Chad pressed the ignition sequence on the diagnostic tablet. The Pagani's V12 turned over with a deep guttural roar, then immediately stuttered. The dashboard lit up like a Christmas tree. Six fault codes cascaded down the diagnostic screen in rapid succession. The hybrid system warning flashed.
The e-motor relay clicked on, clicked off, clicked on again. The engine shuddered and dropped to a rough, uneven idle. Todd took a step back. "Same thing every single time."
Fletcher didn't move. His eyes were closed, his hands still on the block. He was counting.
"Click. Pause. Click. Click. Pause. Click."
The relay was cycling in an irregular pattern. Not random, sequential. It was following a command set. But the commands were wrong.
Fletcher opened his eyes. "Pull up the ECU firmware version," he said. Chad tapped the diagnostic screen. A string of numbers appeared. HY-BC.4.2.7-MOD.
Fletcher shook his head. "That's your problem. Right there." "What do you mean?" Chad leaned in.
"The Huayra BC shipped with firmware version 4.1.3. Pagani released an update, 4.2.7, in late 2019. But 4.2.7 was designed for the Huayra Roadster BC, not the coupe. The coupe uses a different e-motor relay mapping, different voltage thresholds, different timing protocols."
Chad stared at the screen. His face went pale. "Someone installed the Roadster firmware on a coupe."
Fletcher continued. "Probably during a routine service update. The ECU thinks it's talking to a Roadster relay. The relay thinks it's listening to a coupe controller. They're speaking two different languages, and the system keeps throwing fault codes because neither side can agree on what normal looks like."
Chad pulled up the service history on his tablet. His fingers were shaking. He scrolled through months of entries, oil changes, brake inspections, tire rotations, until he found it. March 14th. Routine firmware update performed by Whitmore Motors service department.
Firmware version HY-BC.4.2.7-MOD. "Oh my God," Chad whispered. Todd looked over his shoulder. "We did this?"
"We did this." Chad's voice was hollow. "Eight months ago we installed the wrong firmware and nobody caught it."
Through the glass, Victoria's expression hadn't changed, but her knuckles were white around her crossed arms. Fletcher was already moving to the second problem. He pulled a penlight from his jacket pocket, a small LED flashlight scratched and dented, the same one his grandfather used to carry. He leaned deep into the engine bay tracing the wiring harness from the hybrid relay to the temperature sensor cluster.
"Somebody hand me a mirror."