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1999 Chevy Silverado 4.8L P0355 Code: Won't Idle, No Throttle Response After Crank Sensor Replacement

Model: 1999 Chevy Silverado Fault Code: P0355 Posted: 2016-08-28 12:44

My 1999 Chevrolet Silverado LT with a 4.8L engine recently developed an idle issue after replacing the crankshaft position (CKP) sensor located above the starter motor. The truck now fails to idle properly at startup, showing no response from the gas pedal. The check engine light is on and a P0355 code is present. I'm concerned that the sensor replacement may have caused additional issues. Could there be other underlying problems related to the crankshaft position or ignition system? I've already replaced the CKP sensor with a new one, but the symptoms persist—low idle (around 200–300 RPM) and no throttle response even after reinstallation. Any insight into what might have gone wrong during this repair process?

Related fault codes
P0355
Comments (5)
Anonymous 2016-08-28 13:31

Why was the crankshaft position sensor (CKP) replaced? Did you perform a CKP relearn procedure? Are there any other diagnostic codes besides P0355? A simple test would be to swap coil #5 with coil #1—observe if the P0355 code follows. If it does, this may indicate a faulty coil or wiring issue rather than a sensor problem.

Anonymous 2016-08-29 00:03

I initially had a check engine light and used a code reader that showed a P0366 code (though I later realized this was due to poor vision at night). The truck ran fine when cold in the morning, but after warming up, it lost power below 20 mph. At speeds above 35 mph, it felt hesitant with reduced responsiveness. After returning home and cooling down, I disconnected the negative battery cable and removed two bolts from the starter. I then pulled out the three-wire harness and swapped components—reinstalled everything, but the truck wouldn't start at all; it only cranked over. I replaced the sensor with the original one and it started up with a low idle (around 200–300 RPM) and no throttle response, lasting about two minutes. After swapping back to a new sensor with warranty, I didn’t disconnect the battery this time—trucks started but again showed low idle and no gas pedal response. What went wrong during this component swap?

Anonymous 2016-08-29 10:26

Was the original code actually P0366? Please post all diagnostic codes and vehicle conditions. Does your scanner read manufacturer-specific codes (e.g., P0999 and above)? Did you perform a CKP relearn after replacement? If so, did your scanner support this function? Note: Is the vehicle stock configuration with no modifications?

Anonymous 2016-08-30 22:37

Yes, the vehicle is stock. The code is P0355—not P0366 as I mistakenly reported earlier due to late-night blurry vision. My scanner only reads basic OBD-II codes and does not support relearn procedures. There are no additional codes detected at this time. Due to limited time, I took the truck to a Chevrolet dealership. I hope they provide honest and fair repair pricing. I’ll update with their diagnosis by this week. Thank you for your help.

Anonymous 2016-08-31 20:30

Hello—after speaking with the dealership, they stated that there is play in the crankshaft, which is causing the P0355 code. This seems unusual since both the old and new sensors were intact and showed no damage. No relearn was performed during repair. The truck still lacks throttle response and has no pedal feedback. I’m not sure if the crankshaft teeth are worn or if there’s debris present on the sensor surface. The issue persists even after replacing the sensor with a new one. This raises concerns about whether the root cause is mechanical rather than electrical.