Low oil pressure message on dashboard
 

I have a 2010 GX 460 with 140000 miles. A few days ago I got that low oil pressure message on the dashboard and the car shut down. I tried to start the engine up a few times but every time the message came back up after a few seconds and the engine shutdown. I had to tow it to the mechanic. They kept the car for the whole next day but couldn't replicate that message and told me they couldn't find anything wrong with the car. When I first dropped off the car they told me it could be that the car was low on coolant and it was overheating and that could have triggered the low oil pressure message. The coolant level was fine. I drove the car home and it has been okay so far.
That warning came on around 1:30pm and before that I was on the beach the whole morning with the engine turned on idling all the time from 8 a.m. until 1 p.m. it was pretty warm all morning in the higher 80s. That warning came on as I was getting out of a car wash tunnel on my way home. Not sure if this relevant to the whole story but thought it might be interesting to share. I have not been able to drive it around much as I am at lockdown at home due to the coronavirus.
Any ideas anybody as to what can be the problem? Maybe the oil pressure sensor? Any help is appreciated.
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ok, I'll bite....

This message?

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I'm not sure why you decided to try to restart the vehicle, not smart.
Besides this decision, it is possible since the engine was idling for an extended period (and got so hot) that it started to consume oil, perhaps it was enough at an elevated temperature when the viscosity was low (oil thinned out) that it tripped the pressure switch....
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So what to do now?
1) Check the engine oil level (with the engine off) and check for engine oil leaks around the engine bay and engine oil pan (remove all the skid plates and engine garnish, get a flashlight and play detective for 30 minutes to inspect the engine....)
2) If 1 is ok and no leaks found, get the engine oil and filter changed immediately (either do it yourself or take it to a trusted mechanic). Send an oil sample for analysis (if you desire). I would want to know what the state of the oil I drained out of the engine in this scenario....
3) See if the vehicle ecu is storing any codes, historical or active.
4) The warning light received has nothing to do with the engine coolant, however in this case, I would likely drain the coolant and refill that as well for my own piece of mind... (depending the last time it was down.... if it is relatively new coolant maybe I wouldn't but if it's of unknown age and it was put thru this strenuous of an idling event, I would get it swapped out)
5) I suppose it could be a sensor going bad but I would think if the sensor was faulty it wouldn't go away or would come on randomly... if it happens again after doing 1-4, then I'd say investigate the sensor.

Lastly please think twice about idling your vehicle again in this manner... it is not a diesel engine. The systems work best and reach their optimum equilibrium temperatures when the vehicle is moving (yes the GX is liquid cooled, but the liquid coolant is air cooled via the radiator... with no air flow into the radiator, the fan likely couldn't keep up adequately with demand of the vehicle systems and began to overheat in this scenario). I'm actually a little surprised the transmission high fluid temp light wasn't received... the TC temp had to be up there!

Thanks for the quick reply and for the tips.
So idling in the summer is a bad idea as the engine will likely overheat and that leads to all sorts of bad things. I imagine it shortens the life of the fan motor too for all the overtime it has to work to make up for the lack of air flow when driving. Got it!

First thing we checked at the mechanic was the oil level and it was ok. No noticeable oil leaks or puddles either.

I'd have to check when was the last coolant change to see if it was recently. If not, coolant change it is!

Forgot to ask earlier, how likely is it that the oil pump itself is bad? I guess it would not fail intermittently. It would fail to pump oil consistently and permanently and the warning light would stay on, correct? Replacing the oil pump is major surgery, correct?

Oil cap insert
 

I had the same light come on.
Took it to a mechanic and he found the oil filter insert was missing , so the oil filter had collapsed and no oil could flow through.
He ordered the part installed it and even changed the oil for $160
The previous owner had taken my 460 to the elcheapo oil change place and they had lost the insert .
Never use quick change oil places !

If it is the oil pressure switch it is above the oil filter assembly on the driver side.

https://cimg9.ibsrv.net/gimg/www.clu...6c6691fdeb.jpg


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There is also a Low Engine Oil Sensor and corresponding warning on dashboard as well.

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Any way you can access a obd reader to verify historic faults?

Well, I've been driving the car for the last 3 weeks, even went to the beach again, with no fault, whatsoever. I am convinced it was the car wash that got some water into some connector and triggered the low pressure alert. I am replacing the oil pressure sensor anyway just to be on the safe side. I read that some of the aftermarket ones could give you a false measurement so I'm going with the original for $41 out of Amazon. Wish me luck! I'll report back if the problem comes back!

Also, i was thinking about the statement that the car should not be idled in the Summer. What happens if I live in a hot weather State and get stuck in the middle of a Traffic jam. I'm pretty sure the cars are designed to idle in the heat for a while with no problems. would be weird if i bring the car in under warranty and the response from the dealer is "you should not have idled your car in Traffic Jam". Not that the car is still under warranty but just food for thought...

It is bad for the engine to idle for long periods of time without moving. Being stuck for in a traffic jam without moving you normally turn the car off. It's not comfortable to turn off the AC and engine but one should roll down the windows and tough it out for a bit for the sake of the health of the engine. Proper airflow through the radiator is very important especially for a V8.

As posted in the manual that Nuclearn8 shared above.
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I was looking at the low oil level sensor I mentioned above.

It would appear this sensor was added in 2014 as I find no mention of it in 2010-2013 FSMs or owner's manual. It is mentioned in all '14+ documentation.

89491-60080

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Any suggestion that idling caused this anomaly is ridiculous. Water is possible culprit, but why not check the oil pressure reading with an external diagnostic gauge ? ... so as to not rely on a possible faulty oil pressure sensor ? What oil viscosity do you run ? At your mileage you may want to bump ... 0w-20 is thin even for a brand new engine if in a warmer climate.

yes, check with an external gage if possible. and the note that the sensors do not intermittently fail is incorrect. Many sensors do start to act up before complete, permanent failure.

Many counterfeit auto parts on Amazon ... buyer beware!

Skip the Amazon one, buy OE from dealerships to avoid potential headaches from the plethora of OE spoofed parts. It's too important of a part to skimp on and in this case, it isn't even cheaper.

Here's the Oil Pressure Switch for $32 from MyLParts (which is a Lexus dealer ran website from Roseville, CA). Add a few bucks for shipping, subtract 10% with code CL5 and it's comp to Amazon (and they ship fast if item is in stock).

https://www.mylparts.com/oem-parts/l...QtNmwtdjgtZ2Fz