Lexus RX 400h Engine Problems

mkkidmkkid Member Posts: 11
Since day one (now got 8000 miles) I often get a stuttering or engine miss feeling at steady 30-40 mph. This problem isn't constant, but it does bother me. Anyone else experience this?


  • chops57chops57 Member Posts: 5
    I just got my 400h last weekend. When I test drove it, the engine was as still and quiet as could be at startup when still in the "park" position. Now that I have it in my garage, I am noticing different behavior. When I turn the key position, it is completely still at first for about 3 seconds. After that, I will still be in the 'park" position, but it will feel like the engine has come to life and I actually feel it running, like I would feel the engine of a non hybrid car. Is this normal?
  • katzjamrkatzjamr Member Posts: 146
    This is completely normal. The 400h will start up during a cold start to circulate oil, to get the catalytic converter up to temp, to provide heat on cold days or to charge the battery when it is low. This can happen at any time, but it will always fire up when on a cold start. It feels like the engine in a non hybrid car because that is exactly what is running. It is alittle louder on first start up then quieter when warm. Enjoy your 4ooh.
  • lexus400lexus400 Member Posts: 8
    I had this problem with less than 1000 miles and returned to dealer. They test drove the car and said that if many others were having this problem they would work on solution via software reconfiguration. At 5000 miles, the service manager, district manager, dealer tech have all driven and MAYBE admit that there is a problem. They finally called engineers and said that there is a patch coming out-strange that I am the only one who MAYBE feels it but they are working as we speak on a patch. My issue is a stuttering/pulsing at 37-42 mph and I find it quite annoying. They have asked me to wait and see if the issue is resolved via software fix. Don't know what choice I have now after spending 52,000K on this car and hoping that it would have great gas mileage-which is not close to quote-and feeling good about the hybrid aspects for the economy on my pocket and the environmental impact that I would be contributing to with this purchase. I would love to know if others are having this issue. They are saying that some people are more sensitive than others so I would love to hear from you if you are having the same issue.
  • mkkidmkkid Member Posts: 11
    There's some degree of comfort knowing "others" experience this problem. I've simply "put up with it" but with your info, will push my dealer into action (if that's possible.)
    Mine is a problem that occurs in same speed range as yours and probably happens 30-40 percent of time time. None of the gauges (mpg, etc) show any corresponding "fluttering" when the engine pulsing happens.
  • mkkidmkkid Member Posts: 11
    Following up on my previous response to you, I first called Lexus tech support people to see if any service bulletins, etc. had come out on this stuttering problem. They could find NOTHING. Then I called my Lexus dealer service expert and he had no idea what I was describing much less a solution offering only to do a "road test."
    If you ever find a solution, pls respond.
  • lexus400lexus400 Member Posts: 8
    As of now they are calling it a nibble and say that they are in the process of a computer patch that will fix the issue. After driving my car 500 miles, I was sure that it was a tire issue. They assured me that it was not. The service man said that he felt the pulsing. Later I had to return for the service manager to test drive-he couldn't feel it he said. Later I had to return to have the district manager drive it. He said that he couldn't feel it, and said that I was the only one with the issue. Yet I then heard that they had a lady with the same issue in several hours earlier-different speed-and then he said that they were working on a computer patch to address this issue. Why would they be working on it and have it due end of April if I am the only one with the issue? I am hopeful that it will resolve the issue-I know can tell you exactly when I hit 37-42 without looking at the speedometer and now realize how often I drive in that range.
  • runeriderrunerider Member Posts: 1
    You would be interested to know that when I picked up my Rx I almost turned around and gave it back because the "nibbling" was so profound. At times I don't feel it. Let me know if there's a fix.
  • wth18359wth18359 Member Posts: 2
    I'm glad (well, not really) to hear that someone else is experiencing a similar problem. I'm feeling what I would call a vibration at 42-45 MPH. I first thought it was tires, but after having them balanced, then installing winter tires, I'm convinced it is something else. It comes and goes. I almost always feel it when the engine is cold, and usually under light acceleration. There is no indication of anything odd on the display, such as quick switching from battery to ICE. The dealer has tried to find the problem twice, and they can't really feel it, let alone find it. I'm giving the dealer one more change to figure it out, then I'm calling Lexus.
  • lexus400lexus400 Member Posts: 8
    Are you still experiencing this issue. I have really been run around at my local dealer and Lexus customer care. At first this is a new problem, then I am the only person having this problem-then there is a fix in the works-interesting if I am the only one with the issue-or is a fix in the works. Since 500 miles I have been reporting the issue, I now have 10,000 miles and feel like I am being shaken to pieces between 37-42 mph. I am now onto the National Center of Dispute-and can't get the guy to even return my calls. For +$55,000 by the time that I added on all of the extras-I feel that I have a lemon or a car that wasn't ready for release. I have waitied now 4 months for the next month there will be a fix, now mid June according to the dealer, mid August according to Lexus. Anyone else with these issues-any fixes that have worked-any other proposed fixes????

