EV charging

EV charger lights flashing red

Warning Do not attempt any electrical or gas work yourself. Always use a qualified, MCS-certified, or Gas Safe registered professional for repairs.

What you’re seeing (symptoms)

The main status LED on your charger has turned red or is flashing in a specific sequence (e.g. 3 flashes, then a pause). Charging has stopped, and the app may show a “Hardware Fault” or “Safety Lockout.”

What’s normal vs not normal

Normal:

  • A solid green or blue light while charging.
  • A white or pulsing blue light when the car is plugged in but waiting for a cheap off-peak schedule.

Not normal:

  • Any red light (flashing or solid).
  • The unit being completely dark (no lights) while the car is plugged in.
  • The red light appearing only when it rains.

Likely causes (ranked)

  1. Earth fault (PEN fault): The charger has detected a dangerous voltage on the earth wire. Most modern UK chargers have built-in “PEN fault” protection to prevent electric shocks.
  2. Over-voltage / Under-voltage: The electricity supply from the grid is currently unstable (too high or too low for safety).
  3. Over-temperature: The unit has become too hot during a high-power charging session and has shut down to cool.
  4. DC leakage: A safety sensor has detected electricity “leaking” where it shouldn’t.
  5. Relay failure: An internal mechanical switch has become stuck.

Quick checks you can do safely

  • Unplug the car: Sometimes the fault is with the vehicle’s own charging system. Unplug the cable and see if the light turns back to green/blue.
  • Check the manual: Count the number of red flashes. Your manual will have a “Fault Code” table (e.g. 2 flashes = Over-temperature).
  • Feel the unit: If the charger is in direct sunlight and feels very hot, wait for it to cool down in the shade.
  • Hard reset: Switch the charger off at the main breaker for 5 minutes, then switch it back on.

When to call an installer

  • Immediately if the red light returns instantly after a hard reset.
  • If you see any brown/black scorch marks on the unit or the plug.
  • If the red light only appears when it’s raining (suggests water ingress).

Questions to ask your installer

  • “Does the unit require an additional earth rod, or is the built-in PEN protection sufficient?”
  • “Can you check the tightness of the electrical connections inside the unit?”
  • “Is the unit’s firmware up to date to ensure the safety sensors are correctly calibrated?”

Related NetZeroNow tools & guides

FAQs

What is a PEN fault? In the UK, many houses share an “earth” and “neutral” wire from the grid. If this wire breaks, it can make the metal shell of your car “live.” UK chargers must detect this and disconnect the car immediately. Can I reset a red light? Yes, usually by cycling the power at the fuse box. However, if the fault is a real safety issue (like an earth fault), the unit will (and should) turn red again immediately. Does it mean my car is broken? Rarely. It’s almost always an issue with the electrical supply to the charger or the charger’s own internal safety sensors. Why does it happen at night? Over-voltage faults often happen at night when the grid is under low load and the voltage from the local substation can rise slightly above the legal limit. Is red always bad? Yes. In the world of EV chargers, a red light is a universal symbol for “I have stopped for safety reasons.”\n

Written by NetZeroNow | Last updated on 2026-03-02