APN

My wife's 2000 AWD RX300 runs just fine on 89 octane. The only concession I make to the fuel system is to add a bottle of generic fuel injector cleaner to the tank at every oil and filter change. That's been a habit of mine for decades across many different vehicles, and I've never had one knock or ping.

Keep in mind that different areas of the country require different fuel formulas at different times of the year. You might have to do some experimenting before you find a solution that works for you.

You may also want to pull a couple of your more easily-accessible spark plugs (the three front ones) and ensure that you indeed have the iridium spark plugs from either NGK or Nippondenso as called for in your owner's manual. They truly are a requirement for this engine to operate at peak efficiency, and they are rated to go 120,000 miles in this vehicle. At about $10 apiece from NAPA or a similar auto parts store, they're expensive but mandatory.

Hi

My wife has a 99 AWD RX300, we use 87 octane from the start with no problem. Last few days she told me, and I confirmed, about a rattling noise coming from th eengine when the car is revved to around 1800RPM, above and below that it has no noise. Does anyone have any advise as to where I can look for the source of this noise. The noise sound like metal tapping at fast rate.

Also can the spark plugs be changed at home or one has to bring the car to the shop for special tools ?

Thanks.

I have had my MIL coming on a couple of times, every time it is the same, P171 I think, Bank one running lean. This only happens when I go from my elevation 7500 to sea level, could this be it?

You should clean the MAF first. it is easy and almost no cost.

Lexus/Toyota timing belts have a solid reputation in the automotive industry. They are thicker and wider than many other Japanese automakers.. My RX owners manual calls for a timing belt change at 90,000 miles, but I've had two different and unaffiliated Lexus service managers tell me that they rarely see timing belt failures before 120,000 miles.

To be safe, I think 120,000 miles is the furthest extent you should push for. Change it soon and sleep better because of doing so.

riwyle is correct - no engine damage will occur if your timing belt fails while you're on the road. So if you're willing to roll the dice, keep on driving with your original belt. If we still own our RX at 120,000 miles, I plan to change it then.

My local Lexus wants $1100 to replace timing belt, water pump and spark plugs. How do I know if I really need to repalce the pump ? Do you know how to repalce the plugs ? It is npot much but I jsut want to know to replace spark plugs at least. Thanks.

I too feel like I'm burning thru more gas. I put 87. 99RXAWD bought new, now w/65k mi

I think cleaning the MAF is easy and quick enough, it doesn't hurt. I removed the 2 scews and took the MAF sensor off the air filter housing, used a Q tip dampened with contact cleaner to clean the visible metal contact and the tiny wire sensor located at the top of the sensor housing (looking up from the bottom of the sensor). Then I gently dried off the cleaned parts using canned compressed air. Ten minutes job. Reset the CEL and it has not returned for few days now; engine knocking is gone. I could see the black deposit removed from the sensor parts on the Q-tip.

BTW, can anyone show me how to replace the spark plugs on the RX300.

Thanks to everyone for your advise with my CEL issue.

APN,

The dealer replaced our Bank 1 Sensor (the one near the firewall) in August using their "goodwill" warranty extension. This sensor failed at about 68,000 miles. Both trouble codes pointed to this particular sensor, and its replacement fixed this particular problem on my wife's RX.

No, I never cleaned the Mass Air Flow Sensor because the trouble codes did not point to it. Plus, our Mass Air Flow Sensor failed last October and was replaced by the dealer under regular warranty at about 48,000 miles. Damn these multiple lousy sensor components - I've never had an oxygen sensor fail at less than 120,000 miles on any of my other vehicles, and we've had at least a dozen different vehicles (none of them either Lexus or Toyota) since oxygen sensors first came into widespread usage on vehicles in the mid-1980s.

Other RX owners on this forum have described how they cleaned their Mass Air Flow Sensors as part of their troubleshooting process. It typically involves using a can of throttle body cleaner spray as well as a can of compressed air. Check the forum threads from this past July and August and you'll see some excellent details of just how several folks went about doing this. In a couple of cases, cleaning this sensor fixed that individual's particular problem. But you have to take your time, use the cleaning products carefully, and be sure not to oversaturate the sensor components with the cleaner fluid. The canned air assists in creating rapid evaporation of the cleaner fluid so oversaturation is avoided.

Keep in mind that if your particular trouble codes don't point to the Mass Air Flow Sensor, you're probably not going to succeed in turning off your "Check Engine" light on your dashboard by cleaning it.

