After the Q1 accident Verstappen complained of a 150bhp power surge, prompting cynical responses from some of his F1 rivals.
Although some observers suggested there may have been a technical problem - possibly a sticking throttle - Horner insisted there were no mechanical issues, and the accident was actually triggered by Verstappen's foot jumping on the throttle pedal as he ran over the kerbs.
"It wasn't a stuck throttle," Horner told Autosport. "I think when he got high on the kerb there was an oscillation on the foot. It was fairly obvious.
"The gearshift around there has always been a bit lumpy, and I think it was a combination of that, pushing flat out, up on the kerb, oscillation with the foot.
"Put a lot of stuff together, that's what happens. There's nothing to read into it."
Renault Sport boss Cyril Abiteboul confirmed the French manufacturer had found nothing wrong in its investigations.
"The engine has done exactly what the throttle was asking, it was very clear," he told Autosport.
"It's a determinist thing - cause and consequence, when you press on the throttle, something is happening to the engine.
"The engine has reacted in exactly the same way that it was supposed to react."
Renault driver Nico Hulkenberg was one of the immediate sceptics, suggesting after qualifying in Bahrain it was not possible for the engine to surge like that on its own.
"I would like to know where the 150 horsepowers are coming from," he said. "Does he have a party mode as well?
"I haven't experienced that. It doesn't change from one lap to another. Let me put it like this - that's Greek to me."