So every now and then my car keeps throwing these codes

p0420-catalyst effiency
p0117-coolant temp sensor low input

the second one is the one I am having a problem with it was on for like a month and wouldn't let me clear it with my scan gauge then i swapped an exhaust manifild gasket and it went away for like 100miles then came back.Then I put my car on the dyno to do some tuning and it went away again for like another 100miles came back again but this time it allowed me to clear it with my scan gauge.

my question would be how is it that everytime i do something completely unrelated the code clears itself weather the battery is disconnected or not but returns a few days later?

also what could cause the temp sensor to be recieving a low input?

do you think it is the actual sensor or the wiring?

 

How is your emanage wired? PnP harness or Hardwired?

 

hardwired

 

i'd bet on the wiring but honestly, I have no clue...

 

Triple check your wiring. I know someone who had a similar situation and wiring was furbar'd.

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