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2021 CX-30 Transmission Shifting Hard - Limp Mode? P0700 Code

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Mike T. · rep 0 · May 25, 3:31 AM · 1 replies · solved · Question

Vehicle: 2021 Mazda CX-30 Select

Hey Mazda community,

I'm having some worrying issues with my 2021 Mazda CX-30 Select, which has just under 40,000 miles. Lately, the transmission has been shifting very harshly, especially between 2nd and 3rd gear. Today, it felt like it went into some kind of 'limp mode' – the car felt sluggish, and the RPMs were higher than usual for the speed. The check engine light came on, and my basic scanner pulled a P0700 code.

I know P0700 is a generic transmission control system malfunction, but it doesn't tell me much specifically. Has anyone experienced this with their CX-30? What are the common causes for this kind of transmission behavior and code on these models?

I'm concerned about driving it too much. Any advice on what I should look into or expect before taking it to a dealership?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:31 AM

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ClearTheCode admin answer:

A P0700 code indicates that the Transmission Control Module (TCM) has detected a fault in the transmission system and has illuminated the Check Engine Light. This code is a general informational code, meaning there are other, more specific transmission-related codes stored in the TCM that your basic scanner might not be able to access. The harsh shifting and limp mode are classic symptoms of a transmission fault.

  1. Check Transmission Fluid: Start by checking the transmission fluid level and condition. Low fluid can cause shifting issues. Also, note the color and smell of the fluid; burnt smell or dark color can indicate internal transmission wear. Refer to your owner's manual for the correct checking procedure.
  2. Scan for Specific Codes: A P0700 code almost always comes with one or more specific 'P07xx' codes stored in the TCM. A more advanced OBD-II scanner capable of reading transmission-specific codes is necessary to pinpoint the exact issue (e.g., P0705 for transmission range sensor, P0740 for torque converter clutch circuit, etc.).
  3. Electrical Connections: Inspect the electrical connectors to the transmission and the TCM for any signs of corrosion, damage, or looseness. A poor connection can disrupt communication or sensor readings.
  4. Battery Condition: While less common, a weak car battery or charging system issue can sometimes cause erratic electronic behavior, including transmission control problems. Ensure your battery is healthy.

When to see a shop: Given that your vehicle is in limp mode and exhibiting harsh shifting, it's highly recommended to have your Mazda CX-30 professionally diagnosed as soon as possible. Driving with these symptoms can potentially cause further damage to the transmission. A qualified technician will have the necessary diagnostic tools to read the specific P07xx codes from the TCM, perform transmission fluid pressure tests, and inspect internal components or solenoids to accurately diagnose and repair the issue.

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