A US$0.9bn pre-tax charge related to GM Korea restructuring has reduced General Motors' first quarter 2018 operating income by 58.7% year on year to $1.1bn.
Sales revenue was down 3.1% to $36.1bn.
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EBIT-adjusted was off 26.6% to $2.6bn.
The EBIT-adjusted margin slipped 2.3 points to 7.2%.
The automaker said this was due to "full-size truck launch-related downtime" though the launch was "on plan".
EBIT-adjusted for North America was $2.2bn compared with $3.5bn a year ago.
The margin of 8.0% was on track to sustain 10% for the full year.
"Results this quarter were in line with our expectations with planned, lower production in North America related to the transition to our [redesigned] Chevrolet Silverado and GMC Sierra," said chairman and CEO Mary Barra.
"We are on plan to deliver another strong year in 2018."
The $0.9bn charge was related to the recent announcement GM would end production and close the Gunsan plant by the end of May 2018.
The $942m pre-tax charge related to asset impairment and termination benefits and included $464m in non-cash asset impairments.
International operations' EBIT-adjusted was flat at $0.2bn.
GM highlighted record equity income in China of $0.6bn and "continued improvement" in South America.
It delivered 715,794 vehicles in the US, up 4% ahead of an estimated industry increase of about 2%.
"We were profitable in all operating segments, including record performance in China and for GM Financial (EBT-adjusted of $0.4bn versus $0.2bn. Our Q1 results were on plan and we remain confident in the full year guidance we announced in January," said CFO Chuck Stevens.
GM China's first quarter sales reached a record 986,052 units.
