Jadedpanth

So, I originally took my 99 rx300 to a Midas, who told me that all 4 of my oxygen sensors were out...at the same time. Being the researcher that I am, I told him that I only have 3 and that he was either trying to screw me or didn't know enough to fix my car.

So now I'm trying to do some repairs myself. According to my diagnostic at both midas and autozone, I need a new thermostat (which doesn't seem too hard to do). Question is, should I try and buy the part new from lexus? Or will an OE brand do? Also, I've heard conflicting reports about what type of antifreeze I should use (doing a radiator flush). The guy at the auto parts store said to go synthetic...what do you all use?

As for the O2 sensor, it turns out that only my front O2 sensors are out, my rear one is fine. Has anyone tried changing an O2 sensor? My boyfriend did what he thought was the easiest one (bank 1, sensor 1) and it took 2 days. Not going down that road again. So I'll probably have to have a shop do it. We used a bosch originally, but the guy I called at Firestone said that you should only ever use lexus parts for an oxygen sensor, anything else will fail in 6 months. What do you all think? I know this is a lot and I appreciate any and all responses.

~Jade

lexus114

Well jade,you have two air flow sensors,and a post cat.02 sensor. I would recommend only using the original equipment Denso parts. Is your tempeture guage showing to cold? I don`t know if your thermostat is bad,it may be a temp. sensor failure. As far as antifreeze,go with the Toyota red coolant (the one that is not pre-mixed)
Ryan

Lexmex

Welcome to the Club.

1. Were their OBD2 codes that they pulled and if so what were they? If you don't have them, I am sure Autozone will bring them up again and you can tell us what they were.

2. Before you go out and buy a thermostat, what exactly did they tell you at Midas/Autozone? I have a hunch it was a P0125 code, but that doesn't mean there a thermostat issue. That's a code that often pops up when there is an A/F sensor (term is used interchangeably with O2 sensors). After 15 minutes with the motor on, where is the temperature gauge on the dash. Since now I am back at sea level (and this is an old story), I now run 50% Toyota Red Coolant and 50% water, plus I throw in at least one bottle of Royal Purple Purple Ice coolant additive.

3. I haven't had the luxury of changing the sensors in my vehicle (how fortunate despite all that awful gas I ran in Mexico). Bank 1, Sensor 1 would actually be behind the motor (I congratulate him immensely if he did this one) with Bank 2, Sensor 1 being the one when you open up the hood by the radiator. Only sensor I recommend is the original Denso sensor. We have had some issue with people using Bosch sensors and also those from Walker. Not saying that it couldn't work, but I have seen too many times where it didn't pan out.

Above all, let us know what codes were found.

Jadedpanth

Thank you so much for the quick responses. Here's an update, which makes me hate large chain auto repair shops.

So I happened to see an ad, while I was at firestone, for a japanese auto repair shop (newspaper). I called them this morning and spoke to a very nice gentleman. I read him all of the codes Autozone gave me (P0171, P0125, P0300, P0301, P0303, P0305) and he said it didn't even sound like I needed a new thermostat or O2 sensor...he said it was more than like an air/fuel sensor problem. Also, something called a mass air sensor (something like that, I may have gotten the name wrong). Anyway...this pissed me off that I even spent 90 dollars at firestone getting a diagnostic, which has largely seemed to be wrong.

I called firestone and asked them if they changed my O2 sensor and that wasnt the problem, would they charge me to fix the air/flow sensor. They said no. Now I don't know what to do. Go to firestone and maybe have them give me a free O2 sensor if they are wrong? Or go to this other company and pay 700 for new air/flow sensors? What would you all do?

Lexmex

I'll try to point you in the right direction and it's called an ignition coil and goes on top of the spark plugs. I don't know offhand if you also have a MAF problem (we'll get to that). However. The ignition coils in question are located behind the intake manifold. P0301- is related to the rear coil most to the left, P0303, the one in the rear middle and P0305 in the rear right. Conversely, 2, 4 and 6 would be on the front. See photo below.

You need only a 10mm wrench (I'll show a photo of that) to remove these. You don't need to remove the engine cover to get to the rear ones (will show a photo, too).

Do you notice that the engine is bogged down when you accelerate, because that's usually what occurs when you have an engine misfire (which is what those codes are related to). Sometimes you can get bad fuel. My girlfriend has a Ford Expedition that had such an issue until I switched her over to Chevron from some generic gasolines around here.

Jadedpanth

I'll tell you what, it better not be a coil issue, considering that I had all 6 of them replaced (another necessary thing from midas). I really wish I'd found this forum sooner. I know I've wasted about 2K on this car in the last year.

Lexmex

Okay, that saves me some photos. But do you know what kind of coils they put on there, that might be part of the issue. Other things that could make it go bust would be some bad gas.

The MAF sensor issue can be looked at here, https://www.clublexus.com/forums/rx3...out-yours.html starting at post 7 to see if there is any accumulation on the sensor itself.

Do you feel that the vehicle is bogged down when you drive it?

Did they also change the spark plugs, too?

Jadedpanth

I did have some weird driving issues last week that have since, gone away. My car wouldnt shift gears at first...it would drive very slowly (despite pressing on the acceleration) and them suddenly get faster (I think I've heard it described as a "slingshot" effect). However, since it rained a week ago, my car's been fine. Not sure if one has anything to do with the other.

Not sure about the coils...the reason I got those replaced was because my engine was literally shaking and my engine light was red. Totally freaked me out. I don't believe my spark plugs were replaced, but I've heard that's an easy fix I could do.

As for fuel, I always fill it with premium 93, but I really don't know anything else about what kind it is. Also, I just put some fuel injector in there...so hopefully that helps.

Lexmex

Do you have a check engine light on now?

Jadedpanth

yes, it is still on.

Lexmex

When was the last time you had the codes checked?

The reason I am saying this is that the misfire codes might no longer be in there (or they may very well be in there).

Moreover, unless you're handy and you want to try it yourself. I would actually take, upon confirmation that the misfire codes are still in the computer, the rear ignition coils and stick them on the front (1,3,5 coils to where 2,4,6 coils are and vice-versa). I'd still be interested to see what type of ignition coils were put in there. I've been able to put a Camry coil in there albeit slightly modified that did the job, but that was a Denso coil. I know there are a few other companies that make an aftermarket coil for the RX300, airtex, acdelco, standard motor products, but just like oxygen sensors, I'd stick to the original Denso ignition coils (regardless of the cost).

Jadedpanth

The codes were checked on Dec 26. I'll call midas and find out about which coils were used. I'll try the MAF cleaning...hopefully it helps as well.

lexus114

Your check engine light was red?

Jadedpanth

I thought so...though I may have been in shock at the time.

Lexmex

This is the kind of coil that should be in there.