With regard to a 2nd or 3rd DUI anywhere in California and not just San Diego you have the potential to have the first DUI (or second) DUI removed from your record.
This can be done by challenging the constitutionality of your prior DUI convictions pursuant to Vehicle Code sections 23624 and 41403.
You can “move to strike the prior” by filing a motion with the court specifying the deprivation of constitutional rights according to Vehicle Code §41403(a). This motion must not only be served (given) to the court on your first (or second) DUI but also to the prosecutor in your current case at least five court days before the hearing.
At the hearing, the prosecution has the initial burden of producing evidence of the separate conviction sufficient to justify a finding that the defendant has a separate conviction. The defendant then has the burden of proving by a preponderance of the evidence that his or her constitutional rights were infringed in your first case and if you meets this burden, the prosecution has a right to produce rebuttal evidence. At the end of this hearing the court must make a finding based on the evidence, and must strike the separate conviction from the accusatory pleading if the court finds that the separate conviction is constitutionally invalid.
However, you should know that you do not have the right under federal or state constitutions to challenge prior convictions on grounds of “ineffective assistance of counsel.” For those with out-of-state prior convictions who can not attack a “prior DUI” on the grounds of lack of waivers of right to jury trial, right to confront witnesses, and privilege against self-incrimination, unless there is evidence that these procedural requirements were in place at time of your guilty plea.
If you do not comply with the five-day notice requirement or you don’t produce the evidence required the court has the option of hearing your motion at the time of sentencing on your current case instead of continuing your case, except that, if good cause is shown for the failure to provide notice or produce the required evidence, the court must grant a continuance for a reasonable period. Additionally, the prosecution may appeal, before judgment, an order striking a separate conviction according to People v. Kirk (1992) 7 CA4th 855, 858 – 860, 9 CR2d 270.