Can a defendant who has pleaded guilty to a charge under section 1237 of the Criminal Code, challenge the sentence on appeal?

plea . . . [A] defendant cannot admit the sufficiency of the evidence by pleading guilty and then question the evidence by an appeal under section 1237.5 [citation]"]; see People v. Young (2000) 77 Cal.App.4th 827, 829 ["'a challenge to a negotiated sentence imposed as part of a plea bargain is properly viewed as a challenge to the validity of the plea itself' and therefore requires that the defendant 'seek and obtain a probable cause certificate in order to attack the sentence on appeal'"].)