jmiaebrown

I am hearing a loud tapping noise when I first start up my 2000 s430. Has 137,000 miles on her. Someone told me to check the lifters/valve stems. Can anyone explain what these are or what the problem could be?

Thank you.

my06clk

MAke sure your Catalytic convertors are not shot..BEFORE you go into the engine. THis may be the cause instead

jmiaebrown

Thank you for responding. After 22 views I was loosing hope. I have also been getting a 0400 code every once in a while. Do you think it could be related?

Thanks again.

my06clk

I'm not sure what that code is but I do know that valves are mechanical and not tied to your emissions system so they wont throw any codes.

okc329

a P0400 code indicates a problem with exhaust gas recirculation. Have the operation of your EGR valve checked out. Be sure you get somebody who knows what they are doing. My understanding is that the purpose of the valve is to allow the engine to suck in some exhaust gas at startup to warm up the car more quickly and reduce emissions. That may be why you hear the noise at startup. Maybe the valve is broken internally.