  • gagricegagrice Pahrump, NevadaMember Posts: 31,450
    I am being shaken to pieces between 37-42 mph

    That sounds bad. Most of our surface streets are 35-40 MPH. Does your state have a Lemon Law. If you have all the dates you were at the dealer I would try to invoke the law. They may be trying to jack you around till the warranty expires. I would get a signed statement each time you take it in, stating they are working on the problem. Keep us posted.
  • lexus400lexus400 Member Posts: 8
    Thanks, I even told them that I was going to come into the service center every week. The manager asked why I would do that-I said that there was some law called a lemon law where I had to be in for something like 3 visits with them unable to fix the car. He flat out told me that I could tell them that and that they would just say that they couldn't duplicate the problem. I really fell like they are playing cat and mouse with me. My husband was ready to buy a new Lexus, and that has certainly been put on hold or maybe even out of the question. Thanks for the advice. I am trying to move on with the National Center for disputes but the guy that is supposed to return a call within 24 hours won't respond either. Guess next time I should buy a hunk of junk then I will expect a hunk of junk.

    Thanks for your response and I will keep you all posted.
  • doneby2010doneby2010 Member Posts: 27
    Have had 400h for 6 months (and 5000 miles) and don't have this problem. The car has a smooth ride and has no vibrations similar to what you described.

  • bobgailbobgail Member Posts: 12
    I am really concerned about all the reports of the engine "stuttering" at about 35-40 mph. Has anyone gotten a reasonable answer from a dealer? I have the 400H since last December. (05) I have driven it over 9000 miles and it has really been the "perfect". Of course, I am worried that the problem that has been reported may be inherent in the car. If so, I want to "head it off at the pass".

    Regarding the free service at 5k miles. I was unhappy with the dealer service for the following reasons;

    -they had me wait at least 2 hours before they reported that the service was completed.
    -they did not rotate the tires. (I marked them so I could tell)
    -they ignored the issues I brought to their attention. eg. squeeks.

    The dealer has all kinds of services they subscribe to in order to get a report about how "wonderful" they were with my car. When they called me, I let them have it! The next day, the customer service rep from the dealer called me up to find out why I was so unhappy with their service. She asked me what they could do to rectify the problems. I said; Pick up my car and leave me the loaner until you deliver it to me with the service completed and do it next time for no charge. They agreed and sent me a letter confirming the free service. We will see about the car pick up.

    Another thought-- The prices they charge for an oil change and tire rotation are outrageous. I think its about $70 in Florida. Not as bad as getting a Porche done for $300. I have always done my own oil changes on the Lexus rx300- vin tage 2000. I use only Mobile 1 and Toyota oil filters. The car has 189k miles and runs like the day I bought it. I would like to sell the car, but when people see the milage, they run as fast as they can.

    Good luck with the stuttering.

  • lexus400lexus400 Member Posts: 8
    Consider yourself one of the lucky ones. My dealer told me 2 weeks ago that he has 6 of them with this issue and that mine is the worst one that he has. Hope that they will address this issue and resolve it soon. I love the hybrid idea but need to be able to drive between 37-42 without nibbles/vibrations.
  • lxpatellxpatel Member Posts: 34
    I haven't had any problems with it either, 8k miles and 8 mos in service. Great gas mileage on highway, got 27 on trip from LA to San Diego and back, 80+ all the way.
  • jordanfjordanf Member Posts: 15
    Could someone tell me the difference between an interference and non-interference engine
  • lexus400lexus400 Member Posts: 8
    Well, the car still nibbles with 10,000 miles. They said the computer fix would be here July 4th week, it is the 17th and now they are saying it takes 30 days to get it from Japan-but I will be one of the first to get it.

