If you don’t object, how can the error be corrected?

At the appellate level, an objection is necessary to show that objector did everything possible to correct the error by alerting the court and opposing counsel of the problem. Such an objection, if sustained, would have the effect of correcting the problem, while an overruled objection may not help at the trial level but at least will protect the record on appeal.

The failure to object and follow through can have fatal consequences to an appeal.

The failure to object and to take all steps necessary to properly follow through with an objection has serious consequences on appeal. It means that the error to which the objection might have been made is waived and cannot be challenged on appeal. “In light of this section [353], questions relating to the admissibility of evidence will not be reviewed on appeal in the absence of a specific and timely objection.” (Leonardini v. Shell Oil Co. (1989) 216 Cal. App.3d 547, 584; Gallant v. City of Carson (2995) 128 Cal.App.4th 705, 710.)

The courts have made exceptions where the record shows that continued objections would be an idle act or the court refuses to rule on the objections, but you must still make a diligent effort to obtain a ruling. (City of Long Beach v. Farmers & Merchants Bank of Long Beach (2000) 81 Cal.App.4th 780, 784-785.)