GMC Sierra: Common Codes & Fixes
Real-world diagnostic data for the GMC Sierra. These are the codes techs see most often. Tap any code for the full vehicle-specific fix and the exact part.
66 codes have specific fixes for the GMC Sierra
B0028 On GM trucks, B0028 usually traces to the driver-side front impact sensor bolted to the radiator support. B0029 GM B0029 normally points to the passenger-side front impact sensor on the radiator support. B0100 Airbag ECU malfunction is often caused by a faulty front impact sensor or corroded connector under the bumper. B1200 B1200 (climate control panel) on GM trucks is almost always caused by a failed HVAC control head. C0020 C0020 (ABS pump motor circuit) on GM trucks is usually a failed pump motor inside the ABS hydraulic unit. C0035 Left front wheel speed sensor failure is extremely common on GM trucks. C0040 Right front wheel speed sensor -- same failure mode as the left side (C0035). C0045 Left rear wheel speed sensor on GM trucks is mounted on the rear axle housing. C0050 Right rear wheel speed sensor -- same diagnosis and repair as C0045 left rear. C0110 C0110 (pump motor circuit malfunction) on GM trucks is similar to C0020 -- the ABS pump motor or its driver circuit is failing. C0131 C0131 (master cylinder pressure sensor) on GM trucks indicates the internal pressure sensor in the ABS hydraulic unit is out of range. C0161 C0161 (brake switch circuit) on GM trucks is the #1 cause of ABS and traction control lights. C0300 Rear speed sensor malfunction on GM trucks usually points to the vehicle speed sensor (VSS) on the transfer case (4WD) or transmission… C0561 C0561 (ABS disabled) on GM trucks is an informational code -- it means ABS is disabled due to another code. P0102 MAF sensor circuit low input. P0103 MAF sensor circuit high input. P0110 The IAT sensor on the 5.3L is located in the intake air duct. P0121 TPS range/performance problem. P0201 Cylinder 1 injector circuit fault. P0202 Cylinder 2 injector circuit fault. P0217 Engine coolant overtemperature. P0219 Engine overspeed detected. P0222 GM full-size trucks with the 5.3L/6.0L: check the TAC module ground stud on the driver-side fender. P0300 Active Fuel Management (AFM/DFM) lifter failure. P0301 Cylinder 1 is an AFM cylinder on the 5.3L V8. P0302 Cylinder 2 is NOT an AFM cylinder on the 5.3L, so this is less likely to be lifter-related. P0303 Cylinder 3 on the 5.3L is NOT an AFM cylinder, so lifter failure is less likely. P0304 Cylinder 4 is an AFM cylinder on the GM 5.3L V8. P0306 Cylinder 6 is an AFM cylinder on the GM 5.3L V8. P0307 Cylinder 7 misfire on GM V8s is most often a worn spark plug or a failed ignition coil on that cylinder. P0327 Bank 1 knock sensor low input. P0330 Bank 2 knock sensor malfunction. P0332 Bank 2 knock sensor circuit low input. P0336 Crankshaft position sensor performance issue. P0351 Coil 1 circuit fault. P0352 Coil 2 circuit malfunction. P0432 On GM trucks, the main underbody converter on Bank 2 degrades over time, especially with oil consumption from AFM (Active Fuel… P0450 The fuel tank pressure sensor on GM trucks is integrated into the EVAP canister vent solenoid assembly. P0451 GM trucks use a fuel tank pressure sensor integrated into the fuel pump module. P0453 The fuel tank pressure sensor reads high voltage when the connector corrodes from road salt exposure. P0454 P0454 indicates an intermittent signal from the fuel tank pressure (FTP) sensor. P0460 GM trucks have a known issue with the fuel level sensor contacts wearing through the resistor card. P0485 Corroded cooling fan connector at the fan shroud -- water and road salt gets in. P0496 On GM trucks with P0496, the purge solenoid fails in the open position. P0501 The vehicle speed sensor is in the transfer case on 4WD models and the transmission tail shaft on 2WD. P0520 The oil pressure sensor/switch on the GM 5.3L Gen IV engine is a known failure item. P0562 System voltage low is almost always a failing alternator or corroded battery cable on GM trucks. P0563 System voltage too high (above 16V) indicates a failed voltage regulator inside the alternator overcharging the battery. P0601 PCM internal memory checksum error on GM trucks is often caused by low battery voltage during a cold start. P0616 Corroded starter relay or control circuit on GM trucks. P0843 P0843 means the transmission fluid pressure (TFP) sensor/switch 'A' circuit is reading HIGH voltage -- typically an open circuit, a… P2118 Voltage drop on throttle body ground circuit -- corroded G101 ground stud behind driver-side headlight. U0001 High speed CAN bus fault typically indicates a wiring problem between control modules. U0073 U0073 (control module communication bus A off) on GM trucks means the high-speed GMLAN bus is not terminating. U0100 Lost communication with ECM/PCM is a common GM code. U0101 Lost communication with TCM (Transmission Control Module). U0121 Lost communication with ABS module. U0131 Lost communication with power steering control module. U0140 Lost communication with BCM (Body Control Module). U0155 Lost communication with the instrument panel cluster (IPC). U0184 GM truck U0184 often appears after a radio swap to an aftermarket unit without the proper CAN bus interface. U0401 Invalid data received from ECM/PCM means the PCM is communicating on the CAN bus but sending corrupt data. U0402 U0402 (invalid data from TCM) on GM trucks means the ECM sees the transmission control module reporting but with bad data. U0422 GM truck U0422 often indicates the BCM is sending odd data because of a low battery or bad ground. U0672 U0672 lost communication with Front Control Module is often caused by a blown fuse or a BCM-to-FCM CAN bus short. U3125 On GM trucks U3125 typically indicates the transfer case or 4WD ECU has dropped off the bus.
Frequently Asked Questions
What are the most common check engine light codes on a GMC Sierra?
The most commonly reported OBD-II codes for the GMC Sierra include B0028, B0029, B0100, B1200, C0020. Each code indicates a specific issue -- tap any code above for the full diagnostic breakdown.
How much does it cost to fix a check engine light on a GMC Sierra?
Repair costs vary by code. Many GMC Sierra fixes like gas cap replacement, sensor cleaning, or spark plug changes are under $50 in parts and can be done at home. More complex repairs like catalytic converter or transmission work can run $500-$2,000+ at a shop.
Can I drive my GMC Sierra with the check engine light on?
It depends on the code. A steady check engine light usually means you can drive short distances safely. A flashing check engine light means stop driving immediately -- continued driving can cause serious engine damage. Scan the code first to know what you are dealing with.