Dodge Repair Questions? Ask a Mechanic for Answers ASAP
Hi There, This is Clay, I'm a certified master automobile technician with 30 years of automotive repair and diagnostic experience.
P0440 most commonly sets for the Natural Vacuum Leak Detection (NVLD) assembly on this vehicle. The NVLD is located next to the EVAP canister in front of the fuel tank. A voltmeter and a hand vacuum pump are required to test the NVLD. It would also be a good idea to have the EVAP and intake smoked checked for any vacuum leaks. The NVLD device is designed with a normally open vacuum switch, a normally closed solenoid, and a seal, which is actuated by both the solenoid and a diaphragm. The normally open vacuum switch will close with about 1" hg in the evaporative system.
Without converters I'd expect the system to be running rich, there is no change in the exhaust gases for the dowstream O2 to make comparisons with. Any and all vacuum leaks will cause a rich running condition. Basically the PCM adds more fuel to compensate for the additional intake of air not regulated and monitored at the throttle body. That being said I'd say the vacuum leak may also be a cause for the converter failures.
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