A common problem with the SR20DET is the CAS cover gasket is often damaged or has expanded with age. Nissan don't sell the CAS cover gasket on its own which means to replace this part you'd need to buy a complete new CAS at a cost of $500 We have made our own replacement specific to the Nissan SR20DET RWD motors to ensure that dirt and debris stays out of your CAS and keeps your engine running optimally.