Will not start because of a flat 12 V battery on the Yaris and Yaris Cross hybrids

Engine / equipment

1.5 hybrid: fourth-generation Toyota Yaris and Yaris Cross

Period mentioned

2020–2024

Symptoms

After a few days parked, the car will not start (it does not go to “Ready”) because the auxiliary 12 V battery is very low or flat. It mainly affects people who drive few kilometres.

Possible cause described

According to an internal 2024 Toyota technical note reported by L'argus (March 2025), the original 12 V battery was too small to recharge quickly enough while driving. Since February 2024, Yaris and Yaris Cross built in France and the Czech Republic have an LN0 12 V 35 Ah battery with twice the charge capacity.

Check for the garage

Measure and test the 12 V battery. If the car was built before February 2024, ask Toyota to replace it with the new higher-capacity battery (the part number depends on whether the battery was fitted before or after October 2024). In the meantime, make somewhat longer trips or use a battery maintainer if the car stays parked for days.

Cost cited in the source

Toyota replaces it under the 3-year or 100,000 km warranty.A rough figure from the original database, not an up-to-date quote.

Sources from the original database