on any electrical connections - plug/seal everything off once you disconnect it. Then there's the inverter bracket, and probably the EPS (power steering) ECU on or below it... and a nasty plastic uhh "clip" holding a bracket to the plastic protective casing around the wires that go from/to the HV Battery - I don't remember how we got it out with the mechanic, but it wasn't damaged, so... improvise 🙂

After all of that, the o2 sensor was visible - a torque wrench did fit, in case you want to bother to torque it to spec (gs300 is 40 or 44nm, same sensors).

AFAIK the service manual for the hybrid calls for the removal of the engine and the transmission - at least on the lhd ls600h it does specify that. The GS300 LHD one calls for the removal of the Battery (which is where the inverter is on these cars) and the power steering ECU... so there's that 😛

The inverter water pump runs ~20sec after the car gets into "ready" mode - Techstream can also start it when in "IG ON" (double press "power" without holding brakes). The service manual says something along the lines of filling it to level (by opening the bleed port on the front of the hybrid radiator and, if LHD, next to the inverter, attaching see-through hoses to them, and fiilling with SLLC until the reservoir is full), and then to run the pump in 30sec intervals, topping off as needed. The 4th gen (and just about all other hybrids) is way, way better in this regard...

Good luck if you haven't done it already. Weirdly enough, in my case, before the o2 codes I had both p0420 and p0430 (cat codes) - checked for exhaust leaks (blocked exhaust on the rear, visual inspection for soot all over the place, replaced catback with new OEM one, removed heat shields post the secondary O2s as preventative measure, replaced all gaskets post-headers), did the oxygen storage test (forced lean/rich mixture in techstream - the rear o2s reacted with >2sec. delay, so all "good"), etc... then my bank 1 AFR (o2) started giving codes ("stuck lean", then progressed to 3 others, I suspect the heater circuit shorted, the waveform was fluctuating wildly, and the heater is PWM controlled - hence my guess - in the end, the heater circuit went open), new one arrived, changed on the same day, expected cat codes... two days later and 6 trips (cold start, hot start, sloooow city driving, highway driving, etc, checked emissions readiness results after every one of them - cats were measured each time, slightly jittery results as expected), no codes. No clue how a single AFR threw off the mixture or whatever on both banks - maybe the ECU was throwing off the MAF calibration or something...

[Sherra]

Alexander

As I have serious heart problems and a bad back I chickened out and have booked it into Lex-Tek  Autos at Sheffield for after the new year. I could just about stand up after my initial investigations which influenced my decision and after reading your case I am reassured for me that its best. Not beyond my skills but not the physicality.

[cruisermark]

Should be a straight forward job for dave - hopefully your car will be back to normal soon

[Sherra]

Hopefully Mark, its the first time using him but have not heard 1 bad report.

[Lwerewolf]

Ehh, just a quick update on the optimistic p0420/p0430 in my case - they're back. It seems the ECU sets a lower failure threshold immediately after a memory wipe, the exact thresholds and mechanics are not clear ("toyota confidential" or whatever). Sorry if I got anybody's hopes up on that one.

[Sherra]

Update

Dave at Lex-Tekautos fitted a new sensor for me today and all seems fine but wallet considerably lighter. Its the first GS. 450h he's done and was surprised at how much he had to dismantle to gain access.

[LexIS200Sport]

Hi Paul, do you know if he gained access to the sensor from above or underneath? Was the exhaust manifold amongst the items that he had to dismantle?

 

[Sherra]

Ganesh,

From above, same method as Alexander above used apart from removing coolant reservoir. He said it was extremely physically tight to get his hands in and the sensor tight, but that's common.