The result dashed the hope for the local favourite's much-anticipated duel against Pankaj Advani, who scored an easy 3-0 win against Manish Jain of West Bengal to make the quarters.
Haria posted a break of 137 to go one up 150-7 against his PSPB colleague who was quick to bounce back and level posting a break of 148.
But Haria reigned supreme in the third set and did not give Kothari any chance for a 151-0 win before sealing the issue in the fourth set with a 150-141 win.
Pankaj Advani (PSPB) beat Manish Jain (WB) 150(99)-8, 151(151)-0, 151(142)-11; Dhvaj Haria (PSPB) beat Sourav Kothari (PSPB) 150 (137)-7, 4-152(148), 151(110)-0, 150(65)-141 (88); Rupesh Shah (PSPB) beat Nikhil Ghadge (RSPB) 150(140)-64, 150 (93,51)-17, 150 (150)-0; Dhruv Sitwala (PSPB) beat Rafath Habib (RSPB) 150(120)-121(80), 150(90)-98, 150(58,92)-06; Siddharth Parikh (RSPB) beat Alok Kumar (PSPB) 151(82)-8, 105-150,150-110,12-150(91), 150(150)-5; Brijesh Damani (PSPB) beat Devendra Joshi (PSPB) 3-275(51)-151, 151(78)-113(51), 151(65)-29, 119-150 (86), 151(51)-27; B Bhaskar beat Vishal Madan 86-151 (80), 150 (57)-76, 151(55,81)-136 (67), 152 (63,37)-87(52); Jaiveer Dhingra b Ashok Shandilya 150-141, 150-41, 51-150, 150-106.