I was testing out a chipped ECU and it throws 2 codes:

#20- ELD code

#54 - Crankshaft Speed Fluctuation sensor - Open or short in CKF sensor circuit, defective CKF sensor circuit

20 isn't important but how import is #54??

What's the disadvantage of running with the check engine light on??

 

Oh yeah, the stock ecu doesn't throw a code. Just the chipped one.

 

54 isnt that important either, i ran with that code for awhile with no noticable effects.

 

Cool. Thanks.