P0300 on a 2017 GMC Acadia

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

Ranked from 701 NHTSA owner complaints filed for this vehicle.

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1
Timing chain/camshaft phaser wear (3.6L LGX)
High severity
Two complaints on this engine describe a faulty camshaft and timing chain diagnosed after check-engine and drivability complaints, with cam-position/crank-cam correlation codes (P0010/P0016/P0018) retrieved alongside the misfire-type symptoms - a well-known wear pattern on this V6 that throws off valve timing enough to cause misfires.
Reported in 2 NHTSA complaints
Parts:timing chain camshaft phaser
2
High-pressure fuel pump/mechanical fuel delivery failure
High severity
One complaint describes the bolt connecting the high-pressure fuel pump to the cylinder shearing off, causing sudden loss of power and engine damage - an abrupt fuel-delivery failure that will produce severe misfire symptoms before complete failure.
Reported in 1 NHTSA complaint
3
Low cylinder compression from oil consumption/worn rings
High severity
Multiple owners report heavy oil consumption on this engine; low ring sealing reduces cylinder compression and can present as a misfire.
Reported in 1 NHTSA complaint
4
Worn or fouled spark plugs
Low severity
The most common general misfire cause; check for excessive gap wear or carbon fouling, especially on vehicles overdue for plug service.
Common cause
Parts:spark plugs
5
Failing ignition coil(s)
Medium severity
A weak or intermittently arcing coil produces a repeatable misfire on the same cylinder; swap coils cylinder-to-cylinder to confirm the fault follows the coil.
Common cause
Parts:ignition coil
6
Clogged or leaking fuel injector(s)
Medium severity
A restricted or dribbling injector starves or floods an individual cylinder, producing a repeatable single-cylinder misfire.
Common cause
Parts:fuel injector
7
Vacuum/intake air leak
Medium severity
Unmetered air entering after the MAF causes lean misfire, typically worse at idle; listen for a hiss and check with propane or a smoke machine around intake gaskets and hoses.
Common cause
8
EGR passage/valve fault
Low severity
Excess or improperly timed EGR flow can produce a lean misfire, particularly at idle or light throttle.
Common cause
Parts:EGR valve

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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