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2018 G80 Rough Shifts & Hesitation - Is there a TSB?

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Laura J. · rep 0 · May 22, 6:24 AM · 1 replies · solved · Question

Vehicle: 2018 Genesis G80 3.8L

Hey everyone, I've been noticing some pretty rough shifts in my 2018 Genesis G80 3.8L, especially at lower speeds and when downshifting. Sometimes it feels like the transmission hesitates before engaging a gear, almost like a slight lurch.

It's not constant, but it's becoming more frequent and quite noticeable. It's particularly apparent when accelerating from a stop or slowing down in traffic.

I'm wondering if anyone else with a similar model year G80 has experienced this? Is this a known issue, or perhaps something covered by a Technical Service Bulletin (TSB)?

I'm trying to gather some info before taking it to the dealer, as I'd like to be as informed as possible. Any insights or similar experiences would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 6:24 AM

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ClearTheCode admin answer:

  1. Identify the Problem: Rough shifting and hesitation in automatic transmissions, particularly at lower speeds or during downshifts, are common concerns that can stem from various sources. For your 2018 Genesis G80 3.8L, this could indicate a need for a software update or a more mechanical inspection.

  2. Potential Causes:

    • Transmission Control Module (TCM) Software: Often, manufacturers release software updates to refine shift logic, improve smoothness, and address minor glitches. This is a very common fix for such symptoms and is often covered by a TSB.
    • Low or Contaminated Transmission Fluid: Incorrect fluid levels or degraded fluid quality can lead to poor lubrication and hydraulic pressure issues, affecting shift performance.
    • Valve Body Issues: The valve body directs transmission fluid to engage gears. Wear or blockages in the valve body can cause erratic shifting.
    • Sensor Malfunctions: Sensors like the transmission input/output speed sensors or throttle position sensor can send incorrect data to the TCM, leading to improper shift points.

  3. Common OBD-II Codes: While rough shifting might not always trigger a Check Engine Light immediately, if the issue progresses, you might see codes related to transmission performance, such as:

    • P0700: Transmission Control System Malfunction (a generic code indicating the TCM has a fault and wants the MIL illuminated).
    • P0731 - P0736: Incorrect Gear Ratio (specific to which gear is slipping or not engaging correctly).

  4. When to See a Shop:

    • Immediately: If you experience severe lurching, grinding noises, or the transmission slips out of gear, pull over safely and have the vehicle towed to a shop.
    • Soon: If the rough shifting is consistent, worsening, or if a Check Engine Light illuminates. It's best to address these issues promptly to prevent more extensive and costly repairs.
    • Recommended Action: Start by checking for any active Technical Service Bulletins (TSBs) for your specific 2018 Genesis G80 related to transmission performance. Many dealers can check this for you. A diagnostic scan at a Genesis dealership or a reputable independent shop is crucial. They can check for software updates, inspect transmission fluid condition, and perform a thorough diagnostic to pinpoint the exact cause.
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