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2018 S550 Transmission Jerking/Hard Shifting at Low Speeds

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Mike T. · rep 0 · May 25, 3:04 AM · 1 replies · solved · Question

Vehicle: 2018 Mercedes-Benz S550 W222

Hi everyone,

I'm experiencing a concerning issue with my 2018 Mercedes-Benz S550 (W222). The transmission has started to feel very jerky, especially when shifting at lower speeds, typically between 1st and 3rd gear. It's not a constant problem, but it's happening more frequently now, making for a very uncomfortable ride.

There's no Check Engine Light or any specific transmission warning lights on the dash, which makes it harder to diagnose. I've heard about potential software updates for Mercedes transmissions, or even issues with the valve body. The car has around 60,000 miles.

Has anyone with a W222 S-Class encountered similar hard shifting or jerking? What was the cause and solution? I'm hoping it's not a major transmission overhaul.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:04 AM

0

ClearTheCode admin answer:

Hard shifting or jerking in your 2018 Mercedes-Benz S550's transmission, especially at low speeds and without a Check Engine Light, can be a nuanced issue. The S-Class uses sophisticated automatic transmissions, and these symptoms often point to either control system issues or mechanical wear.

Here's a look at potential causes and what steps to consider:

  1. Common Causes for Hard Shifting/Jerking (No CEL):

    • Transmission Software/Adaptations: Mercedes-Benz transmissions learn your driving style. Sometimes, adaptations can get skewed, or a software update is needed to resolve known shifting anomalies.
    • Low or Contaminated Transmission Fluid: While Mercedes often touts 'lifetime' fluid, regular changes are crucial for longevity, especially at 60,000 miles. Low fluid levels or degraded fluid can cause pressure issues.
    • Valve Body Issues: The valve body is the 'brain' of the automatic transmission, directing fluid pressure to engage gears. Solenoids within the valve body can stick or fail, leading to harsh shifts. This is a known potential issue across various Mercedes models.
    • Speed Sensors within Transmission: Internal transmission speed sensors can sometimes give erratic readings, confusing the transmission control unit (TCU).
    • Engine Mounts/Transmission Mounts: Worn mounts can amplify the feeling of harsh shifts, making them seem worse than they are.
    • Torque Converter: Less common, but a failing torque converter can cause shuddering or harsh engagement.

  2. Diagnostic Steps:

    • Check for Stored Codes: Even without a Check Engine Light, a professional-grade scanner can often pull 'pending' or 'history' codes from the Transmission Control Unit (TCU) that aren't severe enough to light up the dash.
    • Review Service History: Confirm when the transmission fluid and filter were last changed. If it hasn't been done, this is a good starting point.
    • Observe Patterns: Note exactly when the jerking occurs (specific gears, temperature, acceleration level) to help a technician narrow down the problem.

  3. When to See a Shop:

    • Given the complexity of Mercedes-Benz transmissions and the potential cost of repairs, it's highly recommended to take your S550 to a reputable Mercedes-Benz specialist or dealership as soon as possible.
    • They have the specialized diagnostic equipment (like XENTRY/DAS) to read specific TCU codes, check fluid levels accurately (which often requires special tools), and perform software updates or re-adaptations.
    • Attempting DIY transmission work without the proper knowledge and tools can lead to further damage. Early diagnosis can prevent a minor issue from becoming a major, expensive transmission overhaul.
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