    My father drove the car after taking up to the airport, and he said that he thought that he was going to get sick from the rocking/pulsing that was going on around 40 mph.

    I have called an arbitrator to start process and if they don't have a soulution very soon, I guess that is the next step. I should have given them the car back the first time because it was within the 30 day, but I believed them when they told me they were working on a fix. I thought that it would not be the right thing to do to give them the car back and demand my money back although at that point I had the legal right to do that. I thought that I was standing by my word to buy the car and that they would stand by their word to deliver a car worthy of the $55,000 price tag and Lexus name. Guess they are trying to prove me wrong and a fool!
  • PF_FlyerPF_Flyer Pennsylvania Furnace, PAMember Posts: 9,372
    In an interference engine, the valves open far enough into the cylinders that they "interfere" with the piston's space. The interference design actually improves the efficiency of the engine due to the wider opening valves, but if you run into a problem and the timing is off, the valves can actually strike the pistons, which is NOT a good thing at all.
  • dcaenendcaenen Member Posts: 1
    Had my Hybrid computer replaced with the new one yesterday, and the Nibbles are completely gone. If this bothers you too, I highly recommend you check it out. I guess there is no Service Bulletin.... my dealer didn't know about it, but the Toyota "Field Mechanical Specialist" did... Took 2 Days to get the new computer though... It was worth it.

  • swift725swift725 Member Posts: 2
    I love this truck but now when i start it in the morning even if its warm outside or cold, it runs real rough the first 5 minuets or so and hesitates. Replaced coil, plugs, rotor, throttle positioning valve, idle air sensor, and had injectors sent out and cleaned with new seals and screens. ALSO when truck is parked after runing to work or the store, i get back in it in about an hour and its hard starting. But if it sits all night it will start great just run rough for a bit. Or if I start it after its been hot or ran it before 45 minuets to an hour it will not be hard starting.... Please Help?? THX :confuse:
  • katzjamrkatzjamr Member Posts: 146
    as you can tell not all lexus dealers are created equal. the majority of us do not have this hesitation problem however i would be upset and not as patient as you if it was me. I do not understand why your dealer has not had the field office check your car, and replace the computer chip. Is there another more responsive dealer nearby you can go to? I would also document this in writing and make sure lexus corporate knows how you are being treated.
  • wth18359wth18359 Member Posts: 2
    dcaenen, where did you have the computer replaced? I have the same issue, and am going round and round with Lexus Customer Assistance after the dealer didn't have a fix. They are telling me they have not heard of the problem, and that it is "normal". From this and other forums, it's clear that there is a problem, and it can be resolved either by replacing the computer or performing the ECU update. At this point, I'm really disappointed in the response from Lexus. I came from an Acura MDX, which was a great vehicle. I wanted to try Lexus and the hybrid technology, but this may be my first and last Lexus if they can't admit to and resolve this issue.
  • apg97ssapg97ss Member Posts: 21
    since this topic board has been silent for awhile, maybe i am unlucky one. we have 2 week old RX400h and it hesitates, stutters, lacks power, etc at about 40mph and certainly at 60mph. this is happens at tame driving (i'm not pushing it). power meter oscillates up and down when all this going on. visiting service department tonight. if i get the 'this is normal' talk, i won't be happy. will let you know what happens.
  • katzjamrkatzjamr Member Posts: 146
    there is a known problem with a few of the 400h suv's that causes this stuttering at around 40 mpg, some can be reprogrammed however i would insist that factory reps, not the dealer go over your car as more extensive replacement of parts may be needed. i would drive another demo 400h if you want, i doubt it will have the same issue. btw i am assuming you dont drive with your left foot on the brake and right on the gas as the drive by wire system will have problems with this. sorry you are having this issue with a two week old vehicle. perhaps you can get a loaner 4ooh while yours in the shop to compare over a longer term.
  • apg97ssapg97ss Member Posts: 21
    Thanks for advice. will let you know how it goes. btw i am a one foot driver, and the foot is fairly light at that, so that is what is concerning. i'm not trying to win Indy, just cruise the highway at moderate speed, save gas, and have less tail pipe emissions. not fun to have the engine revs oscillating down the road in the process
  • apg97ssapg97ss Member Posts: 21
    Unfortunately, prediction came through. Dealer saying 'they can not duplicate problem.' Will escalate. Not happy.
  • eshapireshapir Member Posts: 24
    I can tell you that I felt a slight hesitation/oscillation when we first drove the car. We're up to 600 miles now and its totally gone away. I believe that during the first few hundred miles the car is analyzing the proper air/gas mix and I chalked it up to that.

