Help protect your engine from damaging detonation with the Standard Ignition Ignition Knock (Detonation) Sensor KS221. It installs as a direct-fit replacement across a range of 1.8L four-cylinder and 2.7L/3.0L V6 Audi and Volkswagen models, including the 2001-2006 Audi A4, 2001-2006 Audi A4 Quattro, 2002-2005 Audi A6, 2003-2004 Audi A6 Quattro, 2003-2005 Audi Allroad Quattro, and 2000-2005 Volkswagen Passat.
A knock sensor picks up the high-frequency vibrations produced by abnormal combustion (knock/detonation) and sends a voltage signal to the engine control module, which can then adjust ignition timing. If a failed knock sensor is the cause of a stored knock-related trouble code, this unit replaces it.
- Wide response range: designed to respond to knock frequencies up to 1000 Hz to accommodate shifts in engine knock across varied operating conditions.
- 100% tested: every unit is checked with an accelerometer vibration test for reliable operation.
- Monitored output: an automated data-acquisition system verifies appropriate voltage output at the specified frequency range.
- Bolt-on design: oval plug-in connector with three male blade terminals; mounting hardware is not included.
Some listed applications use two sensors per engine, so confirm the quantity your vehicle needs in the Buyer's Guide tab. Country of origin: Italy.
Interchange: 06C905377 · S8821 · SU6306 · DKS661 · Manufacturer part number KS221
Fitment: 2001-2006 Audi A4 [L4-1.8L]; 2002-2005 Audi A4 [V6-3.0L]; 2001-2005 Audi A4 Quattro [L4-1.8L]; 2002-2006 Audi A4 Quattro [V6-3.0L]; 2002-2005 Audi A6 [V6-3.0L]; 2003-2004 Audi A6 Quattro [V6-2.7L]; 2002-2004 Audi A6 Quattro [V6-3.0L]; 2003-2005 Audi Allroad Quattro [V6-2.7L]; 2000-2005 Volkswagen Passat [L4-1.8L].
This part cross-references / interchanges with the following part numbers:
Frequently Asked Questions
What does this knock sensor do?
It detects the high-frequency vibrations of engine knock/detonation and sends a voltage signal to the engine control module, which can then adjust ignition timing.
Will the KS221 fit my vehicle?
It is a direct-fit replacement for the listed Audi A4, A4 Quattro, A6, A6 Quattro, Allroad Quattro and Volkswagen Passat applications with 1.8L, 2.7L or 3.0L engines. Check the Buyer's Guide tab.
How many sensors do I need?
It depends on the engine. Some listed applications use two knock sensors, while others use one. Confirm the quantity your specific vehicle requires in the Buyer's Guide tab.
Is mounting hardware included?
No. Mounting hardware is not included. Consult the vehicle service information for the correct fasteners and whether they may be reused.
What numbers does this part interchange with?
It cross-references 06C905377, S8821, SU6306 and DKS661. The manufacturer part number is KS221.
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