I have codes galore. great.
I have a 99 Civic Si. Thought I had a bent valve, but it was carbon build up...and had the valve replaced last night. Check engine light was on and these were the codes pulled:
P0118 Engine Coolant Temperature Circuit High Input.
P1259 VTEC System malfunction.
P0171 System is too lean.
P0301 Cylinder #1 Misfire or Random Misfire.
P0303 Cylinder #3 Misfire or Random Misfire.
P0304 Cylinder #4 Misfire or Random Misfire.
P0300 Random Misfire.
"what is causing these codes?"