Catalog

MERCEDES-BENZ/SMART A1121840025 OIL FILTER

Product Specifications

Product quality
OEM Equivalent Grade
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Wholesale price USD $0.87
Wholesale price CNY ¥6
bolt MOQ (Minimal order)
500 pcs
local_shipping Production time
40 days
package_2 Shipping Weight: —
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MERCEDES-BENZ/SMART A1121840025
MERCEDES-BENZ/SMART 5086301AA
MERCEDES-BENZ/SMART 0001803109
MERCEDES-BENZ/SMART 05102905AA
Overview & Operating Principle
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The OIL FILTER is a full-flow filtration element positioned in the engine lubrication circuit between the oil pump and the main oil gallery, removing metallic particles, carbon deposits, and combustion soot from the oil before it reaches the crankshaft bearings, camshaft journals, and valve train components. The filter medium is a pleated synthetic or cellulose paper element with a filtration rating of 15–25 microns for standard service filters and 10–15 microns for extended-service synthetic-compatible filters. Two internal valves are critical to correct operation: the anti-drain-back valve retains oil in the filter housing when the engine is stopped, ensuring immediate oil pressure on restart without a dry-start period; and the bypass valve opens at a calibrated differential pressure (typically 0.7–1.5 bar) to maintain oil flow to the engine if the filter element becomes blocked, preventing oil starvation at the cost of unfiltered oil circulation.

This unit — MERCEDES-BENZ/SMART A1121840025 — is manufactured to OEM-equivalent specifications: thread size and pitch, gasket outer diameter and material, filter medium grade and pleat count, anti-drain-back valve elastomer compound, and bypass valve opening pressure are matched to the original part. Supplied as a direct replacement for standard fitment. Available wholesale from 0.87 USD, MOQ 500 pcs, production lead time 40 days.

The oil filter is a service item replaced at every oil change — typically every 10,000–15,000 km for mineral oil and 15,000–20,000 km for full synthetic, or annually, whichever comes first. A filter that has reached capacity loads with soot and metallic debris until the bypass valve opens, after which unfiltered oil circulates through the engine. Never extend the oil change interval beyond the OEM specification to save cost — the cumulative bearing wear from contaminated oil far exceeds the cost of timely service.

