I have a 2004 impala 3.4 that’s having start issues. Long story short my car started having a slow crank 2 months ago. Took it to a mechanic he was 90% sure it was the crankshaft sensor he replaced that and put a new harmonic balancer on. That didn’t solve the issue (turns out it just needed a battery) paid $340 for the sensor and balancer for nothing but of course I wasn’t getting a refund. Now the car has started having issues again it stalled on me randomly. Check engine light came on. While accelerating the car was sputtering. Had car scanned for codes P0336 came back for the crankshaft sensor. Anyone know why it could be doing this with the new sensor? Part is still under warranty so I’m taking it back to the shop Tuesday but worried this guy might not know what he’s doing. Could the sensor be faulty?