    Hope your situation improves.

  • apg97ssapg97ss Member Posts: 21
    Thanks Ethan

    Yes, car now has 2,000 miles and has gotten better. Problem before was that at cruise at about 60 mph with constant gas peddle, power would oscillate up and down. Power still feels a little off, but oscillation is gone.
  • gtophgtoph Member Posts: 22
    Our 07 is still a baby with only around 350 miles on it, but I haven't notice any of the issues posted in here (knock on wood). I can tell when the ICE shuts on/off, but it's pretty minor and I wouldn't consider it out of the ordinary.
  • solar2000solar2000 Member Posts: 25
    Where do you get oil changes once your warranty runs out? I guess its possible that its too early since the rx400h just came out last year? But I'm guessing they probably have to be done at lexus? and how much are they usually? thanks!
  • hilandr05hilandr05 Member Posts: 18
    Since the RX400h has the same powertrain as the Toyota Highlander Hybrid, I take my 400 to a Toyota dealer that is closer than the Lexus dealer and MUCH less expensive. I got the oil and filter change yesterday for $27.12, including tax. I have over 16,000 miles on the 400 and this is my third oil change at the Toyota dealer.
  • hilandr05hilandr05 Member Posts: 18
    I have over 16,000 miles on my 400h and have never experienced this problem. If anyone else has it again, try turning on the cruise control on a level road and see if there is any difference under cruise control.
  • apg97ssapg97ss Member Posts: 21
    thanks. it appeared to get better on its own after some time. this was explained as the computer had to get calibrated. given my wife's driving, i dont know how any computer could calibrate to that (ha). seriously, it was a concern for first 1,000 miles and then seemed to get better after. will let this site know if re-occurs. thanks
  • texamau1texamau1 Member Posts: 42
    Does any one know if the Lexus 400h engine have timing belt or chain??
  • PF_FlyerPF_Flyer Pennsylvania Furnace, PAMember Posts: 9,372
    A quick search for replacement parts shows that it's a belt.
  • mokamotomokamoto Member Posts: 2
    Is anyone else experiencing a rattling noise coming from the ICE at idle? My 400h was among the first in the batch to come to the US as I was number 10 on the list in Hawaii. I've brought it to the dealer several time regarding the noise, and the tech noted that he hears the same rattling coming from the engine of other 400's. It's not a consistent rattle that has a rhythm or such, but a more irregular rattle that can be heard over the engines idle noise. The problem seems to be getting progressively worse as it would only occur on an occasional basis several months ago.

  • texamau1texamau1 Member Posts: 42
    pf_flyer, thanks for the info, it's look like the 3.3L is using the belt, how's about the new 3.5L ??
  • PF_FlyerPF_Flyer Pennsylvania Furnace, PAMember Posts: 9,372
    The 3.5 on the GS450h uses a chain.
  • gwoltmangwoltman Member Posts: 1
    I have the following problem: about 2 or 3 times in 10 the engine will not shut off as I coast through my hometown at very low speed. The engine has warmed up, I have my foot completely off the gas for 10+ seconds or am applying very light pressure at low speed (15 MPH) and the engine still runs. The battery is at 4,5, or 6 bars. It will not shut off until I come to a complete stop for 5 seconds.

    Does anyone else have this problem? Should I take it in under warranty? I still get 26-28 MPG so for the most part I'm satisfied, but this one thing irritates me.
  • wwestwwest Member Posts: 10,706
    The engine is also used to keep, maintain, the catalyst in the converter at ~800F.
  • apg97apg97 Member Posts: 2
    Well, it turns out the stuttering or pulsing or oscillating at 40 and then at 60 mph was real, and not my imagination after all. through helpful advice on 'Club Lexus' web site, i found that other people experienced same problem, and some were willing to fight lexus until this was recognized as legit. i must admit i didnt have the time or hard skull to fight as hard.

