Truck got hard starting and is throwing this code and sometimes a PO336 code? Any Suggestions!

 

P0513-SKIM INVALID KEY ERROR **weird that code links me to this P0513 instead of the p0531***

WHEN MONITORED
Key on

SET CONDITION
Invalid Key Code received from SKIM Module

POSSIBLE CAUSES

• General network error
• Key not programmed
• Incorrect key
• Incorrect VIN IN ECM or SKIM
• Loss of communication between ECM and SKIM

 

P0336-CRANKSHAFT POSITION (CKP) SENSOR SIGNAL

WHEN MONITORED
With the key on.

SET CONDITION
The voltage detected at the Crank position sensor is below a calibrated value.

POSSIBLE CAUSES

• CKP sensor
• (K24) Signal circuit open
• (K853) 5-volt supply circuit open
• (K975) Return circuit open
• (K24) Signal circuit shorted to (K975) return circuit
• (K853) 5-volt supply circuit shorted to (K975) return circuit
• (K24) signal circuit shorted to (K853) 5-volt supply circuit
• (K24) signal circuit shorted to ground
• (K853) 5-volt supply circuit shorted to battery negative
• Intermittent condition
• ECM

 

If the RPMs on your tachometer bottom out (your tachometer reads zero) while driving, it's your crankshaft position sensor. It causes hard starting if it's on the fritz because it initiates the fueling cycle from the injection pump.