Symptoms & Diagnostics
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Oil pressure warning light illuminated on startup that extinguishes after a few seconds — a failed anti-drain-back valve has allowed oil to drain back from the filter into the sump overnight; the engine runs without oil pressure until the pump refills the filter, causing dry-start bearing wear on every cold start.
Oil pressure warning light that remains on at idle but extinguishes at higher RPM — a heavily contaminated filter operating in bypass mode at low pump output pressure; the bypass valve opens under higher pump pressure at elevated RPM, masking the fault; replace the filter and oil immediately.
Oil leak at the filter base — the filter gasket is not seating correctly due to a double-gasket installation (old gasket left on the housing when the new filter was fitted) or incorrect torque; a filter gasket leak will lose oil rapidly under operating pressure.
Increased engine noise on cold start — valve train rattling or hydraulic tappet noise caused by delayed oil pressure buildup from a failed anti-drain-back valve or an incorrectly specified filter with insufficient anti-drain-back valve retention force for the mounting orientation.
Dark, heavily contaminated oil on the dipstick well before the service interval — the filter bypass valve has been open for an extended period, allowing unfiltered oil to circulate; carbon and metallic particles are accumulating in the oil rather than being captured by the filter medium.
Metal particles visible in the drained oil or on a magnetic drain plug — the filter has been operating beyond its service life or in bypass mode, allowing bearing or wear metal to recirculate through the engine rather than being captured; investigate the source of the metallic debris before refitting a new filter.
Logistics & Customs
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International HS Code
8421.23
EAEU Customs Code (TN VED)
8421 23 000 0
Typical Net Weight
Country of Manufacture
China
Standard MOQ
500 pcs
Production Lead Time
40 days
Always verify the exact 8-digit or 10-digit subheading with your customs broker for the destination country, as tariff schedules and duty rates vary by jurisdiction.
Installation Tips
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  1. Drain the engine oil completely before removing the filter — removing a full-flow filter with oil in the engine will spill a significant volume of hot oil. Position a drain tray under the filter before loosening it, as residual oil in the filter housing will drain when the filter breaks the seal even with the sump drained.
  2. Remove the old filter using an oil filter wrench and inspect the filter seating face on the engine block for the old gasket — the most common oil change error is leaving the old rubber gasket on the block and threading the new filter over it, creating a double-gasket condition that will blow out under oil pressure and cause a major oil leak within seconds of startup.
  3. Clean the filter seating face on the engine block with a clean cloth, removing all traces of old oil and gasket material. Inspect the seating face for nicks or corrosion that could prevent the new gasket from sealing; light surface rust can be cleaned with a fine abrasive cloth.
  4. Apply a thin film of clean engine oil to the new filter gasket before installation — this lubricates the rubber gasket during tightening, prevents the gasket from tearing or rolling, and ensures an even seating contact around the full circumference of the housing face.
  5. Tighten the filter by hand until the gasket contacts the seating face, then tighten a further three-quarter turn — do not use a filter wrench for final tightening as overtightening distorts the gasket and makes the filter extremely difficult to remove at the next service. The standard rule is hand-tight plus three-quarter turn for spin-on filters; cartridge filters use a housing cap torqued to OEM specification (typically 15–25 Nm).
  6. Install the new OIL FILTER (MERCEDES-BENZ/SMART A1121840025), refill with the correct grade and quantity of engine oil, start the engine and check immediately for leaks at the filter base — the oil pressure warning light should extinguish within 3–5 seconds; if it remains on beyond 10 seconds, shut the engine down immediately and investigate before restarting.
Tools: oil filter wrench (correct size for this application), drain tray, clean cloth, funnel for oil fill, torque wrench for cartridge filter housing cap.
Frequently Asked Questions
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Can the oil filter be changed without changing the engine oil, or must both be replaced together?
The oil filter must always be replaced simultaneously with the engine oil — never one without the other. A new filter fitted with old degraded oil will be rapidly contaminated by the suspended particles and acids already present in the oil, shortening its effective service life to a fraction of its rated capacity. Conversely, fresh oil circulated through a loaded old filter will pick up the accumulated contaminants from the filter medium and become contaminated within a short period. ok.parts supplies oil filters at wholesale MOQ from 0.87 USD per unit for workshop and fleet stocking alongside oil supply programmes.
Does the engine require any reset or adaptation after an oil and filter change?
No ECU adaptation is required after an oil and filter change on most vehicles. However, the oil service interval reminder displayed on the instrument cluster must be reset using the vehicle's on-board service menu or a scan tool — the procedure varies by manufacturer but typically involves holding a specific button combination during ignition-on. On vehicles with oil quality sensors (e.g. certain BMW and Mercedes-Benz models), the sensor recalibrates automatically after the first drive cycle with fresh oil and does not require manual reset.
How does the OEM-equivalent aftermarket unit compare to the genuine OEM part?
OEM-equivalent units in this catalogue replicate the current OEM design geometry and material specification. Quality is verified against OEM cross-reference data. When ordering in bulk, confirm with our team that the specification matches the latest OEM revision for your application.
Is white-label or custom packaging available for wholesale orders?
Yes. ok.parts works directly with the manufacturing facility and can accommodate neutral white-label packaging or fully branded packaging with your company logo, part numbers, and barcode. Minimum order quantities and lead times for custom packaging may differ from standard stock. Contact the team via the inquiry form to discuss your specific requirements.
Frequently Replaced Together
PartReason for Combined Replacement
Engine Oil
Grade and specification per OEM requirement		The oil filter and engine oil are a single service item — replacing one without the other negates the benefit of the service. Always specify the correct oil grade (viscosity and specification, e.g. 5W-30 ACEA C3) for the engine and operating climate, and fill to the correct level on the dipstick before starting.
Oil Drain Plug Washer
Aluminium or copper crush washer, M12–M18		The drain plug crush washer seals the sump drain hole and must be replaced at every oil change. A reused washer that has already been compressed will not seal reliably under the drain plug torque, causing a slow oil seep that typically goes unnoticed until oil has dropped significantly below the minimum level.
Cabin Air Filter (Pollen Filter)
OEM ref. varies by vehicle		The cabin air filter shares the same replacement interval as the engine oil and filter service on most vehicles. Combining both replacements in a single workshop visit reduces the total service time and ensures complete scheduled maintenance is performed in one appointment, reducing the risk of the cabin filter being overlooked between dedicated service visits.