NEV Owner Guide

EV Over-the-Air (OTA) Updates Explained: What the Rules Require

Published 2026-10-06 · Updated 2026-10-06

EV Over-the-Air Updates Explained

Many new electric cars update their software over the air, the same way a phone does. A notification pops up, you agree, and some time later the car has new features, fixes or changed behaviour. Manufacturers advertise it. Zeekr's European leaflet for the 7X, for example, lists "Over-The-Air software updates" under connectivity (Zeekr 7X leaflet).

For owners, the practical questions are: what can an update change, can it go wrong, and what protections exist? The main rulebook is UN Regulation No. 156, which covers software updates for vehicle type approval in countries that apply it. This guide explains what it requires, in plain English.

Checked on 6 October 2026. This is a general explainer, not legal advice. Which rules apply depends on your country and your car's approval.

What is UN Regulation 156?

UN R156 sets "uniform provisions concerning the approval of vehicles with regards to software update and software updates management system". The version published in the EU's Official Journal gives its date of entry into force as 22 January 2021 (R156, OJ L 82).

It works on two levels:

  1. The manufacturer must have a certified Software Update Management System: documented processes for managing, recording and securing updates.
  2. The vehicle type must meet specific requirements, including extra ones for updates delivered over the air.

Rules for the manufacturer

The regulation requires manufacturers to have processes that, among other things (R156, para 7.1):

  • uniquely identify every initial and updated software version, including data used to validate its integrity (7.1.1.2)
  • for cars that have a RXSWIN (an identifier for type-approval-relevant software), keep track of it before and after each update (7.1.1.3)
  • confirm an update is compatible with the target cars' last known configuration before issuing it (7.1.1.7)
  • assess and record whether an update adds, changes or enables functions that weren't there when the car was approved (7.1.1.9)
  • let the vehicle user be informed about updates (7.1.1.11)

It also requires manufacturers to protect the RXSWIN and software versions on a vehicle against unauthorised modification (R156, para 7.2.1.2.3).

Rules for over-the-air updates

Paragraph 7.2.2 sets out what the car itself must do when it receives an OTA update (R156):

Requirement What it means for you
Recovery (7.2.2.1.1) If an update fails or is interrupted, the car must be able to go back to the previous version or be placed in a safe state
Enough power (7.2.2.1.2) An update can only run when the car has enough power to finish it, including enough to recover if it fails
Safe execution (7.2.2.1.3) If an update could affect safety, the manufacturer must show it will run only when the car is in a state where that's safe
Information before (7.2.2.2) You must be able to see the purpose of the update, what it changes, how long it will take, what won't work during it, and any instructions
Can't drive if unsafe (7.2.2.3) Where updating while driving may not be safe, the car must not be drivable during the update, and you must not be able to use functions that would affect safety or the update
Information after (7.2.2.4) You must be told whether the update succeeded or failed, and what changed, including any user manual updates
Preconditions (7.2.2.5) The car must check that preconditions are met before installing

The "information before" list is worth knowing. Under 7.2.2.2 the purpose can include whether the update is for a recall, safety or security. If an update notice doesn't tell you what it's for or how long it takes, that's something to ask your dealer about.

What OTA updates can change

The regulation defines how updates must be managed, not what they contain. Its own wording shows the range: an update can be for recall, safety or security purposes (7.2.2.2), and manufacturers must assess whether it will add, alter or enable functions that weren't present when the car was approved (7.1.1.9). So an update can be a small fix or a change to how the car behaves.

The MG4 brochure, for instance, describes an app that lets owners check battery status and schedule charging (MG4 brochure). Charging schedules like this are set through software, so after any update it's worth checking they still work the way you set them.

Your home charger updates too

In Great Britain, home chargers sold under the smart charge point regulations must also take secure software updates. Schedule 1 requires a charger's software to be securely updated using adequate cryptographic measures, and sets other security rules, such as banning shared default passwords (Smart Charge Points Regulations, Schedule 1). Our UK home charger guide covers the rest of those rules.

A practical checklist for owners

  • Read the update notice. Look for purpose, duration and what won't work during installation.
  • Install when you don't need the car. If the update says the car can't be driven, schedule it overnight.
  • Keep enough charge. The car checks power before updating, but starting with a healthy state of charge avoids delays.
  • Park somewhere with good signal if your car downloads over mobile data.
  • Check the result screen. Confirm the update succeeded and read what changed.
  • Re-check your charging settings. Schedules and charge limits are worth a quick look after any update. For how full to charge day to day, see LFP vs NMC: should you charge to 100%?
  • Ask the dealer about recall updates. If an update is for a recall, the notice should say so.

Does an update affect running costs?

If you think an update has changed your car's efficiency, don't guess. Compare your real consumption before and after. Track it for a few weeks, then put the figure into the EV charging cost calculator to see what it means per 100 km and per month.

Sources

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