Help! 2006 RX330: CEL, VSC and TRAC OFF lights on

[softeject70]

Greetings Folks: 

Over a week ago we brought our ’06 RX330 in for service to replace a fitting on the engine that had been leaking coolant, eventually causing overheating. 

We got it back a day later, and it ran fine. However, this past Tuesday, the CEL (Check Engine Light), VSC and TRAC OFF lights came on, all at the same time, and have remained lit since. 

I dug on the internet to find some solutions and/or troubleshooting, and was met with quite a bit of information. However, I wanted to ask any RX330 owners here if they have experienced the same thing. 

In the meantime, I took the following troubleshooting steps:

1. I checked the fuel cap to make sure it wasn’t loose. As a further safeguard, I bought a new one ($15) and put it on. CEL remained on, as did the VSC and TRAC OFF. 

2. I went to Pep Boys to have them scan and pull a code. It read P0420: (Catalyst System Efficiency Below Threshold (Bank 1)). Now, this same site lists a whole series of tests to perform before heading out and laying down some $$$ for a new cat. So I’ve decided to go through a few of them:

3. I took the car for a test drive and listened for any inconsistencies and/or rough idling, etc. I found none, and engine was running smoothly between 1-2K RPM as usual. 

4. I bought some fuel injection cleaner, fuel cleaner, and a can of MAF Sensor cleaner just in case. Right now I’m at a little under half a tank of 87 gas, so I’m going to wait until it’s under a quarter tank and pour in a bottle of the fuel cleaner or CataClean and see what happens.

5. Today I’m going to check the air filter and possibly the spark plugs if I have time, to see if they’re all mucked up. I guess that’s the best time to clean the MAF sensor as well. 

So, that’s my process so far. Is there anything else I should take a look at? I’ve heard about checking and/or replacing O2 sensors but not sure if that’s really the issue here, but would love to hear your input. 

Thanks for listening, and would love to hear your feedback.

[TrevC]

Hi Greg,

Where was the replacement fitting located (in the engine bay) and could you find out what was removed to fit it, as sometimes its easy to dislodge a sensor connection?

An exhaust leak is also possible if it has raised an issue with the Cat.

Cheers  Trevor

[softeject70]

Hi Trevor: 

Thanks for your input. 

I believe it was the Factory Water Inlet Pipe, as seen on this Ebay listing. 

According to the mechanic (whom I've visited a few times before), it was a common piece that needed replacing on the Lexus RX330s. It was definitely leaking coolant around that area, and the flexible rubber hose attached to it seemed to be in decent shape. It hasn't overheated since, so I suppose all is well in that aspect. 

Something else comes to mind—I also asked them to change the oil. I've read in other forums that sometimes during an oil change, a certain hose can get dislodged from the air filter housing, causing sensor errors. I'm just not sure which one it would be. The visible, skinny hoses all appear to be in place. Then I've also heard there  is one underneath the air filter assembly that can be dislodged…is there such a thing?

By the way, as an update to my adventure, I dropped in a bottle of CataClean as I've heard that stuff works wonders. I did it according to the directions, pouring the entire contents into the tank when it was 1/4 full, then drove about 15-18 miles before refueling with 91 instead of the usual 87. I know it's been less than 50 miles since, but 3 lights still on. 

I'm beginning to suspect that maybe a dislodged sensor or hose due to the service could be to blame, but I haven't had time yet to investigate thoroughly. Perhaps this weekend. I can also check beneath the car for exhaust leaks, but being around the car, even around the tailpipe, I haven't noticed or smelled anything unusual. 

Again, your thoughts and suggestions are appreciated. Thanks!

Yours,

Greg

 

 

[TrevC]

There is usually a hose on the underside of the air cleaner assembly to allow crankcase vapour to be recirculated, so worth checking if you can access the area.

Good luck with the checks and let us know how you get on

[softeject70]

Thanks Trevor. I'll check that out this weekend.

Btw, still no change after using Cataclean. 3 lights still on. 

I wish I took a better look at that scanner that they used at Pep Boys. The only error code I could read was P0420 and "02/02," which I couldn't decipher. 

The other thing I've read about was to change the O2 sensors after the catalytic converter. There are two of them, correct? Does anyone know the part numbers on those? I found the "right" one on Autozone, which goes for about $100...

http://www.autozone.com/emission-control-and-exhaust/oxygen-sensor/bosch-oxygen-sensor/596751_972614_1784/?checkfit=true

Has anyone done this type of repair? Is it difficult to do?

Thanks again for your help!

 

[softeject70]

Update:

In hopes of clarifying the situation, I brought the SUV back to the mechanic who had serviced it before, to have them run codes on their scanner. This time it read clearly, "P0420 B1." As I suspected, the mechanic said right away it was a bad cat. "That's a very common error code we get all the time," he said. "You need a new cat."

I asked him if there was a possibility that the downstream O2 sensor could be at fault. "No," he replied, "'Coz there's a specific error code for a bad O2 sensor." 

He quoted me $1200–$1300 for a new cat, which is way beyond my means right now. Besides, that sounds really steep. What do you guys think? 

BUT—Here's the good part, unless I'm mistaken. Before he unplugged the scanner he asked me if I wanted to clear codes. So I said yes, and all 3 lights disappeared. He chuckled and said, "Let's hope they don't go back on." 

So far we've taken it out around town all weekend, on both streets and freeways, without a blink. Could this mean that my CataClean and 91 gas did the job, or should I look into swapping out that O2 sensor (Bank 1?) after all?

I'm due for tags in November, but I'm thinking about doing the smog check this week while the lights are out, just to see. Any thoughts?

[softeject70]

UPDATE: 

Since my last post back in September, I'd been running the RX330 on 91 octane gas and diligently keeping my eyes on the dash for any of those 3 lights to turn on. 

Luckily, they never turned back on! 

So, a few days ago I took it to the local Rocket Smog for a smog check, as this month, as previously stated, my tags are due. I crossed my fingers, and I passed! 

*whew*  ...well, I guess I'm good for now...

 

[softeject70]

UPDATE:

Happy New Year Folks: 

Well, I'm back. Wife said the warning lights came back on today. Brought it back to Pep Boys for another error code read, and it read the same: P0420 P 02/02. 

I had them reset the codes and I put a bottle of Cataclean back into the tank. I've driven less than 5 miles but so far, all clear. 

My only other concern is that I've had a "MAINT REQD" light on for awhile (a few weeks to a month at most). The car seems to be running fine, so I haven't addressed it yet. 

[softeject70]

UPDATE: 

So...CataClean strikes again. Drove from LA to Las Vegas over the weekend without incident. 

Btw, in another thread, someone posted a scan from the owner's manual on how to get rid of the MAINT REQD signal by holding the odometer button down while putting the key to the "ON" position...tried that several times but didn't work...any thoughts?

 

[sawotka]

Hello , I just reset mine actually. That does sound correct it took me a couple attempts ..The procedure is in your owners manual.  

[softeject70]

I finally found the procedure by looking again online. It was slightly different than what I was doing, but I got it to work. No more MAINT REQD light =)

I'll be sure to keep you all updated on my situation. Thanks!