It is important that you do not correct the error during the auction or indicate in any way that a mistake has been made.
What you do next depends on whether your partnership wins the Contract or is Defender
• If you (not your partner who provided the misinformation) become the declarer, (or dummy) you must call the Director before play commences on the hand and also explain to your opponents that your partner has given a mistaken explanation.
• If your opponents win the contract then, as defender, you must call the Director after the hand has been played.
As always, let the Director decide if any further action is necessary.