Chevrolet Bolt 2027 battery drain problem and BECM software update
GM expanded a Service Update for some Chevrolet Bolt 2027 EVs after software could drain both the high-voltage and 12-volt batteries. The fix is a BECM reflash and a full charge.
Only 345 vehicles were included in the initial list — GM later expanded the campaign. On some Chevrolet Bolt 2027 vehicles, software serving the RESS traction battery can unintentionally cause both the high-voltage pack and the low-voltage 12-volt battery to discharge. The first version of service bulletin N262559000 was issued on June 11, while the July revision N262559000-01 expanded the affected VIN list and added reprogramming of the Battery Energy Control Module. GM has not disclosed the final number of vehicles after the expansion.
The fix does not require replacing cells, the battery pack or other parts. The dealer first updates the BECM software, then must charge the traction battery to 100% and wait for the Charge Complete message. A full charge is required to reset the cell-balancing software. Level 1, Level 2 and DC fast charging are all permitted for the procedure.
The full charge is especially notable because, even outside this service campaign, Chevrolet recommends regularly charging the Bolt 2027 to 100% so the vehicle can accurately display available range and the state of charge of its LFP battery. This unusual charging rule had already been discussed in an earlier look at the Chevrolet Bolt 2027. For vehicles in the service list, however, a 100% charge is now a mandatory part of the factory repair procedure.
It is important not to call this a recall. GM classifies the document as a Service Update, not a safety recall. The manufacturer even says it does not want owners to make a special service visit: the work should be carried out when an affected vehicle is already at the dealer for scheduled maintenance or another reason. The campaign runs through July 31, 2028, and the repair may be performed only by an authorized EV dealer with a properly trained technician.
The Bolt 2027 itself uses a 65 kWh LFP battery, offers up to 422 km of EPA-rated range and supports DC fast charging at up to 150 kW. The model has recently been praised for its combination of price and practicality, including in testing and comparisons with rivals. That makes this campaign notable not for its still-unknown scale, but for the nature of the defect: it is software-related and can affect two separate power sources in the vehicle at the same time.
For owners, the key criterion is the VIN. The bulletin explicitly requires the dealer to verify the status of the specific vehicle before starting work; simply owning a Bolt 2027 does not mean the vehicle is included in the campaign.