General Motors says it has replaced faulty ignition switches on just under 20 percent of 2.6 million small cars that are being recalled.
The company has repaired just over 491,000 cars that are covered by the recall announced in February.
Switch maker Delphi Automotive says it has produced over 1 million parts and expects to have made 2 million by the end of August. GM says it expects all parts to be made by late October.
Delphi CEO Rodney O'Neal tells lawmakers his company has added three lines to speed up production.
Some car owners have complained it's taking too long for GM to finish repairs.
The switches can slip into the accessory position and unexpectedly shut off engines. That has caused crashes that killed at least 13 people.
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