So I have a 2001 Volvo S40 I've changed the boost sensor for the turbo but I'm still getting a 236 po237 code but I have an exhaust leak is that possible that would cause this I just got this vehicle and I've been driving around for a few weeks with no codes and all of a sudden I have codes

 

okay I've changed out the turbo boost valve with a couple of used ones not guaranteed to work but pretty sure they were good what else would cause these codes they come back right away I clear the code should I disconnect the battery after I clear the code thank you

 

If you cleared the code via an OBD2 reader you're done. Disconnecting the battery won't clear the codes from the ECU memory. If the CEL comes back on after viewing and erasing the fault codes, it means the code is being reset and you need to look into the possible causes.