Cal. Civ. Proc. Code § 1283.8

The award shall be made within the time fixed therefor by the agreement or, if not so fixed, within such time as the court orders on petition of a party to the arbitration. The parties to the arbitration may extend the time either before or after the expiration thereof. A party to the arbitration waives the objection that an award was not made within the time required unless he gives the arbitrators written notice of his objection prior to the service of a signed copy of the award on him.