    So, now there is an 'official' technical service bulletin isssued by lexus. EG013-07 Title: "Rocking" Feeling at Highway Speed (Around 70 MPH)

    I went back to dealer today armed with this info, and after more convincing to take me seriously (more test drives with the tech who didnt sense anything wrong), they finally read this service bulletin after my insistence.

    It took a few hours to install the software patch. i just did a nice long, test drive tonight, and the problem is fixed. so nice to reach 60mph without feeling a powerless, shuttering blob. what a relief after putting up with this for 15,000 miles.

    so if there are others out there w this problem, you now have the cure at hand. you just have to bring Lexus a cure to fix their own vehicles, and you will be fine
  • texamau1texamau1 Member Posts: 42
    what's year/month is your RX400h?? because I do not have that stuttering/pulsing issue. I 've tried all range of speed (5mph-35mph in local road & 40pmph-80mph on hwy) :)
  • erlesnewserlesnews Member Posts: 1
    I recently completed a 4200 mile road trip in two weeks. After driving 800 miles the "water temp" msg came on and the red triangle was flashing. The main water temperature gauge read normal. I pulled into the Little Rock dealership and they spent 3 hrs checking it. Didn't need coolant. Things checked out. Went on my way and preceeded to have the problem again for another 12 times over the course of two weeks. The only common denominator was it only happened on days that were 88-95 degrees and only on the interstate. Once home my dealership tested and could find nothing. Anyone else have this problem????
  • roheyrohey Member Posts: 4
    Bought a certified 2007 for the wife a couple of months ago. I rarely drive it but had it out today on the freeway. It's impossible to keep at a steady speed. Even if I keep the gas completely steady the car sort of pulsates down the road as it ever so slightly speeds up and slows down. It's feels like the driver is constantly moving the gas pedal foot and you find yourself bobbing down the road. Is this just a charecteristic of the hybrid engine?
    I drive a C6 Corvette so the wife thinks I don't like the way it drives in general....but really it's quite irritating. Anyone else had this issue?
  • wwestwwest Member Posts: 10,706
    What about when using cruise control to sustain a steady speed...??

    Have you tried that..?? Same symptoms...??

    Almost all new cars use DBW, E-throttle, wherein the gas pedal is NOT connected mechanically to the throttle plate. The gas pedal is connected ONLY to the engine/transaxle controlling ECU.

    So the car can react to "pertubations" in the roadbed, along with MANY other circumstances, without any movement whatsoever of the gas pedal. For instance if the SOC of the hybrid battery is such that it requires use of the ICE for recharging the ICE RPM can rise to meet the additional HP/torque requirement but due to the CVT roadspeed should not be affected...."should not" being the operative term.
  • roheyrohey Member Posts: 4
    OK went and tested as wwest suggested with the cruise ON....interesting the pulsing goes away? This suggests it's not an engine problem but a computer issue. My original post was moved to this long established thread and it looks like this is a problem reported by others. So the car is headed to the shop Thursday for diagnois and most likely a computer software upgrade. Any other insight and experience with this issue would be appreciated.
  • wwestwwest Member Posts: 10,706
    You're probably going to find out this "pulsing" is the nature of the beast, SOP.
  • marmimarmi Member Posts: 3
    Yesterday, my Lexus RX400H, 2006, had a sudden surge in engine power as I was pulling into a parking space. It felt as though the car accelerated forward at an increasing speed after I was coasting into the space. It didn't stop until I rann into a wall...

    Has anyone else had this problem?? I know for certain that I was not pressing on the accelerator when this occured.
  • wwestwwest Member Posts: 10,706
    Check to be sure the floor mat has not slipped up behind the brake pedal but on top of a portion of the gas pedal.
  • upstatedocupstatedoc Member Posts: 710
    Did anyone catch the story on CNN about the doctors rx400h exploding in his driveway critically injuring him and also injuring 2 others? Just happened today. ATF and FBI do not suspect foul play. I'm sure lexus has a "team" on the way as well. Scary... :(
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