30 days return. Buyer pays for return shipping. If you use an eBay shipping label, it will be deducted from your refund amount. Policy depends on shipping service.
I chose this ECU for the lifetime warranty. Hopefully, it was flashed with all factory updates; item description did not mention any updates. The ECU came with helpful instructions to reset GM passlock. My only complaint is that no instructions or mention of the crankshaft position relearn required. Without the CKP relearn it runs normally, but MIL indicator remains on due to code P0315. I had to buy an expensive code scanner to perform the CKP relearn.