Haas' 2025 car has a deep-rooted flaw, team principal Ayao Komatsu has conceded.
In late 2023, team owner Gene Haas, fed up with the small American squad's dismal results, ousted Gunther Steiner and tapped senior engineer Komatsu to take charge.
The team leapt forward last year, only to plummet again in 2025 so far.
"It was a big surprise," Komatsu told reporters in Shanghai.
"In Bahrain for testing the car wasn't perfect, but we didn't expect anything anywhere near as bad as we saw in Melbourne," the Japanese said.
"Honestly, in the first practice when the car came out, I thought either something is broken or something is completely wrong. When we determined that nothing was broken, we thought 'Ok, we have a big problem'."
The upside, Komatsu said, is that engineers "clearly understand" the issue. "It's a combination of aerodynamic oscillation and our rear downforce characteristics," he explained.
"If you only had one, you could live with it. But when you combine them, the car becomes very difficult to drive."
The downside? "We have to figure out what part of the car we need to change to solve this performance problem," he said.
"Some of it may be relatively short-term solutions, but some of it will be an iterative process both in CFD and wind tunnel. You will not see a solution in the upcoming races. So yes, it is quite serious."
One theory points to Ferrari's simulator, also used by Haas. Post-Melbourne reports hinted Ferrari's own 2025 woes stemmed from incorrect sim data.
"We put more performance on the car over the winter," Komatsu maintained. "You drive in the simulator, you do simulations, and it's all fine.
"But when we got to turn 10 in Melbourne, it all came crashing down. At least we found out early. Imagine if we had been mediocre for five, six, seven races before we found out we have a serious fundamental problem.
"Everyone was shocked. For some, it took a day to accept that we have a serious problem. Now everyone is working diligently to solve it.
"No one is asking questions about whether we have a problem or not. We do," he admitted.
Komatsu ruled out abandoning 2025 for the 2026 rules overhaul. "If you just leave it and move on, who can guarantee that similar things won't happen in the future," he said.
