The CEL came on Right after the 150K mile service, within 5 miles of picking up the RX after the service.
After checking the code, it was a P0430 Code, Catalytic Efficiency.
The Throttle Body was also cleaned, any connection to that?

 

Had a P0430 code at 170K miles jsst after purchasing my RX330 last year, kept coming back after clearing it. I cleaned my MAF, cleaned upper and lower O2 sensors, cleaned throttle body, ran a bottle Seafoam, unplugged the battery to reset the ECM, then gave it an Italian tune-up code has not returned in 4,000 miles plus my MPG rose from 19 - 24. Not sure which of those helped but I'm happy

 

Almost any scan tool can log/graph the fuel trims and the A/F voltage (sensor before cats) and the O2 voltage (sensors after cats) for each bank. Get those then compare to what others have posted for similar issues before spending too much.

I.e., like (there are many more): https://www.clublexus.com/forums/rx-...-confused.html

 

What is an Italian Tune Up?

 

Knowing Italians, it's probably where you rub marinara on all four tires and pee in the fuel tank. XD

 

Italian tune-up = Drive it fast and hard. Get the RPM' s up so it clears carbon and stuff out our Lexus are usually run at low RPM's for extended times

 

In other words, "drive it like you stole it"- I'll try that, Thanks

 

Hi, I replaced the A/F Ratio Sensor on Bank 2 with a Denso 234-9042 A/F Ratio Sensor right after I posted the P0430 Code, and the code has Not returned,
Hopefully it's fixed.

 

Mama mia! Haha

I'm Italian, German, and Irish and I can witness Italians put marinara sauce and cheese on pretty much everything. Haha 😅

 

P0430 the only regular code I get. Changed the O2 sensor (Denso). Still comes on every 200 miles or so (more after hard acceleration especially long periods using EV in slow traffic and I notice driving in the very wet after heavy rain is a trigger).
It is a tiny milli-voltage aberration from the O2 that throws up the code. So, I just zap it off using an OBD diagnostic handheld and keep going. In the UK petrol hybrids aren't tested for emissions in the MOT – and I have had my under-car catalytic converter nicked already (you do however fail if you have a CEL on). There is no change to performance P0430 or not

 

How hard was it to clean the throttle body? was it complicated and hard to get to? I also have had the P0430 for over 20k miles, runs fine but the mileage sucks.

 

Do we win a prize if we guess which car you have or might you help us along by posting which year? The different years have different engines. I believe the P0430 code will kick your car into a more rich run mode hence your hit on MPG

To clean the throttle body on an RX330 it takes maybe 10-30 mins at very most.
#1 - remove the engine cover with an allen wrench (5mm?)
#2 - Remove airbox - (3 or 4 10MM bolts at the bottom) and all connectors/vacuum lines, there will be a couple conenctors you'll need to remove the 10mm nuts from, tough to mess this up easy to remember what goes where
#3 - Use Phillips head or 10mm socket to loosen the clamps holding the tubing to the throttle body,
#4 - Wipe out throttle body with rag and carb cleaner

Complicated? Not in the least it is very straightforward
Hard to get to? Not in the least?
Does it require a high level of mechanical knowledge or special tools? Not at all quite easy.

When retightening the engine cover nuts do not overtighten they are a bit fragile just lightly snug them up.

 

I have the 2004 rx330 (Japanese made) with....are you ready for this???...316k miles. I love this smooth car. Owned it since 274k. Runs well except some squeaky belts..
Thanks!!