Persistent check engine light.
Starting to have problem with transmission.
The RX drives and handles well.
Never has had very good gas mileage.
Starting to worry about transmission.
Bought the RX300 in 2004 with 45000 miles on it and have put 24K on it in the last 2 years. Had no problems until about 6 months ago when the check engine light came on. I figured it was the oxygen sensor since that is the most common cause on everything else I drive. Took it to a local garage, (nearest Lexus dealer is 2 hours away), they said the code was for the left side running lean i.e. the oxygen sensor. They replaced the sensor and the light stayed off... for about 30 seconds. Drove it with the light on for since. Last week my wife said when she pushed on the gas the car would hardly move. She got it home and I drove it to a Lexus specialist here in the area. After having the car for a week they informed me that they had replaced the throttle position sensor and checked 3 other codes that showed up on their computer. They got rid of all but one, the knock sensor. According to them, the sensor is working fine. So I have the car back, but the light is still on. But, they also informed me that while they were test driving the car, they could not get it to shift into OD. Also, they told me that the transmissions are chronic problems on the RX300 and I can expect more problems in the future. So now, after reading all the other comments on this site, I am just a little freaked out. I really don't want to spend 4-5K on a new transmission. I have a 1990 GMC Sierra with 160,000 very hard miles on it and I don't know if the fluid has ever been changed. I don't think a fairly late model car should have the kind of transmission problems that everyone is describing in their reviews. I would probably buy a RX330, but after reading this, I will most likely get some kind of extended warranty.
Your car is fine it's just the knock sensor that is a common but untold design defect on the 1999 RX300.
They actually redesigned the replacement part so it also requires a new wiring harness.
When the knock sensor is bad the check engine light comes on.
There are 2 knock sensors replace them both because labor is the same whether you do 1 or 2 and the parts are cheap.
While the knock sensor is out the computer in the car controls the vehicle fuel mixture and transmission shifting.
It retards the timing and makes the car run rich to protect the engine, also it keeps it from shifting into overdrive.
The dealer charges $900-$1000
When they plug it into the computer to diagnose the check engine light they only get summary info that they must analyze, if you live in a small town then they don't have as much experience with this. I live in San Jose CA where there are 1000's of Lexus cars especially RX300's (very popular here) I found a good local mechanic who did mine for $620 ($170 parts, $450 labor)
Good luck and yes the transmission could go bad (design defect) but it not related to the issue your stating, mine did under warranty also lookout for engine slug issues if the car did not get regular 3,500 mile oil changes.
Thanks for the info. It has been a couple of weeks and I just haven't had time to get the car looked at. I was planning on trailering it to Richmond for the dealer to look at, but I will let the local shop replace the MAF and knock sensors first. I think that I will have them change the transmission oil and clean the filter screen while they have it. I have changed the engine oil every 3000 miles fairly religiously so hopefully I will have no problems with the motor. But I will admit that I have never had the transmission oil changed. My saving grace may be that we live in an area where there is not much stop and go driving and my wife's work is only 5-10 minutes away. So the transmission oil shouldn't have much opportunity to get really hot. The fact that the transmission seems to have some kind of manufacturing defect doesn't do much for my confidence in the car. Especially since it is out of warranty. I anticipate that if we can get it straightened out we will trade it in on something else in the near future.
Update from the original author. Took the car to the shop again and had the knock sensors and the mass air flow sensors changed. It seems to have cured the no overdrive problem and for the first time in quite a while, the check engine light is not on. I also had the transmission oil changed and the filter screen cleaned. They said that the oil was not that bad. Just a little off pink in color. I would have to say that this is the first time the oil has been changed since new and we have right at 70,000 miles on it. He did say that he would recommend having the transmission oil changed again at 80k. The cost of having the 3 sensors replaced and the transmission oil changed was $732. Much better than the 4100 for the new transmission. I had talked to the dealership about the problems I was having and they immediately said new transmission. I am curious to know if they would have actually replaced the transmission without first replacing the sensors in the motor. If so, I would have gotten a new transmission that would still not shift into overdrive. Hopefully everything is OK now. I will update in the future.
Me2 in a "no overdrive" situation with CEL on.
Mine is a AWD RX300 2000 has about 61K on it.
The check engine is on for couple of months. Since I didn't notice any deference while driving, I just leave it as is. About two weeks ago, I noticed high RPM at 45-60 MPH, then noticed that it is not shifting to overdrive.
