P0300 on a 2016 GMC Canyon

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 2016 GMC Canyon

Ranked from 267 NHTSA owner complaints filed for this vehicle.

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1
Damaged crankshaft reluctor ring / position sensor signal fault
High severity
One owner found a section of the reluctor ring's magnetic strip broken off; a damaged reluctor directly corrupts the crank position signal the PCM uses to time spark and injection, a well-known misfire trigger.
Reported in 1 NHTSA complaint
Parts:crankshaft position sensor reluctor wheel/harmonic balancer
2
Diesel high-pressure fuel pump (HPFP) failure (2.8L Duramax)
High severity
On diesel-equipped Canyons, HPFP internal seal failure sends metal debris through the fuel system and can cause rough running/misfire-type symptoms ahead of a catastrophic engine failure.
Reported in 1 NHTSA complaint
Parts:high-pressure fuel pump fuel injector
3
Worn or fouled spark plugs
Low severity
Standard top cause on the gas-engine Canyon (2.5L/3.6L); worn plugs misfire under load first.
Common cause
Parts:spark plug
4
Failing ignition coil
Medium severity
An intermittent coil produces a load- or heat-sensitive single- or multi-cylinder misfire.
Common cause
Parts:ignition coil
5
Clogged or leaking fuel injector
Medium severity
A dirty injector under- or over-fuels a cylinder enough to misfire, especially at idle.
Common cause
Parts:fuel injector
6
Vacuum or intake leak
Medium severity
Unmetered air leaning one or more cylinders past the misfire threshold; smoke-test the intake tract.
Common cause
7
Low cylinder compression
High severity
Worn rings or a valve issue isolated to one cylinder; confirm with a compression or leak-down test.
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