1999 Chevrolet Suburban 5.7L: P0336 & P0339 Codes Persist, Engine Won't Start After Relearn Attempt
I have a 1999 Chevrolet Suburban with a 5.7L V8 engine. The vehicle has been experiencing severe stalling and hesitation at all speeds—both cold and hot. I replaced the fuel pump and filter, cleaned and inspected all electrical connections, which appear to be in good condition. After removing and inspecting the distributor, I confirmed no signs of severe wear and reinstalled it as originally intended. The engine spins smoothly when cranked, but after replacing the crankshaft position (CKP) sensor, I attempted a relearn procedure. However, the engine will not start—no spark at the plugs, and no fuel delivery is observed. The OBD2 scanner shows persistent codes P0336 and P0339, both related to the crankshaft position sensor. Despite replacing the CKP sensor with a new one, the code persists. The relearn procedure requires engine operation, which currently does not occur. I am frustrated because the sensor is brand-new and installed correctly. I suspect there may be an intermittent signal or wiring issue, especially given that P0339 often indicates a faulty or loose CKP sensor connection. Could this be due to improper installation or a defective part? Any guidance on verifying sensor signals with a scanner (e.g., CKP/CMP offset or sync) would be greatly appreciated.
Were there any diagnostic codes present before removing the distributor or installing the new crankshaft position (CKP) sensor? Your OBD2 scanner should detect all relevant codes, especially in the P1XXX series. Can you check for CKP and CMP sensor offset or synchronization using your scanner? For P0339 specifically, intermittent signals are common—did you install a genuine GM part? Try replacing the old sensor to test if codes appear without it. Also, you mentioned no spark at plugs—can you confirm spark presence at multiple cylinders?