renfaiz

2000 Lexus RX300.

The check engine light started flashing today. The engine is running rough, more so at lower RPM, smoother at higher RPM. Almost no power at idle and very low RPM, but more power at higher revs. The car will not shift into OD. I figured this a sensor gone bad.

Within about 1/2 hour, it then developed a loud exhaust sound from the engine compartment, on the driver's side. So, now I am guessing that it's an exhaust gas sensor that fell out, leaving a hole in the exhaust, somewhere close to, or actually in, the engine compartment. I have not yet been able to locate this sensor just by raising the hood and looking around. I don't know where to look.

I would rather replace a simple sensor myself, than have a shop or dealer charge me a fat fee for installing and overcharging me for the part, as well. Does anyone know where, on the engine and exhaust system I should look, and/or how I should access the right place to look, and what I should look for?

Also, though I've worked on other cars in the past, this will be the first time I will work on this car myself. Does anyone have preferences for particular online parts suppliers, or against any, and your experience or reasons?

Thanks very much

Ren

*somebody posted something in the left column, about "garage" that I did not post or request be posted*

code58

Ren- you should be able to run it with the hood up ,and be able to tell about where the loud noise is coming from. I have never heard of a sensor falling out, most of the time you have a hard time getting them out. LOL
I believe everybody gets the 'garage" in the left top of the post, most people just don't bother to put anything in their "garage"

mikey00

Sounds like you have an exhaust leak. That's assuming it is an exhaust noise you hear. This causes the sensor to get a bad reading and turns on the check engine light. When the CEL is on (for some codes) the ECU will prevent the trans from shifting into OD. Just look for the exhaust leak like on any other car. Some trouble spots near the engine on 2000 RX are crack in rear exhaust manifold or failure of the flex joint below. If the sound is more under the drivers side door check the spring clamp and gasket located on the exhaust pipe in that area.

Lexmex

Welcome to the Club.

First, don't worry about the My Garage feature, that's if you want to do that, but it shows up for everyone and can be used if you want to tell us more about your vehicle.

Those symptoms appear to be a misfire of one or more of one of the ignition coils. A flashing CEL is a sign of that along with the issues you mentioned occurring with your vehicle, but you'd need to get a code reader to ascertain this. You can fix the coil yourself (provided you get a replacement). That extra gas going past the combustion area could have caused an issue downstream (exhaust noise).

I wouldn't drive the vehicle, but I'd have to 100% ask that you get an OBD2 scanner or get in contact with somebody that does (they are available for under $100 and virtually every mechanic I know has one, including my uncle back in Mexico). It's really going to poinpoint the trouble area. You bring us the codes and we'll try to help as best we can.

Now, if you want to see possible areas along the exhaust system where there might be an issue, I wll post photos below of areas.

Lexmex

Bank 2 Sensor 1, A/F sensor

Right in front of the engine block and behind the radiator, you can't miss this one.

Lexmex

Bank 1, Sensor 1 A/F Sensor, this is behind the engine block, so you will have to crawl under.

Lexmex

O2 Sensor, this is after the catalytic converter beneath the vehicle. Sensor visible from driver's side.

Lexmex

Another area for noise is this exhaust area right beneath the engine block. Before I replaced the piping, my uncle ended up welding this area at least two times to seal it shut.

Lexmex

Another area of issue is in front of the catalytic converter at this junction and the exhaust gasket can go bad. It's just to the left of where he is cutting.

Lexmex

However, I think the root cause of the original issue started with one of these ignition coils going bad.

renfaiz

Hello LEMEX,

Hey, thanks for all this. Amazing, all these pictures and info. You work on Lexus for a living? I'll have to read this over a few times, and try to understand everything, then I'll post again.

I did drive the car yesterday, despite this problem. To begin with, I was 40 miles from home when it happened, then later I had things to do and no way to go get a rental.

I'll check along the exhaust system, as best I can, to see if I can locate anything obvious. I live about 40 miles from San Diego, am retired military and am able to use the auto hobby shops on the military bases. So, all the tools are there, but I have to drive that far and hope I can get it fixed in one trip. If I can't locate the problem by doing that, I'll probably have to take the car to the dealer or some independent repair shop, since I don't know anyone who has the tools and test equipment, other than what I mentioned.

Thanks again for all your info and all those pictures. You're a Lexus lexicon.

renfaiz

Ignition coils?

I need to learn about this. I'm guessing there are separate coils, one for each cylinder. How much has to be dismantled, in order to get to them?

Less than 18 months ago, I had two sensors replaced, that were supposedly way in the back, inside tons of other bolt-on engine parts. The computer indicated they were bad, and the car wouldn't shift into OD then, either. That refusal to shift was the only indication of a problem, at that time, and the engine ran ok. I was hundreds of miles from home at that time, visiting in Las Vegas. Lexus was booked up for a month, so I took the car to a Toyota dealer who said they could fix it in 1/2 day. Since they had to dismantle so much, I had them replace the plugs and, while it was in the shop, do the front brakes.

A couple of months after I got back home, the front brakes began to squeal, worse than anything I've ever experienced. I think they put cheap-junk brake parts, or at least the wrong pads, on the car.

Now that you mention an ignition coil, I'm thinking that something also wasn't done right when the plugs were replaced. (I have a tendencey not to trust dealers, so that might be my paranoia talking)

I'll look into this.

Thanks again, LEMEX

Lexmex

Take a look at this thread and throughout it they will show the location of the ignition coils (3 on the front and 3 on the back), https://www.clublexus.com/forums/rx-...-patience.html

An OBD2 scanner tool should be able to easily give you the code, P030X (with x being the cylinder number). Cylinders 1, 3 and 5 are the rear cylinders going from passenger side to driver's side, and cylinders 2, 4 and 6 are the front cylinders going from passenger side to driver's side.

I have had a coil go bad on me when I lived in Mexico and had to modify a Camry coil until I could get an RX300 coil from the U.S.

Those sensors you mention that affected your overdrive sound like knock sensors.