P0302 on Mercedes-Benz: How to Diagnose & Fix
Cylinder 2 Misfire Detected
1 Mercedes-Benz model · 2 documented issues · 1 critical · $300-$7,000 repair
P0302 on Mercedes-Benz by model: symptoms, diagnosis and fix
The 1.3L turbocharged direct-injection M282 engine (co-developed with Renault, used in A180/A200) suffers carbon deposit buildup on the intake valves and ports because direct injection does not wash the valve backs with fuel. On urban/short-trip duty cycles deposits accumulate from roughly 60,000 miles, causing rough running and hesitation.
Common Symptoms
- Rough idle
- Hesitation at 1500-2500 rpm
- Reduced fuel economy
- Flat/sluggish acceleration
- Misfire under load
How to Fix
Walnut-shell media blasting of the intake valves/ports, typically recommended every ~50,000-60,000 miles. Using top-tier fuel, periodic intake/induction cleaning, and avoiding constant short trips slows buildup. A quality oil meeting the MB spec helps limit blow-by contribution.
Sources for this issue (2)
On the M260 2.0L four-cylinder turbo used in the A220, A250 and A35 AMG (and the CLA250, GLA250, GLB250), the exhaust valve seat rings and valve guides can wear prematurely so that the exhaust valves no longer seal. The result is a loss of compression on one or more cylinders, rough idle and misfire codes, and in advanced cases a rattling/ticking top end. Mercedes-Benz USA acknowledged the defect in August 2023 with an Emission Warranty Extension (document MC-10241534-0001, TSB 'ELW-ExhaustValve') covering 2019-2022 A-Class, CLA, GLA and GLB with the M260, extending coverage on the exhaust valve system to 15 years/150,000 miles. Owners on MBWorld and A-Class Club report dealers replacing the complete cylinder head under the extension, and UK A35 owners have documented loss-of-compression diagnoses on the same engine. This is separate from the M282 1.3L intake carbon issue: the M282 is a different (Renault co-developed) engine and does not share this valve-seat defect.
Common Symptoms
- Rough idle and misfire, especially cold
- Check engine light with cylinder misfire codes
- Low compression on one or more cylinders in a leak-down test
- Loss of power, hesitation under load
- Ticking or rattling noise from the cylinder head
How to Fix
Free repair within 15 years/150,000 miles for US 2019-2022 cars under the MBUSA exhaust-valve warranty extension: the dealer performs a leak-down/compression test and replaces the cylinder head assembly (valves, seats, guides) as needed; owners who paid for this repair before the extension can claim reimbursement with documentation. Outside the US or outside the extension, a replacement cylinder head on the M260 is a $4,000-$7,000 job, so any persistent P0300-P0304 misfire on a low-mileage M260 should be compression-tested before spending money on plugs and coils.
Sources for this issue (5)
- Mercedes-Benz Emission Warranty Extension MC-10241534-0001 (exhaust valve system, 15 yr/150,000 mi)tsb
- Warranty Repair - Cylinder Head! - MBWorld.org (GLB250, M260)forum
- Cylinder Head Extended Warranty M260 Engine - A-Class Clubforum
- A35 AMG loss of compression - MBClub UKforum
- 2019 Mercedes-Benz A220 TSBs (incl. ELW-ExhaustValve, Aug 3 2023)tsb
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 Mercedes-Benz?
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 Mercedes-Benz it is documented across 1 model: A-Class.
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 Mercedes-Benz?
Published repair estimates on Mercedes-Benz range from $300 to $7,000 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.