P0300 Code on a Cadillac: Random/Multiple Cylinder Misfire Detected (Cadillac Guide)

P0300 on a Cadillac is GM's "Engine Misfire Detected" code. It means the engine computer saw misfires it could not pin on one cylinder, or saw them on several cylinders at once. On a Cadillac that covers a lot of ground. One code can come from a Northstar V8, a 3.6L V6, a 2.0L turbo four, a supercharged CTS-V or a 6.2L Escalade, and GM's bulletins for each of those engines point somewhere different. The surprise: on most Cadillac misfire bulletins, GM's first step is not "replace the coils." It is a coolant-dye borescope check on the 3.6L V6, a valve-movement check on Escalade lifters, or a leak-down test on the 2.0T. This page is the hub for our Cadillac misfire guides. Start here, then use the cylinder-specific pages (P0301–P0306) once you know which cylinders are involved.

What Does P0300 Mean on a Cadillac?

The engine control module (ECM) watches crankshaft speed through the crankshaft position sensor. Each firing cylinder gives the crankshaft a small push. When a cylinder fails to fire, the crank slows for an instant, and the ECM counts a misfire. GM's monitor tracks counts for every cylinder. When the misfires are spread across cylinders, or the ECM can't assign them cleanly, it sets P0300. When one cylinder is clearly at fault it also sets that cylinder's code, P0301 through P0308. GM's own bulletins usually list P0300 together with the single-cylinder codes for that reason.

A misfire comes down to one of four things: no spark, the wrong amount of fuel, no compression (valves, rings, pistons, lifters), or something in the cylinder that shouldn't be there, such as coolant or oil. P0300 tells you that one of those happened, but not which one. The misfire counts per cylinder in your scan data are what start to narrow it down. For the GM-wide explanation, see our P0300 GM diagnosis guide.

Which Cadillac Engines Can Set P0300

Every gasoline Cadillac sold with OBD-II can set P0300. Which single-cylinder codes can follow it depends on the cylinder count. Cylinder deactivation also matters, because GM's bulletins keep pointing at the cylinders that deactivate.

The Lyriq, Optiq and other Cadillac EVs have no engine, so they never set P0300.

Read the Pattern Before You Replace Anything

The single most useful thing on your scan tool is the per-cylinder misfire count. GM's bulletins sort themselves by pattern, and so should your diagnosis:

• One cylinder far ahead of the rest — go to that cylinder's guide: P0301, P0302, P0303, P0304, P0305 or P0306. Each one covers where that cylinder sits on each Cadillac engine and the GM bulletins that name it.
• Cylinders 2 and 5 on a Gen 2 V6 — those are GM's AFM cylinders. GM points to the AFM oil control valve or the switching rockers, not ignition.
• Cylinders 1, 4, 6 and/or 7 on an Escalade or LT4 — those are GM's AFM cylinders on the small-block V8. GM points to lifters.
• Every cylinder on one bank — look at what the bank shares. GM has documented a failing high-pressure fuel pump lifter that shows up as bank-1 misfires on the 2018 Escalade (PIP5642), and a failed PCV oil separator causing bank-one misfires on the CT6 4.2L (PIP6013).
• Only on a cold start, then gone — on the 3.6L V6 that's GM's coolant-in-the-cylinder pattern (18-NA-115). On the 6.2L, look at P050D (PIP5498M).
• Only on deceleration, every cylinder — GM's PIP5264 for 3.6L, 3.0L and 2.8L V6 Cadillacs points to belt or pulley debris or worn engine mounts. It's a false misfire from crankshaft speed noise, not a real combustion problem.

What GM Has Documented for P0300 on Cadillacs

3.6L and 3.0L V6: Coolant in the cylinder on a cold start

Bulletin 18-NA-115 (latest July 2024 version) covers the ATS (2013–2019), CTS (2010–2019), CT5 3.0L (2020–2025), CT6 (2016–2020), SRX (2010–2016), XTS (2013–2019), XT5 (2018 and later) and XT6 (2020 and later). GM describes a cold-start misfire or rough idle that "always" occurs "on one or two cylinders" and goes away once the engine warms up. The cause is porosity in the cylinder block at the liner-to-deck face, which lets coolant into the cylinder. GM's test is coolant dye, then a pressure test on a cold-soaked engine, then a blacklight borescope through the plug hole. If the porosity is confirmed, GM says the engine must be replaced. Normal pitting on the deck face is not the cause. GM's earlier PIP4959 versions warned that engines replaced for normal pitting would be returned as non-defective.

Gen 2 V6 (LGX, LGW, LGY): Rockers, lash adjusters and noise

21-NA-278 covers ATS, CTS, CT5, CT6, XT5 and XT6 Gen 2 V6 engines that have a tick or rattle with P0300 or P0301–P0306. GM lists spongy stationary hydraulic lash adjusters, damaged switching roller finger followers, damaged camshaft actuators or locating slots, and a left-bank timing chain tensioner gasket that doesn't seal. GM asks for a sound recording before anything is taken apart.

2.0L turbo four (LTG): Coils, pistons and pre-ignition

On 2019 ATS and CTS 2.0T engines, 19-NA-246 blames talc powder inside the coil boot. It has lower insulation strength than dielectric grease, so it can lead to arcing and carbon tracking. GM warns that "a prolonged misfire condition can result in piston damage." Service update N192281810 had dealers inspect those same 2019 engines for carbon tracking and, where found, replace all four plugs and coils. For 2013–2018 ATS, 2014–2018 CTS and 2016–2018 CT6 2.0T engines, PI1178F describes P0300 with low compression in one cylinder caused by a crack in the piston between the compression rings. The 2013 ATS 2.0T also had customer satisfaction program 14591 for piston damage from pre-ignition. It ran until December 31, 2016, so it has passed for practical purposes.

