Issues about whether you are guilty or innocent are “waived” by a guilty or no contest plea – this means that you cannot raise these arguments at all.
Such issues usually concern whether the evidence the prosecution collected was reliable, admissible at trial, or enough to prove you were guilty of the charges.
For example, after taking a plea bargain, you cannot argue that the evidence was insufficient to support the charges, that a police lineup was unfair, that police illegally coerced you to confess, that witnesses were not credible, or that the court was wrong in ruling that certain evidence would be admissible at trial.
Other issues that cannot be raised following a guilty plea are claims about procedural matters that might have affected the fairness of the trial. These include denial of a defense motion to sever the trial of multiple charges or multiple defendants or denial of a motion for a continuance.
If your plea includes agreement to a specified sentence or a specified maximum term, you waive your right to challenge that sentence the ground that it violates Penal Code prohibition on double punishment for the same act or course or conduct.