MAN 51274210163 SWITCH ASSY OIL
Product Specifications
Product quality
OEM Equivalent Grade
On request
bolt MOQ (Minimal order)
1 pcs
local_shipping Production time
30 days
package_2 Shipping Weight:
—
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Application (cross references) 2
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| MAN | 51274210163 |
| MAN | 51274210263 |
Overview & Operating Principle
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The SWITCH ASSY OIL is an engine oil pressure switch or sensor threaded into the main oil gallery — typically at the cylinder block, oil filter housing, or cylinder head — that monitors the pressurised oil circuit and signals the driver or the ECU when oil pressure drops below the minimum threshold required for adequate hydrodynamic lubrication of the crankshaft main bearings, connecting rod bearings, and camshaft journals. Two principal designs are in current production and serve different functions: the simple oil pressure warning switch is a normally-closed or normally-open single-contact device containing a diaphragm and a calibrated spring-loaded contact that opens or closes at a fixed pressure threshold — typically 0.3–0.5 bar — switching the instrument cluster warning light circuit directly; this design provides only a binary low-pressure warning without any pressure level information. The variable-output oil pressure sensor — also called a sender unit — uses a piezoresistive or strain gauge element bonded to a steel diaphragm that deflects proportionally under oil pressure, producing a continuous resistance or voltage output that the instrument cluster uses to drive an analogue oil pressure gauge needle across its full scale, or that the ECU uses to monitor oil pressure for engine protection and oil change reminder functions. On modern engines both types may be present simultaneously — a warning switch for the dashboard warning light circuit and a sender for the gauge — each threaded into a separate port in the oil circuit.
This unit — MAN 51274210163 — is manufactured to OEM-equivalent specifications: thread size and pitch for the oil gallery boss, switching pressure threshold or resistance-pressure characteristic curve, diaphragm pressure rating, connector pinout, housing material and corrosion treatment for the engine bay thermal environment, and sealing washer type are matched to the original part. Supplied as a direct replacement for standard fitment. Available wholesale from 0.18 USD, MOQ 1 pcs, production lead time 30 days.
Oil pressure switches and sensors fail through diaphragm perforation from metal particles circulating in degraded oil — a perforated diaphragm allows oil to contact the electrical contacts or fill the sensor bore, causing the warning light to illuminate permanently or the gauge to read incorrectly; through contact corrosion in the warning switch design that causes the contacts to remain closed regardless of actual pressure, producing a spurious low-pressure warning; and through thread seal failure that produces an oil leak at the sensor base. A confirmed oil leak at the sensor body combined with a warning light requires immediate attention — a leaking sensor in an underbonnet position can drip oil onto the exhaust manifold, creating a fire risk.
Symptoms & Diagnostics
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Oil pressure warning light illuminated at idle after a warm-up period — light extinguishes at higher RPM — confirm actual oil pressure with an external mechanical gauge connected to the same gallery port; if actual pressure is within specification, the switch threshold has drifted or the diaphragm is fatigued; if actual pressure is genuinely low, the pump or bearing clearances require investigation before attributing the warning to a faulty sensor.
Oil pressure warning light permanently illuminated from the moment of engine start regardless of RPM — the most common warning switch failure presentation; the switch contacts are stuck closed from corrosion or the diaphragm has perforated and oil has reached the contacts; confirm by disconnecting the sensor connector — if the light extinguishes when the connector is unplugged, the sensor has failed closed; if the light remains on with the connector unplugged, the warning circuit has a wiring fault.
Oil pressure gauge reading permanently at maximum (full-scale) regardless of engine condition — the sender resistance has failed to minimum (near-zero ohms), which the gauge circuit interprets as maximum pressure; confirm by disconnecting the sender connector — the gauge should drop to minimum with the connector unplugged on most instrument cluster designs; if the gauge remains at maximum with connector unplugged, the fault is in the gauge or instrument cluster.
Oil pressure gauge reading permanently at zero or minimum regardless of engine running — the sender resistance has failed to maximum (open circuit), which the gauge circuit interprets as no pressure; confirm oil level and actual pressure with a mechanical gauge before condemning the sender; an engine with genuine zero oil pressure will produce severe knocking from the main bearings within seconds and must not be run.
Oil leak at the sensor body — wet oily residue at the thread engagement zone or dripping from the sensor body — the thread seal washer has failed from overtightening on previous installation or from sensor body corrosion; an oil leak at the sensor in an underbonnet location above the exhaust manifold is a fire risk requiring immediate rectification; clean the area and run the engine briefly to confirm the exact leak source before removing the sensor.
Oil pressure warning light that flickers during cornering, braking, or when the oil level is at or slightly below the minimum mark — the oil is surging away from the pick-up under lateral and longitudinal g-forces, momentarily causing a genuine low-pressure event that closes the switch; this is not a sensor fault — inspect oil level and top up to the correct level; if the flickering continues at correct oil level, inspect the oil pump pick-up screen for blockage.
Logistics & Customs
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International HS Code
9026.20
EAEU Customs Code (TN VED)
9026 20 200 0
Typical Net Weight
Country of Manufacture
China
Standard MOQ
1 pcs
Production Lead Time
30 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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- Verify actual oil pressure with an external mechanical gauge before replacing the sensor — connect a calibrated mechanical gauge to the oil gallery port (temporarily removing the existing sensor) and measure actual oil pressure at idle and at 2,000 RPM; compare against the OEM specification — typically 1.0–2.0 bar at idle and 3.0–5.0 bar at 2,000 RPM; a genuine low-pressure condition requires oil pump, bearing clearance, and oil level investigation before sensor replacement; replacing a sensor when genuine low pressure exists delays diagnosis of a mechanically critical fault.
