IsItAGoodCar
Reliability Guide

Common Problems with the
2021 Mazda CX-30 (DM)

By 2021 the CX-30 had established itself as one of the most refined and driver-focused compact crossovers. Software updates had resolved many early issues.

What changed for 2021

  • •Software updates resolving early issues
  • •SkyActiv-X reliability proven
  • •Improved infotainment stability
  • •Strong used values reflecting quality

Common MOT watch-outs

  • !12V battery weakness on short-trip cars
  • !Paint thinness showing chips
  • !Keyless entry system checks
4
Known Issues
1
Serious
1
Moderate
2
Minor

All Known Issues

Smart Brake Support (SBS) False Positives

SeriousElectrics & Electronics

Early models were prone to "phantom braking" where the car detects a non-existent obstacle and applies the brakes.

Est. Repair Cost: £0 (Software update)
Warning Signs:

Unexpected emergency braking, SBS warning message on dashboard

What to Inspect:
  • Verify recall work has been completed
  • Check for latest software updates
Verified by IsItAGoodCar Research Team

12V Battery Drain

ModerateElectrics & Electronics

The 12V battery can discharge unexpectedly, often due to the keyless entry system or other modules not entering "sleep" mode correctly.

Est. Repair Cost: £100–£200
Warning Signs:

Car won't start after being left for a few days, Low battery warnings

What to Inspect:
  • Ask if the battery has been replaced or if software updates for the BCM have been applied
Verified by IsItAGoodCar Research Team

Low-Speed Brake Squeal

MinorBrakes

Some CX-30s exhibit a high-pitched squeal when braking at very low speeds, often addressed by Mazda with specialised shims.

Est. Repair Cost: £0–£100
Warning Signs:

Squealing noise when braking at low speed, Noise disappears at higher speeds

What to Inspect:
  • Test brakes in a car park at low speed
Verified by IsItAGoodCar Research Team

Power Tailgate Malfunction

MinorElectrics & Electronics

The electric tailgate can fail to open, fail to close, or beep incessantly due to sensor or software issues.

Est. Repair Cost: £200–£600
Warning Signs:

Tailgate reverses when closing, Beeping sounds but no movement

What to Inspect:
  • Test the tailgate multiple times using both the button and the key fob
Verified by IsItAGoodCar Research Team

Buying Tips for 2021 Mazda CX-30 (DM)

  • Battery drain is a common complaint; consider a trickle charger if the car is rarely used.
  • Check for software updates regarding the Smart Brake Support system.
  • Ensure the infotainment system has the latest firmware to avoid glitches.
20202022
Check a 2021 Mazda CX-30 (DM) by Registration