Description

Mercury / MerCruiser Quicksilver Knock Sensor — 806612T

The Mercury Quicksilver 806612T Knock Sensor is a genuine OEM engine detonation sensor used on many MerCruiser V6 and V8 gasoline engines. It detects engine knocking or pre-ignition and sends a signal to the engine control module so ignition timing can be adjusted to protect internal engine components.

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Key Specifications

• Part Number: 806612T

• Component Type: Engine knock sensor

• Mounting Location: Engine block water port above oil pan

• OEM Brand: Mercury Marine / Quicksilver

• Cross-Reference: Volvo Penta 3850357, Sierra 18-7677, Crusader R020027

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Compatible Engines / Applications

Commonly used on MerCruiser GM-based marine engines, including:

• 4.3L V6

• 5.0L V8 (305 CID)

• 5.7L V8 (350 CID / 350 MAG)

• 6.2L V8 (377 CID)

Typically found on MerCruiser sterndrive and inboard engines from the late 1980s through early 2000s, depending on serial number range.

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Function

The knock sensor monitors engine vibration to detect detonation (engine knock) during combustion. When knock is detected, the sensor sends a signal to the ECM, which retards ignition timing to prevent damage to pistons, valves, and bearings.

This helps ensure:

• Proper engine performance

• Protection from pre-ignition damage

• Improved engine reliability and longevity

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Symptoms of a Faulty Knock Sensor

A failing knock sensor may cause:

• Engine knock or pinging

• Loss of power or poor acceleration

• Engine fault codes or warning alarms

• Reduced fuel efficiency

Replacing the sensor restores proper engine timing control and detonation protection.

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Fitment Tip:
Always verify compatibility using the engine model and serial number. MerCruiser engines use different knock sensors depending on engine family, ECM version, and ignition system configuration.

OEM parts ship same or next day for fast Canada wide shipping.

Technical Specifications:

• Type: Knock sensor
• Compatible with: Mercury MerCruiser marine engines
• Part Number: 806612T