In short, absolutely not.
But the question raises the issue of “What is co-redemption?” The title “Co-Redemptrix” indicates the Catholic belief that Our Lord Jesus Christ enabled Mary to co-operate with him as a secondary agent, dependent entirely on him as primary agent, in procuring the Price of Human Salvation. The claim raises many deep concerns among Protestants. The theological objection that many Protestants use is, “Whatever you attribute to Mary, you take away from Christ.” The objection sounds reasonable. But in fact, it is erroneous. We do not detract from Christ by extolling the legitimate glory of Mary — Rather, we magnify it! A brief argument shows how this is the case.
Here’s a key principle: A cause which can bring about a greater effect is greater than one that can’t.
Another point: A thing is greater if it can cause an effect than it would be if it could not.
Conclusion: A cause which can bring about an effect that itself can cause an effect is greater than a cause that can only bring about inert effects (effects that don’t cause).
Application to Christ and Mary: If Christ is able to bring it about that Mary herself can co-operate with him in procuring the world’s salvation, he is a greater cause than if he is not able to do this. With this simple observation, we see that the Protestant objection is null and void. In fact, we turn the objection on its head: Precisely because Christ can enable another to co-operate with him, he is all the more glorious a redeemer!
Of course, this raises the next logical question: Wait! Your response would work if it is possible for Christ to do this. Maybe it is not possible! Maybe it is a contradiction in terms!!! And what is not possible cannot factor into your basic premise (“A cause which can bring about a greater effect is greater than one that can’t.) What’s the contradiction in terms? Someone will readily object: Mary is herself redeemed by Jesus Christ. But if she is redeemed by Christ, she cannot co-operate in the redemption of the world. Just like all other human beings, she is the fruit of redemption and not its active cause. A thoughtful objection, to which the next post shall respond.