De Villota lost her right eye and suffered facial and head injuries in the incident at Duxford, when she crashed at slow speed in to the back of a truck as she conducted straight-line aerodynamic work.
Alongside an investigation being conducted by the Health and Safety Executive and another commissioned by an independent forensic body, Marussia also conducted its own in-depth look at what happened.
And although the specifics of what caused the accident have not been confirmed yet, Marussia issued a statement on Monday revealing that the crash was not caused by a failure on the car.
Team principal John Booth said: "We are satisfied that the findings of our internal investigation exclude the car as a factor in the accident. We have shared and discussed our findings with the HSE for their consideration as part of their ongoing investigation.
"This has been a necessarily thorough process in order to understand the cause of the accident. We have now concluded our investigatory work and can again focus on the priority, which continues to be Maria's wellbeing. In that regard, we continue to support Maria and the De Villota family in any way we can."
De Villota is now out of sedation in hospital and able to talk to her family as she continues her recovery.