I took it to autozone, got the code p0171 and p0330.I have the trany flushed ($200), cleaned the MAF ($2, DIY). Now the p0171 is gone, but p0330 still there and it is still not shifting to overdrive. I also feel it is luck of power and MPG drops from 17 to about 14 or 15.
So what's the next?Replacing the knock sensor?
Anyone can tell me which cable is the one connect to the knock sensor?I would like to check it myself first since accroding to the dealer, it is rare to see some bad knock sensors...
According to my local Lexus shop, there were some defective knock sensors on the RX's. The new knock sensors have been fixed and also require a different wiring harness. We have put a couple thousand miles on the RX since being fixed and have had no more problems with overdrive or CEL. There are 2 knock sensors and it is probably wise to replace them both while you are at it. Good luck.
I just spent $4k for a rebuilt tranny on my 2000 lexus rx 300, two weeks later I have a proplem with the overdrive. This car has been a nightmare.
I recently had a catastrophic transmission failure on the highway - the same problem reported over, and over again for the Rx300 (bought it in 2000 new). The same part goes out each time - the front fluid pump. Lexus refuses to acknowledge the problem, much like the oil gel problem. Another class action settlement is the answer.
Can you please tell me where in San Jose your mechanic is? I have some maintenance coming up for my RX 300 and the dealer prices are horrific.
Our transmission pump went out on '99 Lexus RS300. Dealer is indicating need whole new (acutally rebuilt) transmission for $4800. But no engine light came on and didn't drive car but about 20 miles after we noticed engine noise. Can't we just have the pump replaced?
Mine is 1999 RX 300 with 186K miles. I suddenly noticed the CEL on and at the same time no overdrive. Checked fluids, looks OK and pink. Knock senser maybe?
Is there any possibility that the warranty will cover this "knock sensor" thing? My check engine light came on yesterday and I'm wondering if it would be covered?
Hi Guys, I was planning to get one of those RX300 1999 model. Since keep reading and reading more comments it feels like I am starting to go away with that car (RX300). I think for a 8 years RX 300 is no longer recomended eyhh? what you think guy's? As far as I can tell from those comments, most problem is transmission. thanks for keep posting.
I have a 1999 RX300. When I first saw the car, I immediately fell in love with it. I love driving it and felt comfortable. I maintained it pretty well with proper documentations as well. I drive at least 30 miles on the freeway almost everyday. Until one day, the engine light (CEL) appeared. It was on for almost 2 days, until I hit the brakes harder than usual, and the light disappeared. The next day, as I was driving on the freeway, my speed-o-meter is on 65-70, but I was pressing the gas pedal harder than ever... it was running like at 40 - 45 mph. I brought my RX300 to my mechanic. He changed the oil (synthetic), changed the transmission fluid. Then 2 weeks later, I went back to clean and change the transmission fluid again (per his advise). Then 2 weeks later, when I started the car, the noise was not normal and as I drove the car, this weird noise (like a small airplane about to land) and it was not accelarating... the speed was going slower and slower even though the speed-o-meter indicated 65-70 mph. So I brought back to my mechanic again... this time he said it has transmission pump problem (per the noise he heard). The 2 visits I had, my mechanic charged me about $175 each visit. This time he said to change the transmission pump, it will cost roughly about $1500. Oh boy.. what's next! As much as I love RX300, I do not like spending $$$ on car repairs. I have this belief that once a car starts acting up, it will happen again and again.
Do you think this "transmission" problem should be brought to the attention of the LEXUS manufacturer?? Thanks.
1999 RX300
Intermittent CEL? Maybe no OD when CEL on? Check the knock sensor. NOT a transmission problem!
I had an intermittent CEL for 2 years, usually could get it on after 1-2hrs of interstate driving, the hotter the day the better the chance. OD might not engage while CEL on, it too very intermittent. CEL might reset after a couple seemingly cool nights. Actually no big deal. Could force the OD shift by staying at speed, shifting into N, shut off engine, restart, and reengage D. Worked every time OD failed to engage with the CEL on. Finally decided to have it looked at. Lexus dealer replaced both knock senders. $1,100US. All fine now... Go figure, but not a tranny problem!
I have been seeking a used 1999 RX300 for since 7/6/07. I have gone through 2 vehicle inspections on these cars. They keep coming up with transmisiion problems. Buyer beware. This has only cost me $300. I'm on to a different vehicle. Thank you for this form.