A P0455 code indicates a large leak in the evaporative emission control (EVAP) system. This system prevents fuel vapors from escaping into the atmosphere. Recently, after a thermostat, water pump, belt, and pulley replacement, the P0455 code appeared. Further diagnostics, including a gas cap check and purge valve test, ruled out these common culprits. However, manipulating a small 90-degree hose connected to the vacuum pump behind the manifold resulted in a code change to P0244, related to the leak detection pump (LDP).
The shift from a P0455 to a P0244 code after reconnecting the vacuum pump hose suggests a potential connection between the vacuum pump and the EVAP system leak. While a P0244 code often points to a faulty LDP, a malfunctioning vacuum pump could contribute to the issue. A faulty vacuum pump can potentially introduce oil into the LDP, hindering its functionality and triggering a P0244 code. Cleaning the LDP might resolve the issue if oil contamination is the cause.
The current diagnostic process points to either a vacuum pump issue or a compromised connection related to the vacuum pump hose. Further inspection of the vacuum pump, associated hoses, and the LDP itself are necessary to pinpoint the root cause of the large EVAP leak. This includes checking for vacuum leaks, assessing the integrity of the LDP, and inspecting the condition of the vacuum pump.
