P0300 on Buick
Random/Multiple Cylinder Misfire Detected
P0300 on Buick vehicles indicates random/multiple cylinder misfire detected. Au7o has documented this code across 7 Buick models — most commonly on Cascada, Enclave, Encore. P0300 means the engine computer detected misfires occurring randomly or across multiple cylinders rather than in one specific cylinder. A misfire is when a cylinder fails to ignite its fuel-air mixture properly, which the computer senses through small fluctuations in crankshaft speed. Because it's not isolated to one cylinder, the cause is usually something that affects the whole engine — like fuel, air, or ignition system problems — rather than a single coil or plug. Persistent or heavy misfiring wastes fuel, runs rough, and can damage the catalytic converter, which is why a flashing check engine light should be taken seriously. Typical repair costs on Buick range from $300 to $4,500, depending on the specific model and root cause.
Common Causes of P0300
- •Worn or fouled spark plugs (across cylinders)
- •Vacuum or intake air leak
- •Weak fuel pump, clogged fuel filter, or low fuel pressure
- •Failing ignition coils or worn spark plug wires
- •Dirty or faulty mass airflow (MAF) sensor
- •Clogged or dirty fuel injectors
- •Faulty crankshaft/camshaft position sensor
- •Low compression or EGR/PCV system faults
P0300 on Buick by Model
Buick Cascada(1 issue)
- Cascada 1.6L Turbo (Opel SIDI) Timing Chain & Carbon Buildup2016-2019
The German-built Buick Cascada uses the Opel 1.6L SIDI turbo (A16XHT family). Same engine family is documented for timing chain stretch on Opel Astra K and Insignia. Direct-injection design also leads to intake valve carbon buildup typically by 70,000-100,000 miles, causing misfire and rough running.
Buick Enclave(1 issue)
- Stretched/Worn Timing Chain on 3.6L V62008-2013
The 3.6L (and 2.8L) high-feature V6 in 2008-2013 Enclaves is prone to timing chain stretch and worn chain guides/tensioners, sometimes appearing as early as 40,000-60,000 miles. As the chain elongates, valve timing drifts, triggering misfires and a rattle at idle/startup; if a chain jumps a tooth it can bend valves and cause catastrophic engine damage. GM acknowledged the defect (occurring even with regular oil changes) and issued Special Coverage Adjustment #11340C extending the chain warranty to 10 years/120,000 miles on affected engines.
Buick Encore(2 issues)
- Encore 1.4L Turbo (LUJ/LUV) Timing Chain Stretch2013-2022
The 1.4L Turbo LUJ (2011-2015) and LUV (2016+) in Encore — and shared Chevy Cruze/Sonic/Trax — develops timing chain stretch typically between 80,000-130,000 miles. Cold-start rattle, then misfire codes, then risk of chain skip. Same engine family used in Opel Astra J (Astra Adam Mokka — see prior Opel issues).
- Engine Stalling and Sudden Power Loss While Driving (Early Models)2013-2015
The 2013-2015 Encore generated hundreds of NHTSA complaints for engine stalling and abrupt loss of power, including incidents at highway speed where the vehicle decelerated unexpectedly. Owners report rough idle, hesitation, misfires, and the "engine power reduced" message, often traced to sensor faults, throttle body issues, or turbo-related underboost. Multiple reports note the problem recurring even after throttle body or sensor replacement, creating a serious safety hazard in traffic.
Buick LaCrosse(1 issue)
- LaCrosse 3.6L LLT/LFX Timing Chain Stretch2010-2016
The GM 3.6L LLT (2007-2011) and LFX (2012+) "High Feature" V6 in LaCrosse, Enclave, Acadia, Traverse, CTS, Cadillac SRX, and many others suffers timing chain stretch typically between 80,000-150,000 miles. Root cause is oil-related — original OLM intervals (up to 12,000 miles) starved the chain of fresh oil. Excessive oil consumption (LLT also has a known consumption issue) accelerates wear.
Buick LeSabre(1 issue)
- LeSabre 3800 V6 Lower Intake Manifold (LIM) Gasket Leak1995-2005
Same 3800 V6 LIM-gasket failure mode as Park Avenue — extremely widespread in 1995-2005 LeSabres. Coolant migrates past degraded plastic-and-rubber gasket into the valley, contaminating engine oil. Owners commonly first notice low coolant with no visible leak; by the time milky oil appears, bearings may already be damaged.
Buick Park Avenue(1 issue)
- Park Avenue 3800 V6 Lower Intake Manifold (LIM) Gasket Leak1995-2005
The 3800 Series II (and early III) V6 in Park Avenue, LeSabre, Riviera, Regal, Lucerne — and shared Pontiac Bonneville/Grand Prix, Olds 88/LSS, Chevy Monte Carlo/Impala — suffers infamous lower intake manifold gasket failure. Plastic intake material softens under coolant exposure (especially Dex-Cool); gasket erodes and leaks coolant into the lifter valley, mixing with oil. Catastrophic if undetected.
Buick Regal(1 issue)
- Carbon Buildup on Intake Valves (Direct Injection)2011-2017
Like other GM direct-injected engines, the Regal's 2.0T and 2.4L DI engines accumulate carbon deposits on the back of the intake valves because fuel no longer washes the valves clean. Over tens of thousands of miles this causes cold-start misfires, rough idle, hesitation, and reduced power and economy. It is a well-documented owner complaint on the turbo cars in particular.
Looking for P0300 on a different make?
View P0300 across all makes →Frequently Asked Questions
What does P0300 mean on Buick?▼
P0300 stands for "Random/Multiple Cylinder Misfire Detected." P0300 means the engine computer detected misfires occurring randomly or across multiple cylinders rather than in one specific cylinder. A misfire is when a cylinder fails to ignite its fuel-air mixture properly, which the computer senses through small fluctuations in crankshaft speed. Because it's not isolated to one cylinder, the cause is usually something that affects the whole engine — like fuel, air, or ignition system problems — rather than a single coil or plug. Persistent or heavy misfiring wastes fuel, runs rough, and can damage the catalytic converter, which is why a flashing check engine light should be taken seriously. On Buick specifically, this code is documented across 7 models.
What causes P0300 on Buick vehicles?▼
Common causes on Buick: Worn or fouled spark plugs (across cylinders), Vacuum or intake air leak, Weak fuel pump, clogged fuel filter, or low fuel pressure, Failing ignition coils or worn spark plug wires, Dirty or faulty mass airflow (MAF) sensor. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0300 on a Buick?▼
Repair costs on Buick range from $300 to $4,500, depending on the specific model and root cause.
Which Buick models have P0300 documented?▼
Au7o has documented P0300 on 7 Buick models: Cascada, Enclave, Encore, LaCrosse, LeSabre, Park Avenue, Regal.