Ford Motor Co. has lost summary judgment against many of the claims alleging defects in sparkplugs in more than 2 million vehicles.

U.S. District Judge Benita Pearson ruled that claims that Ford committed consumer fraud by omitting material facts about its sparkplugs can proceed in six bellwether proceedings. The plaintiffs argue that Ford’s multipiece spark plug produce carbon deposits that lock the plugs in place and that they often get stuck.

The litigation involves bellwether plaintiffs from Florida, Illinois, Michigan, Ohio, New Jersey and Texas making claims about 35 vehicles. According to the opinion, customers had to pay $1,700 on average to extrace sparkplugs from cylinder heads and to repair or replace their engines.

Pearson also ruled that the plaintiffs’ claims that Ford is equitably estopped from enforcing its express warranty limitations can survive summary judgment. She reasoned that the plaintiffs can proceed under the theory that they paid excessive money for sparkplug maintenance and repair.

The judge ruled that Ohio plaintiffs can proceed with claims that Ford was negligent and violated an implied warranty in tort.

But the judge, presiding over federal multidistrict litigation regarding Ford sparkplugs and engine products, ruled that some plaintiffs lack standing to challenge Ford’s express warranty as unconscionable because they purchased their vehicles used. She granted summary judgment to Ford on any statutory fraud claims based on affirmative misrepresentation by the carmaker.

Pearson ruled that none of the plaintiffs can advance a theory that their vehicles lost value due to the cost of replacing “one component out of thousands at 100,000 miles.” The Ohio federal judge also ruled that some plaintiffs from Texas, Ohio and Florida failed to provide notice of the alleged breach of their express warranties as required in their home states. She ruled that one Ohio plaintiff failed to show that his Mustang GT was negligently designed.

“Ford contends that plaintiffs have not cited a single case in which a product that performs as intended for its useful life (in this case 100,000 miles), but costs more to replace than plaintiffs think it should at the end of its useful life, actually gives rise to a claim that is not merchantable; that it breached some express warranty which expired many tens of thousands of miles ago; or that the failure ignites a duty to disclose the potential replacement costs of that product on a vehicle that has thousands of components,” Pearson said.

She agreed with some but not all of Ford’s argument.

In a separate ruling last week, Pearson approved the expert witnesses for both sides in the litigation.

Amaris Elliott-Engel contributes to