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Jerky Shifts in My 2016 IS 350 F Sport - Transmission Issue?

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Mike T. · rep 0 · May 25, 3:30 AM · 1 replies · solved · Question

Vehicle: 2016 Lexus IS 350 F Sport

My 2016 Lexus IS 350 F Sport has developed a noticeable jerky or harsh shift, especially when downshifting at lower speeds, like coming to a stop. It's not constant, but it's happening more frequently now. It feels like a small jolt through the car, which is very unlike Lexus smoothness.

The car has about 70,000 miles on it, and I'm concerned it might be a transmission problem. Is this a known issue for the 8-speed automatic in these IS models? I'm wondering if a transmission fluid flush or software update might help, or if it's something more serious. No check engine light has come on yet.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:30 AM

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ClearTheCode admin answer:

Rough or jerky shifts in your 2016 Lexus IS 350 F Sport, especially at 70,000 miles, warrant attention. While the 8-speed automatic transmission in these models is generally robust, several factors can lead to the symptoms you're describing:

  1. Transmission Fluid Condition: Over time, transmission fluid can degrade, lose its lubricating properties, and accumulate wear particles. This can lead to increased friction and harsh shifts. While Lexus often states 'lifetime' fluid, it's generally recommended for inspection or replacement around this mileage, especially under severe driving conditions.
  2. Transmission Software Updates (TSBs): Lexus, like other manufacturers, sometimes releases software updates for the Transmission Control Module (TCM) to refine shift logic, address known quirks, or improve overall drivability. There might be a Technical Service Bulletin (TSB) specifically addressing harsh downshifts for your model year. A dealership can check for and apply these updates.
  3. Solenoid Issues: The transmission uses solenoids to control fluid flow and engage different gears. A failing or sticking solenoid can cause erratic shifting. This often manifests as specific gear-related issues.
  4. Valve Body Problems: The valve body is the hydraulic control center of the transmission. Wear or blockages within it can affect fluid pressure and lead to shifting problems.
  5. Engine Mounts: Less common, but worn engine or transmission mounts can sometimes exaggerate the feeling of a harsh shift, making it feel more pronounced.

OBD Codes:

  • If the issue progresses and the transmission control module detects a fault, you might see a Check Engine Light (CEL) and codes such as P0700 (Transmission Control System Malfunction), or more specific codes related to gear ratio errors or solenoid performance.

When to See a Shop:

  • Immediately: If the shifting becomes consistently harsh, you hear grinding noises, or the car struggles to engage gears.
  • Soon: If the problem persists despite checking basic items. A Lexus dealership or a reputable transmission specialist can perform a diagnostic scan to check for pending codes, inspect transmission fluid, and determine if a software update or a more involved repair (like solenoid replacement or valve body service) is needed. Do not wait for a CEL if the issue is impacting driving experience.
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