P0302 on Alfa Romeo: How to Diagnose & Fix
Cylinder 2 Misfire Detected
2 Alfa Romeo models · 2 documented issues · 1 critical · $500-$1,200 repair
P0302 on Alfa Romeo by model: symptoms, diagnosis and fix
On 2017-2018 Giulia sedans with the 2.0L turbo four (and 2018 Stelvio), an engine misfire can dump unburned fuel into the exhaust and overheat the catalytic converter. The excess heat can damage nearby engine-compartment wiring and components, which FCA identified as both an engine-compartment fire risk and a stall risk. Owners typically see a check-engine light, rough running and a temporary loss of power, and some report a burning smell, before the stall or fire. This is distinct from the low-pressure fuel pump stall campaign: the root cause here is combustion misfire plus engine-control-module calibration, and the recall centers on updated control software, with inspection and parts replacement if required.
Common Symptoms
- Check engine / malfunction indicator lamp illuminated
- Rough running or shaking at idle
- Temporary loss of engine power
- Burning smell from the engine bay
- Engine stalls without warning
- Smoke or fire from the engine compartment
How to Fix
For an included VIN, recall UA4/18V636 provides a dealer inspection and PCM software update at no charge. The dealer records a scan report and follows FCA's STAR process if P0420, P0171, P2096, P2270 or P0299 is present. The owner notice includes part inspection and replacement when required; consequential damage can require FCA approval through the recall or warranty process. Ask the dealer to determine the covered repair before paying for parts. The estimated visit repair time in the owner notice is about one hour, with additional check-in time.
Call to confirm they can assess your vehicle and perform the stated work. Search results do not confirm qualification, eligibility or coverage.
Sources for this issue (3)
The 2.0L GME turbo four is direct injected, so no fuel washes over the back of the intake valves. Crankcase vapour routed through the PCV system bakes onto the valve heads and forms hard carbon deposits that disrupt airflow and seal quality. What makes the Stelvio case notable is how early it appears: Stelvio and Giulia forum members report being sent for walnut blasting at Alfa's direction at roughly 6,000-6,500 miles because of cold-start misfires, an order of magnitude sooner than the 75,000-125,000 mile window typical of other direct-injection engines. Symptoms are worst on a cold start and often clear once the engine warms, which is why the condition is frequently dismissed on a test drive. This is a 2.0L issue and should not be merged with the 2.9L V6 Quadrifoglio's separate intake-side story.
Common Symptoms
- Rough idle and misfire on cold start that smooths as the engine warms
- Check engine light with cylinder misfire codes
- Hesitation or stumble under light throttle
- Reduced fuel economy
- Loss of low-end power
How to Fix
The real fix is mechanical cleaning - walnut shell blasting of the intake ports and valve faces with the intake manifold removed. Chemical induction/fuel-system services sold at dealers do not remove hardened deposits from the valve backs on a direct-injection engine and are not a substitute. Expect roughly $500-$1,200 at an independent specialist, more at a dealer, and budget for new intake manifold gaskets. Where misfires appear under warranty, dealers have performed the cleaning under warranty. Mitigation between services: use the specified oil, change it on a short interval, and consider a catch can to reduce vapour reaching the valves.
Sources for this issue (3)
P0302 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0302 mean on a Alfa Romeo?
P0302 stands for "Cylinder 2 Misfire Detected." This code means the engine computer has detected a misfire specifically in cylinder 2, meaning that cylinder isn't completing combustion properly on some firing events. The computer watches tiny variations in crankshaft speed to spot when a cylinder fails to fire, and a misfire means the air-fuel mixture isn't igniting correctly — usually from a spark, fuel, or compression problem in that cylinder. You may feel a stumble, rough idle, shaking, loss of power, or a flashing check-engine light, and persistent misfires can damage the catalytic converter. Because it names a single cylinder, the fault is often a component serving just cylinder 2, like its coil, plug, or injector. On Alfa Romeo it is documented across 2 models: Giulia, Stelvio.
What are the most common causes of P0302?
The most common causes of P0302 are: Worn or fouled spark plug (cylinder 2), Failed ignition coil or coil-on-plug (cylinder 2), Clogged or faulty fuel injector (cylinder 2), Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt/bent valve, head gasket), Damaged spark plug wire or boot (if equipped), Carbon-tracked or cracked coil/plug causing spark loss, Faulty PCM/ECM driver (rare). The specific cause varies by vehicle.
How much does it cost to fix P0302 on a Alfa Romeo?
Published repair estimates on Alfa Romeo range from $500 to $1,200 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0302 on a different make?
View P0302 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.