Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Lexus RX 400h Engine Problems



  • hilandr05hilandr05 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 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 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 Posts: 42
    Does any one know if the Lexus 400h engine have timing belt or chain??
  • PF_FlyerPF_Flyer Pennsylvania Furnace, PAPosts: 6,368
    A quick search for replacement parts shows that it's a belt.


    Need some roadside assistance? - or send a private message by clicking on my name.

    Share your vehicle reviews

  • mokamotomokamoto 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 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, PAPosts: 6,368
    The 3.5 on the GS450h uses a chain.


    Need some roadside assistance? - or send a private message by clicking on my name.

    Share your vehicle reviews

  • gwoltmangwoltman 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 Posts: 10,706
    The engine is also used to keep, maintain, the catalyst in the converter at ~800F.
  • apg97apg97 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 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 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 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 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 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 Posts: 10,706
    You're probably going to find out this "pulsing" is the nature of the beast, SOP.
  • marmimarmi 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 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.
  • 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... :(
  • roheyrohey Posts: 4
    pulsing is gone......They the flash program listed in the TSB and all is fine. Never acknowledged it was a known problem and di not want to have anything to do with the copy of the TSB I brought it????? Oh well the wife's rig is a pleasure to drive again.
  • Looks like it was a bomb...I don't know whats scarier.
  • nmrknmrk Posts: 8
    I have a 2006 Lexus 400 hydrid. It surges when I am braking. I do not have a floor mat causing the problem. The problem is intermittent. I have not been able to establish a "pattern of behavior." It always surprises me. I never take my foot off the brake when coming to a stop or slowing down because I don't trust the car NOT to surge. Yes--I have raised the question with Lexus. I am always the ONLY person to have the problem.

    At least I now know there are two of us.
  • wwestwwest Posts: 10,706
    What you may be experiencing is "pre-activation" of ABS. Sometimes the anti-lock system detects just a very slight bit of inordinant wheel rotational rate deceleration and the initial action of the anti-lock system will be to INSTANTLY disable regen braking. The "event" is short enough, or the loss of regen braking is effective enough, that full ABS activation does not occur. The brake pressure release solenoid(s) are never activated (no brake pedal ABS "feedback") and so you end up puzzled about just what happened.

    A slight bump in the roadbed, steel plate, even a "plastic" roadway marking, can cause this effect.
  • nmrknmrk Posts: 8

    Thank you for your response. Sounds a little technical but I think I understand. In any event, it sounds like I need not be worried about the "little surge". I had read about major surges and was concerned that my problem might be exacerbated. NMRK
  • marmimarmi Posts: 3
    to wwest:
    I was thankful to get your message about your surging problem when braking. I also have not been aable to establish a "pattern of behavior" and am paranoid when I come to a stop. My surge led me into a brick wall and was a very costly incident-today I received a new insurance bill that tripled my insurance rate. The dealership checked it out and said it could not have happened the way I described it. I checked my floor mat and of course it was not the problem. I don't know if it will take a terribly unfortunate accident for Lexus to solve this problem, but I am thinking of getting rid of my car, which I love otherwise. I am sure there are not just "the two of us" who have experienced this event.
  • I have had this problem with my Lexus RX400H 2006 MANY times. I think this is probably a widespread problem that often goes unreported. I have actually gotten used to this happening. It is intermittant as another respondant had written. This makes it unpredictable so I'm always prepared to brake harder with my foot covering the brake pedal. It seems to happen most often when I'm not trying to come to a complete stop such as slowly rolling through the Easy-pass lane on the thruway toll booths, etc. I have never reported this issue to my Lexus dealer and I haven't had the best trust in them. I'm sure they would blow smoke. I'm having several other problems with this vehicle including trouble starting it with the headlights on AUTO. Also the navigation system won't accept ANY local addresses all of a sudden (says "address does not exist." Poor dealership relatons plus these BUGS in the vehicle made me a dissatisfied LEXUS owner.
  • marmimarmi Posts: 3
    Thank you for replying to my post- your problem happened precisely as did mine-mine when rolling to a stop in a parking lane and yours, for instance when rolling through the toll booth lane. I would urge you to report this intermittent problem to your Lexus dealer, if only to establish a paper trail. When I had my surge, I hit a brick building. What if a person or another vehicle were in front of us? I ended up having a point on my driving record which cost me insurancewise-it could, however be much more serious-is your vehicle a hybrid, by the way?
  • wwestwwest Posts: 10,706
    I have probably said this before, but...

    These are FWD vehicles, so it is EXTREMELY important not to allow braking of ANY kind, engine, regen, or actual frictional braking, to result in wheelskid/slip and therefore raise the potential for an accident due to loss of directional control.

    To that end VW has just introduced a new engine RPM control design that will automatically up-rev the engine should the driver inadvertently downshift to a level wherein the rotation decline of the front driven wheels is so rapid lockup will soon result.

    So we may now see a resurgence of FWD amd F/awd vehicles with stick shifting.

    "..rolling through a toll booth...."


    Metal expansion joint, slightly WET metal expansion joint.....??

    Or "plastic" road striping, WET "plastic" road striping...??

    Most modern Anti-lock systems are desired to pre-empt wheelskid/lockup by sensing that the wheel(s) rotation rate is decling so rapidly the lockup will soon result. With light to moderate braking and with the hybrid battery SOC being fairly low you may very well be relying on regen braking ENTIRELY.

    If ABS activation is required then regen must first be INSTANTLY cancelled in favor of frictional braking ONLY. For a programmer there is no simple nor easy solution to this problem. The best solution, given the situation, need for ABS due to impending wheel lockup, it seems to me that it would be better/best to bring the frictional braking on line in a moderate way. Previous regen braking level was heading toward wheelskid/lockup, best to bring frictional braking on line at a slightly lower braking level.

    So the driver feels a "lurch" forward.....

    As I have said before, why not disable ABS altogether unless VSC indicates maintenance of directional control, directional correction, is required..?

    The most of those brief instances of low traction due to expansion joints, plastic striping, and "bumps", would be transparent, "non-events".
  • nmrknmrk Posts: 8
    I have read your explanations re the surge--but am now confused. What should I do to either deal with or get rid of this surge problem. I haven't run into anything but it worries me. I am also thinking of getting rid of the car. I like it but don't trust it. On the other hand--is this a common problem with cars utilizing similar technology?

    Thanks for your attempt to educate me--but now I am confused.

Sign In or Register to comment.
Lexus RX 400h Engine Problems - Page 2 - Car Forums at