TRAVERSE CITY, MI – Chrysler engineers have figured out what caused the problem with the Dodge Dart press car that got a WardsAuto editor only a third of the way here for the Center for Automotive Research’s Management Briefing Seminars.

Along the highway at about 70 mph (113 km/h) on Sunday afternoon, the car shuddered and both the “check engine” and electronic throttle control lights came on simultaneously. The owner’s manual said the car should not be driven. A fellow WardsAuto staffer picked up the editor on the way north.

After evaluating the car on Monday, Chrysler says the pre-production Dart had been used recently for diagnostic purposes to replicate a fault code with the accelerator-pedal position sensor.

In the process of running the test, engineers had used an overlay harness that bent some of the pedal sensor’s connector pins. As a result, some of the pins weren’t lined up properly, which allowed the connector to loosen up, triggering a fault and the lights on the instrument panel.

“We are very sorry that this was missed,” the auto maker says. The car is being repaired.

Chrysler delivered a replacement vehicle to Traverse City on Monday.

Until the problem arose, the Dart was averaging about 25.9 mpg (9.0 L/100 km) in a mix of city and highway driving.