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2021 Polestar 2 - Weird Regen Braking & Grinding Noise

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Ashley M. · rep 0 · May 22, 7:45 AM · 1 replies · solved · Question

Vehicle: 2021 Polestar 2 Long Range Dual Motor

Hey everyone,

I've been noticing some peculiar behavior with my 2021 Polestar 2 Long Range Dual Motor lately and wanted to see if anyone else has experienced something similar. The regenerative braking feels really inconsistent. Sometimes it's super strong, almost throwing me forward, and other times it barely seems to engage, especially at lower speeds when coming to a stop.

On top of that, I've started hearing a grinding noise, particularly when I'm applying the brakes lightly to come to a full stop. It's not constant, but it's definitely noticeable and sounds like it's coming from the front wheels. I know EVs use friction brakes less, so I'm a bit confused.

Is this normal for Polestars or EVs in general? Should I be concerned about the grinding noise? Any ideas what might be causing these issues with my 2021 Polestar 2?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 7:45 AM

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Hi Sarah, it sounds like you're experiencing a couple of common concerns with EV braking systems, particularly the blend of regenerative and friction braking.

Here are some potential causes and steps you can take:

Potential Causes for Inconsistent Regenerative Braking:

  1. Battery State of Charge (SoC) and Temperature: Regenerative braking efficiency is often reduced when your battery is nearly full (typically above 80-90% SoC) or when the battery is very cold or extremely hot. The car's system limits energy input to protect the battery. This is a normal protective function.
  2. Brake System Calibration/Software: Software glitches or sensor issues can sometimes affect how the car smoothly blends regenerative braking with the physical friction brakes. Ensure your Polestar 2 has the latest software updates, as these often include braking system improvements and calibrations.
  3. Driving Conditions: Steep descents or specific driving modes (e.g., 'One Pedal Drive' settings) can influence how regen feels.

Potential Causes for Grinding Noise:

  1. Brake Pad/Rotor Condition: Even with strong regen, friction brakes are still used, especially for the final stop. Grinding can indicate normal surface rust buildup on rotors (common after rain, washing, or sitting overnight), worn brake pads, or even small debris caught between the pad and rotor.
  2. Brake Caliper Issues: A sticking or partially seized brake caliper can cause constant, light contact between the pad and rotor, leading to noise and premature wear.
  3. Regenerative Braking System Actuator: While less common, issues with the electronic actuators that manage the blend of regen and friction braking could potentially manifest as unusual noises.

What You Can Do:

  1. Observe Conditions: Pay attention to when the regen inconsistency occurs (e.g., battery SoC, outside temperature).
  2. Visual Inspection: If safe, briefly inspect your brake rotors for excessive rust or scoring, and check pad thickness if visible.
  3. Test Braking: Find a safe, open area and perform a few firm, controlled stops to help clean off any surface rust or minor debris from the rotors.
  4. Check for Updates: Verify your Polestar 2's software is up to date.

When to See a Shop:

  • If the grinding noise is persistent, loud, or accompanied by a noticeable change in pedal feel (e.g., sponginess, vibration).
  • If the braking performance feels significantly reduced or unsafe.
  • If any warning lights related to the braking system (e.g., ABS, ESC, brake system warning) appear on your dashboard.
  • A Polestar service center has specialized diagnostic tools to check for fault codes, assess the health of your brake components, and evaluate the performance of the regenerative braking system. They can accurately diagnose whether it's a normal characteristic, a wear item, or a system malfunction.
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