Team Penske has completed its investigation into why Will Power’s car refused to start while leading the opening race of IndyCar’s Detroit doubleheader under a red flag.

In a post-race interview, the frustrated 2018 Indy 500 winner expressed strong convictions for what he believed to be the cause of the problems as the No. 12 Chevy sat motionless on pitlane as the rest of the field — including eventual winner Marcus Ericsson — pulled away to resume the race.

Citing extreme temperatures below the bodywork of the No. 12 Chevy on a hot and humid day, Power was concerned about the effects from a delay in his mechanics receiving permission to apply external cooling fans to the car’s electronics once the field came to a stop on pit lane. According to Power, the main culprit for losing a likely win was an overheated engine control unit (ECU).

While Power’s initial heat-related worries had merit, Team Penske spent Monday conducting bench tests of the No. 12’s electronics and confirmed heat was not a factor. For those who recall the troubled start to the 2020 season at Texas Motor Speedway when Ryan Hunter-Reay’s car refused to fire on the grid, Power experienced the same issue as the ECU went into “boot mode.”

According to Penske managing director Ron Ruzewski, a familiar problem with the spec McLaren Applied Technologies TAG-400i ECU reared its head and left the race leader sitting idle as every other car refired and completed the race.

“What we have discovered is, through the chain of events that happened, when Will was coming to a stop and shutting the car off, it appears that the shut-down sequence was different than expected,” Ruzewski told RACER. “There has been a known issue for a couple of years, and it can happen on start-up or shut-down. If the sequence is out of order, the ECU can get confused and go into a ‘boot mode’ just like your PC does when it doesn’t like something.

“And if there’s a change in state it doesn’t agree with, it can get stuck, and just like your PC where you’ve got to hold the power button down for five seconds to get it to restart, it was a very similar thing here.”

The reason for the ECU problem stemmed from the car’s “Intelligent Power System” made by Cosworth. According to a number of data acquisition specialists on pit lane, the IPS – which manages all of the car’s power – can trip the ECU into boot mode if anything other than the correct start or shut-down sequence is performed. The three-phase toggle switch has Position 0 (P0), which is off, P1 which turns on most of the car’s electronics, and P2, which is ignition.

Restrictions over the number of crew members that can touch a car during red flag periods meant that Penske had no way to accurately diagnose Power’s problem on the spot. Barry Cantrell/Motorsport Images

“A couple years ago, Cosworth had recommended some logic be put into the IPSs by the teams to program in some delays to try and driver-proof the system,” Ruzewski said. “It seems that there were still some flaws in some of the logic as we had in that car.”

The IPS expects a specific time delay between the switch being moved from one position to the next – two-second pauses from P0 to P1 to P2, or P2 to P1 to P0, for example – and if someone moves the switch too fast and changes the state in, say, 1.5 seconds, the IPS is known to confuse the ECU and cause it to fall into boot mode.

Although Power’s crew members were shown trying to start the car, with one mechanic attempting to run through the start-up switch sequence, Ruzewski says there was no chance the No. 12 would have fired.

“As Will was coasting to a stop, somehow, the ECU got into a boot mode when the car shut down, and honestly, it had nothing to do with the crew guys starting the car; what had been done was already done,” Ruzewski said.

“We’d never seen this situation before this, this kind of chain of events, and the only way we would have regained the IPS would have been for the engine guy to plug into the car.”

With only two people permitted to interact with each car as they sit on pit lane during a red flag, one would have needed to leave the car for a Chevy engine technician to visit with a laptop and communicate with the IPS and ECU. As IndyCar was giving the two No. 12 crew members multiple opportunities to start the car – all while nobody on the team knew what was causing the problem – there wasn’t enough time for a Chevy tech to diagnose and resolve the issue as the field behind Power pulled away from pit lane.

“The only way to get it out of that mode would be for the engine guy to plug in the cable to basically reflash the ECU,” Ruzewski confirmed. “So, in the case of our issue, we did initially think that it could have been a heat issue, but that wasn’t it. Once we got the car back to the pit box, we actually changed the ECU. It was hot to the touch, but not like it was scorching your fingers.

“So before that, we plugged in the electronics comms (ED: communications) cable to the car, and the engine guy confirmed he had no comms with the ECU; it wasn’t communicating. We double-checked one more time, we had no comms and it didn’t instantly come back. At that point in time, rather than try and force comms to the ECU, we got the new ECU in the car, had comms when we powered back up, started the car, and we went out. The long and short of it is that it was unfortunate event that put the put the ECU into a boot mode and we’ll try and learn from it so it doesn’t happen to us again.”

It’s also worth noting that while IndyCar received criticism for not allowing crew members to go straight to their cars once they arrived on pit lane under the red flag, it followed its procedures without change from the first red flag for Felix Rosenqvist’s crash, and other recent red flags.

The standard procedure is to wait for all cars to stop before IndyCar’s pit technicians give the OK for crews to attend to their cars. That permission is often granted within 30 seconds of the last car coming to a halt. In the case of how the series handled the controversial second red flag, extra time and heat, as Team Penske has confirmed, played no part in the No. 12’s failure to fire.