Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.
The cost to diagnose the B0521 GMC code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
The Instrument Panel Cluster (IPC) receives engine RPM information from the Powertrain Control Module (PCM) on a dedicated engine speed input to IPC. IPC also receives engine RPM data on the serial data line. IPC monitors engine RPM output information sent from PCM for an out of range condition. The PCM sets the Diagnostic Trouble Code (DTC) when the IPC detects that the engine RPM is at least 7400 RPM.
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Get the B0521 GMC code diagnosed by a professional: Find a repair shop in your area