2000 S40 Can't clear Leak Detection Pump codes

[loowho]

I have a 2000 S40 that I purchased used. About a year ago, the car threw the Leak Detection Pump codes (ECM-65 and P1449), so I took it to my mechanic to have it replaced. He put on the new part, but then the car started throwing a bunch of other codes. I took it to the Volvo dealer for diagnostics (at my mechanic's recommendation) and it came back with the P1449 code, again. The dealership stated that the LDP my mechanic had put on was a non-working part. I took the car back to my mechanic and he pulled off the new part and replaced it with another new LDP. The check engine light came on again, so I took the car to another mechanic to pull the codes; the LDP codes came up, again. Is there something that my mechanic may have not done when installing the LDP that is necessary for the engine codes to clear? He seemed surprised that my year and model had that part in the first place.
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[jimmy57]

The check valve in the vacuum supply line for the LDP can be a problem. That LDP is not a conventional electric pump. It has a spring pressing on a diaphragm, a vac solenoid, and a position switch for the diphragm. The ecm signals solenoid and the diaphragm lifts and switch closes and ECM cuts off solenoid to create pump strokes. Leakage rate is determined by time the diaphragm takes to go down via spring pressure. If the vacuum supply is not good then the ECM sets odd codes. The check valve gets obstructed and vacuum supply is not great enough to lift diaphragm fully so the expected operation doesn't occur.

[loowho]

Thank so much for this information. I'm going to have him check the vacuum supply line. Thanks again!