Thank you for your time. I will do that and report back to everyone.

RX in NC,

Thank you for the head up with various sensors problems. So far I was able to clean the IACV and the MAF. No more engine check light for now, but I'm sure I will run into your problem soon (my rx300 is at 73K miles). Please keep us update with what dealer replaced on your rx300.

OLDRX300 :

How did you clean the MAF, can you please share ? I replaced my A/F sensor (bank1) but still have the error (P0171 - system too lean bank 1). My next step is the cleaning the MAF.

I also found and fixed the problem with clock reset when engine is started if anyone interested.

Thanks

APN

A couple of other common RX failures involve the exhaust manifold and the multiple oxygen sensors on this vehicle.

The exhaust manifold has a tendency to crack so have it checked for leaks.  If you find that yours is indeed cracked, it is a warranty issue and your Lexus dealer will replace it at no charge.

The multiple oxygen sensors tend to begin failing early, sometimes at less than 50,000 miles.  You'll see a "check engine" light illuminate on your dashboard, and your best bet at that point is to go to your nearest AutoZone where they will plug in their code reader and determine your trouble code at no charge to you.  The trouble code can then be cross-checked to inform you what's wrong.  It's usually one of the sensors.  Lexus charges extreme amounts of money for these little devices, but you can usually save yourself quite a bit by going to www.oxygensensors.com and ordering them yourself.

Good luck with your RX.  This site has provided me with numerous RX maintenance tips and tricks over the past year.  That has enabled me to save significant money in maintaining my wife's RX myself.  She likes the vehicle but I don't and since I'm the one who must work on it, we won't be buying another one after she wears this one out.  Just too many flaws and they're overpriced and underpowered.

RX in NC

You are very knowledgable on this RX300 subject. I had the CEL on my wife's 99 RX300 (84k miles), Autozone read code P0171 (System too lean Bank 1), other discussion pointed me to the Air Fuel ratio sensor. I learned that bank 1 sensor is the one closer to the firewall. I could loosen the mine, fearing breakage I brought it to the local shop (Honest Engine) to have them remove it. They didn't do anyhting special other than forced it out, part of the thread came with the sensor and they made me pay for it claiming that Lexus must have crossed treaded putting it in. So I was out over $1100 for the manifold, gasket, sensor and labor. AND now I still have the same error. Unbelievable !

Can you please tell me which sensor the dealer replaced on your wife's car ? Bank 1 (near firewall) or bank 2 (near radiator). I will never to back to Honest Engine again and cannot afford to feed the dealer at this point. Did you ever clean the Mass Air Flow sensor ? How did you do that ?

(I will not buy another RX either)

Thanks

APN

I don't know if you received my email or not.    But these are your problem.  Check your Mass air flow sensor and A/F bank 1 sensor 1(by the firewall). 

-Mass air flow sensor:  this devices measure how much air going through your engine.  If it doesn't work, it would cause your engine to run lean.  And cause the knock. 

-A/F sensor:  Air/fuel sensor, this unit located on the exhuast manifold.  It will provide the ECM with air/fuel going through the exhuast. 

My bet is the A/F sensor but I don 't have the vehicle with me So i couldn't properly diagnost. 

                JP IMPORTZ

Hello,

On my 99 RX300 (84k miles) I had code P0171, I could loosen the sensor and the local shop replaced the bank 1 A/F sensor but the same error appear again . Can you please give more direction.

Thanks

APNRX300

This is a common problem. When you replace the ignition switch you will need to replace your keys and locks. This is no fun. They were nice to cover the parts for you. Otherwise it will run about $1100 for the ignition key and lock set. Good luck.

JPI

Hi

In my 1999 RX300 I removed (effortlessly, no force) the key in the ACC position. Stuck it back in and could not turn to LOCK or START. I towed the car the dealer and they recommended to replace the lock cylinder and keys (inside parts nto whole keys) for abotu $1100. I screamed and the service guy offer to replace the lock cylinder only for about half the price, although it is not what Lexus would recommend ! He was honest by saying that he had done this "unrecommended" reapir for those who wanted to save $500 and "none came back".

Can someone help me with my questions :

1. Did I damage the lock ignition ?

2. Did I make the right decision by jsut replacing the lock cylinder ? If it doesn't work, I would have to go through the whole replacing the lock cylinder and keys not just adding the keys (WHY ?)

Your explanation would be really appreciated.

APN :cries: