Famous Engine Noise But No Check Engine Light Ideas. Keep in mind that the fault code that caused the light to turn on in the first place is stored in your car’s onboard. Short out pluge wires by disconnecting them one at a time and see if knock goes away if it does then it's cylinder and it may be a rod bearing knock.
If there are no other symptoms, your check engine light may indicate a problem with your computer, a loose gas cap, transmission errors, or problems with your o2 sensor. Web the check engine light can turn on for a number of reasons. A communication problem between the transmission and engine system can also leave the car stuck in limp mode without the check engine light coming on.