Escalade and V-series V8s: Lifters

15-06-01-002O covers 2015–2020 Escalade and 2016–2019 CTS-V engines with P0300 and a tick. The causes are an AFM lifter that is collapsed or stuck, internal locking-pin damage from oil aeration, a lifter stuck in its bore, or a bent pushrod. On the 2021 Escalade 6.2L L87 built September 1, 2020 through March 31, 2021, 23-NA-043 covers collapsed or separated lifters with P0300–P0308. GM's replacement rule depends on mileage: all lifters and guides on both banks under 16,000 miles, the affected bank only above that. Separately, safety recall 25V-274 covers certain 2021–2024 Escalade and Escalade ESV 6.2L engines for connecting rod or crankshaft defects that can lead to engine failure. If your misfire comes with a knock, check that recall first.

Older Cadillacs

NHTSA's index lists older GM documents we could only see summarized:

• A 2003 emission recall (03005) for 2002–2003 DeVille, Eldorado and Seville misfires caused by lost signal from the PCM to the ignition coils
• Bulletin 01616 for P0300 on the rear-drive Northstar in the 2004 SRX and XLR
• Bulletin 010100 for intermittent P0300–P0306 on the 2000 Catera

We list them as corroborated only.

Symptoms of P0300 on a Cadillac

• Check engine light, flashing when the misfire is severe enough to harm the catalytic converter
• Rough idle, shake at a stop, or a stumble when accelerating
• Misfire only on a cold start (3.6L coolant pattern), only under load, or only after an AFM event
• A tick or tap at camshaft speed (lifter or rocker problems on the Escalade and Gen 2 V6)
• Loss of power and fuel economy; a fuel smell from the exhaust
• Companion codes: P050D (cold start rough idle), injector circuit codes, or camshaft correlation codes P0016–P0019 on the Gen 2 V6

Causes and How to Confirm Each

How Is P0300 Diagnosed on a Cadillac?

1. Identify the engine by RPO code (glovebox label or VIN decode). The same model name can carry four different engines.
2. Save freeze-frame data and the misfire counts for each cylinder before clearing anything. GM's Technical Assistance misfire template (PIP5628G) asks dealers for exactly this.
3. Classify the pattern: one cylinder, AFM cylinders, one bank, cold-start only, or deceleration only.
4. Swap coils and plugs on the worst cylinder and re-test. On 2025 Escalade L87/LT4 and CT5-V Blackwing, GM's PIP6073 asks for this coil swap before anyone condemns an injector.
5. Test injectors with GDS2 balance or AFIT rather than replacing them on suspicion.
6. Run compression and leak-down tests on any cylinder that won't respond. On the CT6 4.2L, GM's 19-NA-253 relative compression test sorts mechanical from non-mechanical misfires.
7. Run the engine-specific checks: the dye-and-borescope test on the 3.6L, valve-movement checks on Escalade AFM lifters and Gen 2 V6 rockers, or a leak-down on the 2.0T.
8. Check your VIN for open recalls and bulletins, then verify the repair under the same conditions that set the code.

Parts and Cost

GM Documents That List P0300 on Cadillac Models

Have a dealer check your VIN for open recalls and bulletins. The check is free, and it is more reliable than any article, including this one.

What Other P0300 Pages Get Wrong

• "Replace all the coils and plugs." On a Cadillac with GM's documented lifter, rocker, piston or coolant faults, new coils won't fix anything. Do the swap test first.
• "P0300 means random, so it isn't one cylinder." GM sets P0300 alongside single-cylinder codes all the time. Check the per-cylinder counts.
• "Cylinder deactivation cylinders are the same on every GM engine." They are 1, 4, 6, 7 on the small-block V8, 2 and 5 on the Gen 2 V6, and 2, 3, 5, 8 on the CT6 4.2L. The L87 can deactivate any cylinder.
• "A cold-start misfire that clears up is harmless." On the 3.6L that's exactly the pattern GM ties to coolant entering the cylinder.
• "Swap the injector." In PIP6073 (2025 Escalade and CT5-V Blackwing), GM says injectors returned for this concern were inspected and no trouble was found. The coil was the problem. Test before you replace.

Frequently Asked Questions

Can I drive my Cadillac with P0300?

With a steady light and a mild misfire, a short careful drive to a shop is usually fine. A flashing check engine light means the misfire is severe enough to overheat the catalytic converter. Avoid hard acceleration and get it checked promptly.

Why does my Escalade only misfire with a ticking noise?

A tick at camshaft speed with misfires on cylinders 1, 4, 6 or 7 matches GM's AFM lifter bulletins (15-06-01-002O and PIP4568S). The check is whether the valves on that cylinder actually move.

My XT5 misfires only on cold mornings. What should I ask for?

Ask the dealer about bulletin 18-NA-115. It covers a cold-start misfire on one or two cylinders caused by coolant entering through block porosity, confirmed with dye and a borescope.

Does a Northstar get P0300 for the same reasons?

Partly. Coils, plugs and fuel delivery apply to every engine. The Northstar has no cylinder deactivation, so the AFM lifter and rocker bulletins don't apply to it. The GM Northstar misfire documents we found are older, and we could only see them summarized.

Will a tune-up fix P0300 on my 2.0T ATS?

Possibly, if the cause is a carbon-tracked coil boot or a worn plug. GM also documents cracked pistons on the 2.0T (PI1178F), so check compression on any cylinder that keeps misfiring after new plugs and coils.

Which page should I read next?

If one cylinder's misfire count stands out, read that cylinder's guide. If the misfires are on one bank or the AFM cylinders, the sections above tell you which GM bulletin to bring to your service advisor.