Can a HELOC lender get a deficiency judgment?

IF they elect to give up their right to conduct a Trustee's Sale, and proceed with a traditional court case to obtain a judgment on the debt and an order for foreclosure, then yes a HELOC lender generally can get a deficiency, unless the HELOC was used for the purchase of the property.

In California we do not have traditional mortgages and foreclosures, exactly, though we have things that behave very similarly.  When you take out a loan secured by real property you give a "Deed of Trust."  That document is recorded and gives the trustee, usually a title company, the right to sell the property and do other things on behalf of the lender if the loan is not paid.  This is what most people call their mortgage.  When the loan is not paid, the lender can direct the trustee to sell the property at auction after following various notice requirements and waiting prescribed times for the borrower to cure the default.  That Trustee's Sale is what most people call a "foreclosure" and even we lawyers often call a "non-judicial foreclosure."

The Trustee's Sale is much more expeditious than the alternative, which is to file a traditional law suit to enforce the debt, and for an order that the property be sold, the proceeds be applied to the debt, and any deficiency be declared a personal judgment against the debtor.  In addition, the Trustee's Sale is made without any right of redemption or other rights and remedies that apply to the judicial foreclosure.  So there are great advantages to the lender, both in terms of time and superior rights against the borrower, to using the Trustee's Sale.  In exchange for granting those advantages, however, the law takes away the right to obtain a deficiency if the auction does not bring in enough to cover the debt.

The lender does, however, have the right to proceed down both paths for a long time; only shortly before the auction or trial does the lender have to elect a remedy.  Once they elect one, however, they cannot later proceed with the other.  So if the lender holds the Trustee's Sale, the right to deficiency is cut off, even if there is a pending suit for a deficiency.

One other limitation on deficiencies exists, though it does not often apply to HELOCs.  In order to curb speculation in real estate in the 1800's, a law went on the books in California that precludes a purchase-money lender from obtaining a deficiency judgment.  The idea was that with the law in place no one would lend more than the property would bring at a Trustee's Sale auction.  So with loans limited to the realistic value, people would not be able to bid up properties beyond their real value.  Well we all know how well that worked in a world where appraisers were unaccountable, and lenders bundled up their loans and sold them as soon as they made them, never taking any risk that the value wasn't there.

But I digress.  In any case, the law is still there.  HELOCs are not often purchase money loans, but sometimes people take out a second or even third loan when they buy a house in order to cover most or all of the down payment.  Sometimes those loans are in the form of a HELOC and the buyers just draw 100% of the line in the escrow to cover the purchase.  In that case the HELOC lender would not be able to obtain a deficiency judgement (though I would have to research whether or not the lender would have to know the HELOC draw was being used for purchase money, or if the rule applies regardless of that).