The Arrow McLaren driver took over the lead following the clash between polesitter Romain Grosjean and Scott McLaughlin, and was working hard to hold off the charging Ericsson in the closing stages of the event.
But exiting the final corner at the end of lap 96, O'Ward's Chevrolet engine suffered a flash plenum fire which forces a driver to briefly back off the throttle.
The hiccup was just long enough to allow Chip Ganassi Racing driver Ericsson into the lead, and O’Ward barely held off the Swede’s team-mate Scott Dixon in the final four laps to secure second.
“We did everything right today, I've got to give it to the team,” said O’Ward.
“Not just our #5 car, but Felix [Rosenqvist], Alex [Rossi], their groups, as well – I feel like we've all really collaborated fantastically and come with a package that has been a massive step up to where we were last year, so that's super promising. Super happy with that…
“Sadly, it’s just very annoying to give it away like that. Nothing else I could have done.
“It shut off with a plenum fire. You have to let off, get back to it.
“It comes up randomly. You can't really predict it. So yeah, we just have to have a look into it.
“We ended up with some great points. We started the year like we wanted to, right?
“But they're very valuable points at the end of the day. We just got 10 points thrown away.
“We'll have a look at all the data and stuff and then just make sure how for that not to happen and look forward to Dallas.”
Despite Ericsson’s comments to the contrary, O’Ward is confident he could have held on to the lead through to the checkered flag had he not suffered the plenum event.
“I think we would have been just fine,” he stated.
“We were managing a one-second gap, and I don't think Marcus was going to get us.
“Right at the exit [of the final turn], we kind of lost drive and gained it back. We were lucky not to get passed by Scott.
“I don't know what else to tell you. It's very unfortunate.”
His new Arrow McLaren team-mate Rossi came home in fourth, while Rosenqvist was sidelined by damage from a coming together with Dixon on the opening lap for which the Kiwi later apologised.
Rosenqvist lost 40 laps while repairs were effected and was classified 19th.
“He said he didn’t see me and he actually came up to apologise afterwards, which was nice of him,” said Rosenqvist.
“We’re always fine. It was just one of those things.”
