I Have A Code P0420 And A Coolant Leak On Left Side Of Motor. I Changed The Housing But Still Have Leak.has To Set Overnight To Leak Any Ideas.thanks

p0420 is catalyst efficiency low. Usually caused by running rich or burning oil. If it hasn't been on for too long, sometimes a can of BG 44K will clear that up. It's a gamble, but much cheaper than a cat.

As for the leak... where's it coming from? You said you replaced the (water outlet [?]) "Housing", was the coolant coming from there? If it's still coming from there, take it apart, clean everything really good, and put it back together using silicone sealant. Also silicone the pipe that goes in the back of the housing, and use a screw clamp, never reuse a spring clamp if there's any way around it.

thank you. ill check this