BinaryJay

Here is Lexus' diagnosis. Small exhaust leak under certain conditions in the Y pipe ahead of the O2 sensor. Told me basically replacing the whole pipe would be over $1500 so suggested I just take it to a muffler shop and have them cut it and weld a new piece on.

Only problem is by the time they got to listening closely to find the exact location of the leak they said the exhaust was too hot and they couldn't find it. It is either in a small crack somewhere in the pipe or a leak from the gasket at the flange.

Anybody have any experience with muffler shop costs for this kind of thing?

Doesn't really answer any questions about the smoke screens before though.

BinaryJay

Update...

1) I no longer think it's an exhaust leak - muffler shop couldn't find anything.
2) The high voltage/shorted to voltage O2 sensor code seems DEFINITELY related to water... first happened during driving rain, in between wasn't paying much attention, last occurrence happened after a drive through automatic car wash.
3) Seems to go away on it's own during a period of time that would match what I might expect from water draining/evaporating.

So my new theory is:

1) Windshield cowl drain(s) are blocked causing water to build up in there and eventually overflow down the firewall into the passenger footwell compartment and soak the rear passenger side O2 sensor harness which I think is located there.

2) Windshield cowl is deformed allowing water to get down into areas at the bottom of the windshield it shouldn't... the rubber piece along the windshield that should seal pretty tightly against the cowl no longer does. I'm not sure if this is really an issue or not.

I found the redesigned cowl that they started using I think in the 2010 model year which was supposed to I think resolve some squeaking noises (which mine does) due to the cowl fitment against the windshield on eBay from a recycler for $65 and bought it. My previous solution to the squeaking was pressing foam in between the cowl and the windshield but that probably just made the water infiltration problem worse (I wasn't even thinking about that at the time).

I figure if I remove the old one and break clips because I don't know what I'm doing at least I have a new part and hopefully the new part solves the squeaking and at best the possible water o2 sensor harness issue.

So two questions-

1) Does my theory make any sense?
2) Has anybody removed the cowl on their car before and have any tips? It seems like there are some push type clips at each side and then some clips in the middle - which I'm fairly sure mine is missing. Any idea how many clips there are etc?
3) How can I easily clear the drains with the cowl off? Do I have to locate where they exit at the bottom of the car? Any idea where?

Basically I want to get the old cowl off and try to clear the drains and then replace with the newer redesigned cowl.

ibidu1

iTrader: (1)

Ive had this problem on my 08 gs350 AWD the y-pipe leaked, I took it to a muffler shop and they just welded the pipe together. $20.00 bucks later no noise. They removed the exhaust clamp, the silencer plate.

ibidu1

iTrader: (1)

Even if you had water blockage a wire is insulated, unless there was a connection to it that is messed up and allowing corrosion in. Like I explained before you need to have a good mechanic test the o2 sensor wire clean it and test it for any possibly shortage.

I wouldn't take it to lexus, they will only charge you an arm and a leg at trying to diagnose stuff. Take it to a small experienced mom and pop shop

TWong350

iTrader: (8)

Jay - Out of curiosity, how's your fuel economy? How long has this been going on? Losing any coolant? The white smoke indicates water. I would yank the plugs from the bank in question and see what they look like. If they're really clean, could be indicator of water entering some how.

See attached TSIB for this code. Keep in mind that this TSIB is for US models.

BinaryJay

It's hard to say, it seems somewhat normal for recent driving habits but it's always a bit higher in the winter because of the gas difference... Also, my wife has been taking the car to work a lot more this winter than usual where she would usually just take the subway and that is an all city driving trip so the ratio of city to highway driving has changed a lot. At any rate, it really doesn't seem super significantly off - the on the fly readout usually shows in the neighborhood of 26-30 mpg when cruising at city street speeds. Of course when I floor it on the highway, it just "tops out" on the graph and it stops showing me the actual usage after around 11 mpg (my car shows L/100 km not mpg, just converting here... car stops reporting anything higher than 20L/100km).

It's also really hard to say one way or another in this sub freezing temperature if it's just normal steam or what, but it certainly doesn't seem at least driving around normally or idling that the amount of steam is any different than other cars around... just not sure about if WOT should produce more steam with more combustion but that makes sense to me... it's kind of the thing that I need a warm spring day to see if it still happens or not.

Coolant levels seem fine, it is up near the full mark on the overflow when hot - I had the coolant replaced in the summer but I didn't really pay attention to the levels they left it at. Smelling the exhaust at least when it's idling does not smell like coolant it just smells like exhaust really. Under the oil fill cap it all looks clean without any condensation, there is nothing but clear oil on the dipstick.

P.S. That TSB was actually performed already when the car was under warranty, they said there were no readings from my O2 sensors and did it but at the time I didn't even bring the car in with the dummy lights on but I wasn't going to argue with a new ECU and set of sensors.

