Miles on your RX400h?
Rookie
Joined: Oct 2020
Posts: 28
Likes: 7
From: PP
Mine, 2006, has 188K on it and recently got the hybrid battery replace (used hybrid battery). It costs me $750 including labor.
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left side is my old battery, right side is the new one ripped down from a 2008 model.
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left side is my old battery, right side is the new one ripped down from a 2008 model.
Rookie
Joined: Jul 2021
Posts: 47
Likes: 5
From: AZ
I changed all 6 spark plugs and 3 ignition coils. All denso parts from Toyota instead of Lexus.
Car has become very responsive and acceleration has improved.
Another difference is it engages the hybrid system much better when I drive local and slows down the vehicle instead of cruising.
In highways the hybrid is engaging during downhills and also regenerates in cruise mode.
My mileage has jumped from 23.6 conservative driving to 26.1 mpg at 75 mph.
Car has become very responsive and acceleration has improved.
Another difference is it engages the hybrid system much better when I drive local and slows down the vehicle instead of cruising.
In highways the hybrid is engaging during downhills and also regenerates in cruise mode.
My mileage has jumped from 23.6 conservative driving to 26.1 mpg at 75 mph.
7th Gear
Joined: Oct 2014
Posts: 7
Likes: 7
From: South Carolina
As of today, 249K on all original components. Two timing belts, a set of plugs and replaced all ignition coils as preventive maintenance. Replaced the two front oxygen sensors as well for PM. Only had to do pads and rotors at 150K. Just be mindful of the vents below the rear passenger seats and keep them clear for ventilation so the battery will not overheat.. I cleaned out the filter on battery every 100K.
Getting about 25.9 MPG on regular gas.
Getting about 25.9 MPG on regular gas.
Driver
Joined: Jul 2001
Posts: 73
Likes: 5
From: Always on LSD
1st Gear
Joined: Mar 2026
Posts: 1
Likes: 1
I just bought a 2006 model year off of marketplace, it currently has 285k miles on it I’m hoping it will get me by with its supposedly great fuel economy, I don’t think the battery has ever been changed in mine. the closest Lexus dealer is about 300 miles away… 
10th Gear
Joined: Feb 2026
Posts: 10
Likes: 4
2006 rx400, now has 129k on it,absolutley zero service history,
took a chance as it was reasonably cheap,
bought at 109k did cambelt and w/pump,
then replaced rear shocks as they were shot and leaking,
first drive was a 600 mile round trip no problems and returned 37mpg
over the next year it gave good service then,
had a few minor snags, stuck caliper, leaky rad,, then the big one hit
vsc flashing on the highway and completley died, coasted in to the shoulder, code was loss of communication to battery system,Hmm
went through every thing and seemed to be cured until it happened again, and again ,long story short the A.C compressor was trying to take 500v and overloading the hybrid system, but by turning the complete heating system off it was ok,so a used compressor was fitted recharged a,c and all good for a few months,
then again vsc and complete stop,loss of comms to battery system again,, so stripped out the entire hybrid system batteries and master control unit, cleaned everything of corrosion and damp,all good,for a couple thou, then on the highway it did it again, BUT a slightly different code,
turned out,one of the cooling fans for the hybrid batteries, was sending the wrong signal down the B.line (now known as the K line)to the ecu this was causing the system to think the batteries were to hot so blasted all 3 fans at highest setting and tripped the system,bought a used fan, swapped one and used the launch diag to drive the fans through speed 1 to 6 in increments,hit the jackpot with the first swap! put original fan back in and it tripped at speed 3, ok what can be done to prevent it in future? pretty simple really,the faulty fan was sending a horrific wave form to the ecu which looked suspiciously like an rf signal,so fitted RF blockers on all three feed lines to the ecu,so the signal is smoothed and 6k later never had a single problem
A by product of all this work was the hybrid batteries now chage up to about 80 percent then are used till back down to 20 percent, then it starts charging them again and repeats all the time, only ever goes into the green if on a long high speed run then the car uses them to give really good fuel consumption,I now get 39mpg on straight long runs, and 35.7 on local runs of about 14 miles, and I am back in love with the car!
took a chance as it was reasonably cheap,
bought at 109k did cambelt and w/pump,
then replaced rear shocks as they were shot and leaking,
first drive was a 600 mile round trip no problems and returned 37mpg
over the next year it gave good service then,
had a few minor snags, stuck caliper, leaky rad,, then the big one hit
vsc flashing on the highway and completley died, coasted in to the shoulder, code was loss of communication to battery system,Hmm
went through every thing and seemed to be cured until it happened again, and again ,long story short the A.C compressor was trying to take 500v and overloading the hybrid system, but by turning the complete heating system off it was ok,so a used compressor was fitted recharged a,c and all good for a few months,
then again vsc and complete stop,loss of comms to battery system again,, so stripped out the entire hybrid system batteries and master control unit, cleaned everything of corrosion and damp,all good,for a couple thou, then on the highway it did it again, BUT a slightly different code,
turned out,one of the cooling fans for the hybrid batteries, was sending the wrong signal down the B.line (now known as the K line)to the ecu this was causing the system to think the batteries were to hot so blasted all 3 fans at highest setting and tripped the system,bought a used fan, swapped one and used the launch diag to drive the fans through speed 1 to 6 in increments,hit the jackpot with the first swap! put original fan back in and it tripped at speed 3, ok what can be done to prevent it in future? pretty simple really,the faulty fan was sending a horrific wave form to the ecu which looked suspiciously like an rf signal,so fitted RF blockers on all three feed lines to the ecu,so the signal is smoothed and 6k later never had a single problem
A by product of all this work was the hybrid batteries now chage up to about 80 percent then are used till back down to 20 percent, then it starts charging them again and repeats all the time, only ever goes into the green if on a long high speed run then the car uses them to give really good fuel consumption,I now get 39mpg on straight long runs, and 35.7 on local runs of about 14 miles, and I am back in love with the car!