- Allow the engine to cool before removing the oil pressure sensor — the sensor is threaded into the pressurised oil gallery; removing it from a hot engine releases pressurised oil at operating temperature; on a cold engine the system pressure is zero and oil release is minimal; always confirm the engine has been off for at least 30 minutes before removing the sensor from any gallery position.
- Use the correct sensor socket — typically a thin-wall hex socket of the exact sensor body hex size — oil pressure sensors have a smaller hex than an equivalent-thread spark plug and require a dedicated sensor socket; a standard hex socket that contacts the sensor body edges rather than the full hex faces rounds the hex corners and may crack the sensor body; never use adjustable pliers on a sensor hex.
- Apply PTFE tape or specified thread sealant to the sensor thread before installation only where required by the OEM specification — many oil pressure sensors seal on a copper or aluminium crush washer at the sensor base and do not require thread sealant; applying PTFE tape to a crush-washer-sealed sensor prevents the washer from seating correctly and may cause an immediate oil leak; confirm the sealing method from the OEM parts data before applying any thread preparation.
- Torque the new sensor to the OEM specification using a torque wrench — typically 15–25 Nm; undertightening allows oil to seep past the thread seal; overtightening cracks the sensor body housing or strips the aluminium thread in the engine block gallery boss, requiring Helicoil repair; the OEM torque value is particularly important for sensors with crush-washer sealing where the correct washer compression is critical for sealing.
- Install the new SWITCH ASSY OIL (MAN 51274210163), reconnect the wiring connector, start the engine and immediately confirm the oil pressure warning light extinguishes within 3 seconds of start; confirm the gauge reads in the normal operating range; check for oil leaks at the sensor thread with the engine at operating temperature and pressure; clear any stored oil pressure fault codes with a scan tool before returning the vehicle to service.
Tools: thin-wall oil pressure sensor socket (application-specific hex size), calibrated mechanical oil pressure gauge for actual pressure verification, torque wrench (15–25 Nm), PTFE tape where thread sealing is specified, OBD-II scanner for fault code clearance.
Frequently Asked Questions
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How can a faulty oil pressure sensor be confirmed as the cause of a warning light before the engine is condemned for low oil pressure?
The oil pressure warning light should never be dismissed as a sensor fault without first verifying actual gallery pressure with a mechanical gauge. The diagnostic sequence is: check oil level first — a level at or below minimum can produce genuine low pressure warnings at idle; if the oil level is correct, connect a mechanical gauge to the gallery port and run the engine — actual pressure within the OEM specification (typically ≥1.0 bar at idle when warm) confirms the sensor has failed rather than the lubrication system; actual pressure below specification confirms a genuine lubrication fault requiring immediate engine shutdown and investigation of the oil pump, pump pick-up screen, and bearing clearances. Never assume a warning light is caused by a sensor fault on an oil pressure circuit — the consequences of ignoring a genuine low-pressure warning are engine destruction. ok.parts supplies oil pressure switches and sensors at wholesale MOQ from 0.18 USD per unit.
What is the difference between an oil pressure warning switch and an oil pressure sender, and can they be substituted for each other?
An oil pressure warning switch is a binary on-off device that closes or opens its single contact at a fixed threshold pressure to illuminate the dashboard warning light — it has one electrical terminal (the switch body grounds through the engine block). An oil pressure sender is a variable-resistance or variable-voltage transducer that produces a continuously varying output proportional to actual oil pressure, driving an analogue gauge needle — it has one or two signal terminals and a separate ground. The two types are not interchangeable: a warning switch connected to a gauge circuit produces a gauge that reads either zero or maximum with nothing in between; a sender connected to a warning light circuit produces a light that stays on or off depending on whether the sender resistance happens to be above or below an arbitrary resistance threshold. Always confirm whether the required replacement is a switch (for a warning light) or a sender (for a gauge) from the vehicle's wiring diagram before ordering.
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
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| Part | Reason for Combined Replacement |
|---|---|
| Engine Oil and Filter Grade and specification per OEM requirement | An oil pressure sensor that has failed from metal particle perforation of its diaphragm indicates the oil circuit contains abrasive metallic debris. These particles will perforate the new sensor's diaphragm at the same rate as the original if the contaminated oil is not replaced. Always perform a complete oil and filter change simultaneously with pressure sensor replacement when diaphragm perforation is the confirmed failure mode — not just top-up, but a full drain and refill with fresh oil of the correct specification. |
| Oil Pressure Gauge or Instrument Cluster OEM ref. varies — where gauge remains incorrect after sender replacement | If the oil pressure gauge continues to read incorrectly after confirmed sender replacement and verified correct wiring, the fault has moved to the gauge element or instrument cluster circuit. On older vehicles with electromagnetic gauge movements, the gauge coil may have an open-circuit winding that mimics a sender failure; on modern CAN-bus cluster designs, the displayed oil pressure value is calculated by the cluster ECU from the sender voltage — a cluster that has stored an incorrect calibration value may read incorrectly despite a correct sensor output. |
| Oil Filter Housing Gasket or O-Ring Application-specific — where sensor is mounted in filter housing | On many modern engines the oil pressure sensor is threaded into the oil filter housing rather than the engine block. Accessing the sensor for replacement disturbs the filter housing and its sealing gasket or O-ring. Replace the filter housing gasket simultaneously with the sensor to prevent an oil leak at the housing-to-block joint — a leak that would require a second filter housing removal to correct. |