Joined: Jan 2018

Posts: 1

Likes: 0

From: CA

Hi there,

I have a 14-year-old Lexus RX330, which has been running smoothly up until now.

1st event: mechanical grinding noise and vibration.

Parked on a gentle-sloped uphill driveway, on a rainy night. The noise and vibration happened when backed off the driveway. Initially thought my car was scratching badly against the rock retaining wall. Came out and checked surroundings, not the case at all. Changed to forward “D” gear, happened again. Shut the engine down. Restarted the engine. Same problem - noise and vibration in both directions. The commotion seemed coming from the bottom center of the car, not from the hood. After the 3rd or 4th try of restarting the engine, the issue happened with only the backward “R” direction but not with forward “D”. Since I was merely a half-car distance away from the main road, I backed the car in “R” with that noise & vibration on anyway, then switched to “D” and drove home. My home is about 8 miles away and there was no issue in the “D” gear on the way home. Once at home, I tried the “R” gear, the problem was gone. I couldn’t repro it in either direction ever since.

2nd event: a month later, the “check engine” and “VSC” lights turned on.

Husband tried “tighten the gas tank seal”, “change air filter”, to no avail. Reset the lights, but after some miles, the lights always came back. Bought tool to read the code, it says the faulty component is "P0420 Catalyst System Efficiency Below Threshold Bank 1". Diagnostic pictures are attached below.

Questions:
1. Are these two events related?
2. Wondering whether replacing the catalyst converter ($1000 cost) would fix the problem or not?

Did anybody have a similar experience before? What do you think could be wrong here?

Your input will be highly appreciated!

Joined: Aug 2002

Posts: 607

Likes: 84

From: Colorado, USA