What doesn't make sense to me is why this is so connected to when the car is exposed to a lot of water and a day or so thereafter, unless something is getting wet and causing a short... either there is a harness in the engine bay (I don't think so?) for the rear O2 sensor or the only other spot where a harness could get wet is in the cabin near the firewall from what I can gather and the only way that that area can get exposed to water is through the cowl drains overflowing at least usually. I never did check the carpet for wetness... I have rubber mats down that would certainly hide it. You would think all harnesses are waterproof even in the cabin, but maybe it's a combination of water getting in there and the harness not being snapped tightly in after they replaced that sensor for that TSB.

It's really getting my goat though and it's so damn cold out that I loathe the thought of going out to the driveway with my tools to start farting around, and I'm kind of afraid to go through the carwash again now just to test my theory until I at least take some action to check those drains.

I have no idea what the entrance to the cowl drains looks like under the cowl cover yet or what the diameter of the tubes are (to get an idea what kind of snake might work best), but I wonder if I could treat any clogs chemically - like pouring liquid plumber/drano down the inlets to the drains with the cowl still in place, leaving it for a while and then flushing it with boiling water or something... I have yet to come across any anecdotes of car drains being cleaned with plumbing clog cleaner so I think this may be a bad idea though I can't think of any reason why yet. Alternatively, with the cover off, perhaps pouring baking soda down there followed with vinegar and plugging the top of the tube with my thumb or something to force the bubbles to push any clogs out the bottom.

At any rate I hoping taking that cowl off is simple, I can't gather much from the parts fiche on how exactly it's clipped on or even how the two side pieces at either end are attached - and those side pieces are like 30 dollars a pop for some messed up reason so I'm nervous just to yank them off.

BinaryJay

I snaked the passenger side moonroof drain and ran water down it and it seemed to drain fast and exit along the bottom of the rocker panel. Probably should have checked first before snaking so I dunno. I haven't taken the cowl off yet but I ran water down the side drains on the cowl and it seemed to drain freely there as well. Though on the drivers side I noticed a small stream of water exiting down the firewall in the engine compartment from underneath a curved plastic case that had some wires coming out of it... thought that was odd though I don't really know what to think of that yet.

I did find the sensor harness in the cabin by pulling back carpet along the center console in the passenger footwell, and I also pulled some carpet back along the firewall just to see if I could notice any kind of sign of water and I couldn't. The harness didn't seem loose and I'm not sure I could see any way water could even get onto it.

So I'm back to my theory of water soaking the bottom of the engine or splashing up inside either due to huge rain puddles or underbody car wash getting inside a harness in the engine bay but so far I'm not sure where to find the correct harness on that side (if there even is one).

I'm going to test my hypothesis by going through a car wash today without the underbody spray and see if the code returns (it hasn't since the last time I did an underbody wash and cleared it a couple of days later). If water from the top doesn't cause it, then I'll do an underbody wash again and test again - if it happens after that then I will at least know for sure that I am on the right track on water in the engine bay.

Question - is there supposed to be a splash guard under the engine bay? I can see straight through to the ground.

ibidu1

iTrader: (1)

Yes, you should have splash gaurds covering the bottom of the engine. If you are missing a splash gaurd that maybe an issues. Splash gaurd protects the belts and alternator and electronics from splashing up into the engine bay.

If you look under your car and see holes for one then most likely yours is missing.

BinaryJay

So I replaced the cowl today, I pulled the old one off and noticed what may be the smoking gun. Part of the cowl there are two plastic troughs one on the left and one on the right that go underneath the windshield and direct the water that runs down the glass away from the air intake/air filter into the drains. The one on the passenger side that goes over the air filter was missing completely.

I can only assume that during some previous service Lexus had to remove the cowl for some reason and broke the thing off and just went ahead and put the cowl back on without it instead of ordering a new one... UGH. Without that plastic trough piece, water would run down the windshield and go straight down into the cabin along the firewall... with enough water I can see that shorting out the O2 sensor harness which is located right under there.

I have no idea if this will fix it or not yet but it is definitely BAD and I'm glad I caught it at any rate. I can only hope that things aren't rusting to **** under there because of this.

ibidu1

iTrader: (1)

Nice glad you found something that may lead you to solving your issues. Any parts you think may rust you can always spray primer and rubberized undercoating spray

TWong350

iTrader: (8)

Good catch. How's it going now?

BinaryJay

No idea really, no error codes and we've had a good bit of rain the last few days but... prior to my changing the part there were no error codes for a couple of weeks already. I once went a few months between the codes.

My only hope is that water seeping down through the airbox, perhaps running down right along the harness cable was the problem and that it probably takes quite a lot of water before it manifests. I won't really be able to claim victory until say, I get through spring, without re-occurrence.

I'll be happy it's solved (if it is) but at the same time pissed off that I paid Lexus a diagnostic fee for absolutely nothing other than a wild baseless guess about an exhaust leak that doesn't seem to exist.