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2017 Regal GS - Transmission Shifting Hard, No Codes Yet

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David L. · rep 0 · May 25, 2:43 AM · 1 replies · solved · Question

Vehicle: 2017 Buick Regal GS

Hello Buick owners,

I'm having a concerning issue with my 2017 Buick Regal GS, 2.0L turbo, with around 70,000 miles. Recently, the automatic transmission has started shifting very harshly, especially from 1st to 2nd gear, and sometimes downshifting feels clunky too. It's not constant, but it's happening more frequently.

I've checked for codes with my basic OBD-II scanner, but there's no Check Engine Light and no pending codes. I'm worried about the transmission, but without a code, I'm not sure where to start. Could it be low fluid, a solenoid issue, or something more serious?

Has anyone with a Regal experienced similar hard shifting without an immediate code? What was the culprit? Any advice on what to look for or if this is a known issue for this model year?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:43 AM

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ClearTheCode admin answer: Hard shifting on your 2017 Buick Regal GS, even without a diagnostic trouble code (DTC), is a symptom that warrants immediate attention to prevent further damage to the transmission. Modern transmissions are complex, and issues can arise before a CEL is triggered.

Possible Causes:

  • Low or Contaminated Transmission Fluid: Incorrect fluid level or degraded fluid can cause pressure issues and poor shifting.
  • Transmission Solenoids: Shifting solenoids can stick or fail, leading to erratic or harsh shifts.
  • Valve Body Issues: The valve body directs fluid pressure to engage clutches and bands; issues here can cause shifting problems.
  • Internal Transmission Wear: Worn clutch packs or other internal components can lead to hard shifts.
  • Software Glitch/Adaptation: Sometimes, the transmission control module (TCM) can have a software issue or require a re-learn procedure.
  • Engine Mounts: Worn engine or transmission mounts can sometimes exacerbate the feeling of harsh shifts.

Troubleshooting Steps:

  1. Check Transmission Fluid Level and Condition: Consult your owner's manual for the correct procedure to check fluid level (often done with the engine running and warm). Note the fluid's color and smell. Burnt smell or dark color indicates contamination.
  2. Professional Scan Tool Diagnosis: A basic OBD-II scanner may not read transmission-specific codes. A professional-grade scan tool can access the Transmission Control Module (TCM) for proprietary codes, live data (like solenoid operation and fluid temperature), and potential software updates.
  3. Inspect Engine/Transmission Mounts: Visually inspect the mounts for cracks or excessive wear. Worn mounts can make shifts feel more jarring.
  4. Note Specific Conditions: Pay close attention to when the hard shifts occur (cold, hot, specific gears, acceleration, deceleration). This information is crucial for diagnosis.

When to See a Shop:

  • Immediately, if the hard shifting is severe, or if you notice any grinding noises or complete loss of a gear.
  • If you are unable to check the transmission fluid correctly or assess its condition.
  • If a professional scan tool is needed to pull specific TCM codes and live data.
  • Transmission issues are best handled by a qualified mechanic or a transmission specialist, as they require specific expertise and tools for diagnosis and repair.
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