SAN FRANCISCO (CBS SF) – Some Pacific Gas and Electric Co. SmartMeters can overcharge customers when they become too hot.

Officials said on Monday that almost 1,600 of the wireless electricity and gas meters across Northern and Central California were found to be affected by the defect.

READ MORE: Downsized But Not Out, Dreamforce Conference Set to Boost Business in San Francisco

KCBS’ Dave Padilla Reports:

They sometimes misread electricity usage when their internal temperature goes over 100 degrees.

READ MORE: Emmy Awards: 'The Crown' Dominates with Seven Wins

PG&E officials say they have replaced or will replace the defective meters. Affected customers will also receive refunds averaging $40 as well as a $25 credit.

The digital SmartMeters are used by many utilities across the country. PG&E has installed nearly 8 million and has plans for another 2 million.

MORE NEWS: Flames Reach Ancient Sequoias; Crews in Pitched Battle to Save Giant Forest Grove

(Copyright 2011 by CBS San Francisco. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. Wire services may have contributed to this report.)