2018 Lexus RX 350 · Engine & transmission control
Bucking on early upshifts or low-speed surge
Lexus's ECM bulletin calls for reprogramming only after a technician reproduces one of two narrow driving patterns.
What the reviewed source says
Start with the documented condition, not a parts guess.
Lexus documented two related drivability conditions on some 2016 to 2019 RX 350 and RX 350L vehicles: brief back-and-forth bucking just after the first two upshifts, and a rocking surge below 46 mph while the transmission is in a higher gear with the torque converter fully locked. The bulletin specifies ECM reprogramming after a technician reproduces the exact condition and rules out other faults.
Words owners may use
Does this match the moment?
Symptoms in the pattern
- A brief bucking sensation immediately after a 1 to 2 or 2 to 3 upshift
- A repeated rocking or surge not directly tied to a shift
- The surge occurs between 0 and 46 mph with the torque converter in full lock-up
- The sensation dissipates rather than continuing as a constant vibration
Vehicles and scope
- 2016 to 2019 Lexus RX 350
- Specified 2018 to 2019 RX 350L calibrations are included
- Drivetrain, WMI and current calibration determine applicability
Manufacturer position
What the official procedure directs
Lexus directs technicians to reproduce the exact bucking or surge criteria, check for applicable calibration IDs and reprogram the ECM. The bulletin specifically says not to replace the ECM as part of this repair.
The bulletin does not set a mileage threshold. It stated Federal Emissions Warranty coverage of 96 months or 80,000 miles for the specified condition, subject to the vehicle's in-service date and eligibility.
Original evidence
Open the documents behind this page.
Repair paths and safe checks
Separate the diagnosis from the action.
Confirm the drive pattern and update the ECM calibration
A Lexus technician uses vehicle data to reproduce the published condition, checks the current calibration and installs the applicable updated ECM software.
Do not replace transmission parts solely from the symptom wording. The bulletin applies only when its operating criteria and calibration checks match.
What owners reported
Did this repair fix the same symptom on your car?
Loading owner reports…
Record when the motion occurs
From the passenger seat or after the trip, note the road speed and whether the event follows a shift. Add the engine temperature and any warning light.
Do not attempt repeated acceleration tests in traffic or operate a phone while driving.
What owners reported
Did this repair fix the same symptom on your car?
Loading owner reports…
Useful before authorizing work
Read the method beside the problem
These guides explain the safety and evidence checks that apply to this problem file.
Bulletin, recall or warranty?
Three official looking documents can describe the same bad part while creating very different rights. The document number, VIN scope and remedy language matter more than what someone called it at the service counter.
Read guide ↗Car shudders or vibrates
A useful diagnosis starts with when the vibration happens and where you feel it. The word shudder alone does not identify a transmission fault.
Read guide ↗More for this model
Other reviewed Lexus RX 350 conditions
2017 Lexus RX 350 · Brakes & vehicle control
Brake booster vacuum pump may lose braking assist
NHTSA campaign 18V211000 lists the 2017 Lexus RX 350 for a condition in which brake booster vacuum pump may lose braking assist.
2015 Lexus RX 350 · Fuel, battery & fire risk
Fuel delivery pipe may leak in the engine compartment
NHTSA campaign 14V576000 lists the 2015 Lexus RX 350 for a condition in which fuel delivery pipe may leak in the engine compartment.
2023 Lexus RX 350 · Steering & vehicle control
Spiral cable connection may deactivate the driver airbag
NHTSA campaign 23V480000 lists the 2023 Lexus RX 350 for a condition in which spiral cable connection may deactivate the driver airbag.