P0300 on a 2017 GMC Acadia Denali

P0300 is a generic OBD2 powertrain code for random or multiple cylinder misfire. Unlike P0301 through P0308, it does not point to one specific cylinder, so the cause can be ignition, fuel, air, sensor, or mechanical.

Not your vehicle? See general P0300 info.

Most common causes on the 2017 GMC Acadia Denali

Ranked from 639 NHTSA owner complaints filed for this vehicle.

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1
Timing chain stretch / camshaft position actuator wear
High severity
This engine has a documented pattern of camshaft and timing chain wear; one owner had the camshaft and timing chain replaced and still retained a check-engine light, and another pulled cam/VVT-related codes (P0010/P0016/P0018/P0507) alongside a rough-running, shuddering engine - drifted cam timing directly causes misfire.
Reported in 2 NHTSA complaints
Parts:timing chain camshaft position actuator
2
Mass airflow/manifold pressure (MAF/MAP) sensor fault
Medium severity
One owner had the MAP sensor replaced for a persistent check-engine light with the car "shuddering" at idle and under light acceleration, tracing back to the intake air pressure measurement system - an inaccurate air reading skews fueling enough to cause rough running/misfire.
Reported in 1 NHTSA complaint
Parts:MAP sensor MAF sensor
3
Excessive oil consumption fouling spark plugs
Medium severity
One owner reported the engine burning through oil so fast it needed monthly top-offs; oil pulled past worn rings/seals into the combustion chamber fouls spark plugs and disrupts combustion, contributing to misfire.
Reported in 1 NHTSA complaint
Parts:spark plugs
4
High-pressure fuel pump mechanical failure
High severity
One owner's high-pressure fuel pump mounting bolt sheared off inside a cylinder, damaging the pump and spraying oil through the engine bay - a catastrophic fuel-delivery failure of this kind causes severe misfire before the engine loses power entirely.
Reported in 1 NHTSA complaint
Parts:high-pressure fuel pump
5
Carbon buildup on intake valves
Medium severity
This direct-injection 3.6L engine has no port-injection fuel wash over the intake valves, so carbon accumulates over time and disrupts airflow and mixture at the valve, a well-known contributor to random misfire on this engine family.
Common cause
6
Worn or fouled spark plugs
Medium severity
Eroded electrodes or fouling widen or foul the spark gap, causing intermittent misfire that often worsens with mileage.
Common cause
Parts:spark plugs
7
Failing ignition coil(s)
Medium severity
A weak or intermittently shorting coil misfires its cylinder, often worse when hot or under load.
Common cause
Parts:ignition coil
8
Vacuum or intake leak
Low severity
Unmetered air entering after the airflow sensor leans the mixture out enough to cause rough idle and random misfire.
Common cause

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These causes are aggregated from NHTSA owner complaints and general repair knowledge — this is not a diagnosis. P0300 on your car still needs shop confirmation before any repair.

Common symptoms

Flashing or steady check engine light
Rough idle
Shaking under acceleration
Loss of power
Fuel smell from exhaust

What to check before replacing parts

Scan for cylinder-specific misfire codes

Look for: A companion P0301–P0308 pins the misfire to one cylinder — start there. P0300 with no cylinder code points at something hitting several at once: fuel pressure, a large vacuum leak, or timing.

Inspect the spark plugs and coils

Look for: Pull the plugs: black/sooty = rich, oily = oil intrusion, white/blistered = lean or overheating, cracked porcelain or an out-of-spec gap = replace. Then swap a coil to another cylinder — if a cylinder-specific code follows the coil, the coil is bad.

Check fuel trims for a vacuum leak

Look for: High positive short- and long-term trims (worst at idle, improving as RPM rises) mean unmetered air is getting in. Smoke-test the intake and listen for hissing.

Verify fuel pressure

Look for: Compare running/cranking pressure to the vehicle spec. Low or dropping pressure starves multiple cylinders and reads as a random misfire — suspect the pump, filter, or regulator.

Compression / leak-down test if ignition and fuel check out

Look for: A cylinder 15%+ below the others, or leak-down hissing from the intake (intake valve), exhaust (exhaust valve), or oil filler (rings), means the misfire is mechanical — not a swap-in part.

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Matching symptoms

Car Runs Rough Flashing Check Engine Light