Trouble codes › By vehicle › GMC Sierra 1500
Common check-engine codes on the GMC Sierra 1500
2007-2023
The Sierra shares its engines and common codes with the Chevrolet Silverado: misfires (including lifter failures on Active Fuel Management V8s), oil pressure sensor faults, EVAP and throttle codes.
Most common: P0300, P0521, P0171, P2135, P0449, P0420.
Known problems on the GMC Sierra 1500
- GM V8 oil pressure sensor and screen (P0521) (P0521, P0520, P0524)
- GM V8 AFM/DFM lifter failure (P0300, P0301, P0302, P0303)
P0300 Random/Multiple Cylinder Misfire Detected
P0300 means the engine is misfiring in more than one cylinder, often from worn plugs or coils, a vacuum leak or low fuel pressure.
On the GMC Sierra 1500: Misfires: on 5.3L and 6.2L V8s with Active or Dynamic Fuel Management, a collapsed lifter (with ticking) is a known cause. Rule out plugs and coils first.
P0300: causes, can I keep driving, and what to check first →
P0521 Engine Oil Pressure Sensor/Switch "A" Range/Performance
P0521 means the oil pressure reading doesn't make sense for how the engine is running; check the oil level and have real pressure tested.
On the GMC Sierra 1500: Oil pressure sensor reading wrong: a clogged screen under the sensor is a common cause. Replace the screen with the sensor and confirm real oil pressure.
P0521: causes, can I keep driving, and what to check first →
P0171 System Too Lean (Bank 1)
P0171 means bank 1 is running lean (too much air or too little fuel), most often from a vacuum leak or a dirty MAF sensor.
On the GMC Sierra 1500: Lean codes, often with P0174: intake gaskets on older engines, MAF sensor or vacuum leaks.
P0171: causes, can I keep driving, and what to check first →
P2135 Throttle/Pedal Position Sensor/Switch "A"/"B" Voltage Correlation
P2135 means the two throttle position sensors disagree, so the engine computer limits power; usually a failing throttle body.
On the GMC Sierra 1500: Throttle position correlation: a failing throttle body or corroded connector.
P2135: causes, can I keep driving, and what to check first →
P0449 Evaporative Emission System Vent Valve/Solenoid Circuit
P0449 means there's an electrical fault in the EVAP vent valve circuit.
On the GMC Sierra 1500: EVAP vent solenoid near the tank: dirt and water make it stick.
P0449: causes, can I keep driving, and what to check first →
P0420 Catalyst System Efficiency Below Threshold (Bank 1)
P0420 means the catalytic converter on bank 1 isn't cleaning the exhaust well enough, usually a worn converter, an exhaust leak or a lazy oxygen sensor.
On the GMC Sierra 1500: Catalyst efficiency at higher mileage: fix misfires first.
P0420: causes, can I keep driving, and what to check first →
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Common codes and known problems as widely reported for these model years; your vehicle may differ. Check nhtsa.gov/recalls and ask a dealer about service bulletins for your VIN, and confirm in your service information.