Where are knock sensors located?

Knock sensors are typically mounted directly to the engine block or cylinder head, usually one sensor per bank on V engines or a single sensor on inline engines. The exact position varies by vehicle, engine family, and generation.

Knock sensors monitor combustion vibrations and feed data to the engine control unit to adjust ignition timing and prevent detonation. They are designed to withstand high heat and continuous engine vibration, which is why the mounting point is chosen for signal quality and durability.

Common mounting patterns

Most passenger-car engines follow a few standard layouts. The following patterns cover the majority of contemporary engines, but the exact site for your car will be in the service manual.

• Inline-four and other single-bank engines: typically a single knock sensor mounted in the block or cylinder head. It is commonly found on the side of the engine block toward the rear or beneath the intake manifold where it is shielded from direct heat.


• V6, V8 and other multi-bank engines: usually one knock sensor per bank, mounted on the block or cylinder head near the rear or side of the engine (often toward the firewall). Access may require removing intake components or protective covers.


• Other variations: Some specific models mount sensors in the timing-cover area or along the lower sides of the block to simplify wiring routing. The exact boss and hole designation varies by engine family.

In all cases, knock sensors are small, rugged devices threaded into the engine to detect detonation and send data through the wiring harness to the PCM. If a sensor fails, the check engine light can illuminate and timing may be adjusted to protect the engine. Replacement is straightforward for a trained technician, but location can vary widely by vehicle.

Vehicle-specific notes

Placement can vary even within the same manufacturer across model years, so verify with the official service manual or a repair guide for your exact car. VIN-specific diagrams and dealer service bulletins can provide the precise mounting point.

How to locate knock sensors on your vehicle

To locate the actual sensor on your car, follow these practical steps. The steps are general, as exact locations vary by engine family.

• Consult the owner's manual or service manual for the engine section; search for "knock sensor" or "KS." The diagram will show the sensor location on the block or head.


• With the engine off and cool, visually inspect the engine block sides and cylinder heads. Look for a small threaded boss with an electrical connector or harness running to it.


• Check the rear of the engine near the firewall and the lower sides of the block for inline engines, and the rear of each cylinder head or bank for V engines.


• If in doubt, use the VIN to pull up a factory diagram or contact a dealer to confirm the exact mounting point for your model year.

Knowing the exact location aids diagnostics and replacement, but always follow proper torque specs and use the correct sealant and hardware when reinstalling a knock sensor.

Summary

Knock sensors are installed directly on the engine itself—most often in the block or cylinder head. Inline engines typically use a single sensor, while V- and multi-bank engines use one per bank. Exact mounting points vary by model and engine family, so consult your vehicle’s service manual to locate and service KS correctly.

Where are the knock sensors located?

Knock sensors are typically located on the engine block or cylinder head, often positioned between cylinders to pick up vibrations from knocking. They can also be found in specific locations depending on the vehicle, such as underneath the intake manifold or near the starter on the passenger side. 
This video shows how to locate knock sensors on a specific vehicle model: 1mDude We Can Fix ItYouTube · Jun 14, 2022

• Engine block: This is the most common location, as the sensor can directly detect vibrations from the engine. 
• Cylinder head: Another common mounting point to sense engine noise and vibration. 
• Between cylinders: A common placement for a single sensor, which is often positioned centrally on the block to detect vibration from all cylinders. 
• Under the intake manifold: Some vehicles, particularly those with V-shaped engines, will have knock sensors hidden beneath the intake manifold. 
• Near the starter: In some models, especially on the passenger side, the knock sensor is located near the starter, sometimes underneath the exhaust manifold. 
• Driver's side: Some vehicles will have a knock sensor on the driver's side as well, often near the differential. 

This video shows how to replace knock sensors on a specific vehicle model: 53sTRQYouTube · Apr 25, 2023

Can I drive with a bad knock sensor?

You can likely drive a short distance with a bad knock sensor, but it's not recommended for the long term because the engine may not perform optimally and could eventually be damaged. The car's computer will likely enter a default mode, which can lead to reduced performance, decreased fuel economy, and a higher risk of engine damage if you continue to drive it aggressively or for extended periods. You should get the sensor replaced as soon as possible. 
This video explains what happens when you drive with a bad knock sensor: 1mAuto Repair GuysYouTube · Jul 25, 2020
What to expect when driving with a bad knock sensor

• Reduced engine performance: The engine may hesitate, accelerate less crisply, and feel sluggish. 
• Decreased fuel economy: The computer will likely adjust the engine's timing to a more conservative setting, which can lower your gas mileage. 
• Increased emissions: A faulty knock sensor will likely cause your car to fail an emissions test. 
• Potential for engine damage: While not immediate, driving with a bad knock sensor can eventually lead to more serious and costly damage to the engine's components. 

What to do

• Drive cautiously: Avoid aggressive driving, such as rapid acceleration or high speeds, to minimize the risk of damage. 
• Get it fixed: The sensor should be replaced as soon as you can to restore proper performance and prevent potential damage. 
• Consider the cause: A faulty sensor is the most common issue, but in some cases, the problem could be with the computer controlling it, so a diagnosis is important. 

You can watch this video to learn how a knock sensor works: 38sAuto Repair GuysYouTube · Jan 30, 2022

How many knock sensors are in a car?

The knock sensor is installed in the engine block in a location that lets it detect vibrations from the most detonation-prone cylinders. A vehicle may be equipped with one or two knock sensors, depending on engine type (“V”, “in-line”) and number of cylinders.

How much should it cost to replace a knock sensor?

The average cost to replace a knock sensor is between $250 and $350, but this can vary significantly based on the vehicle's make and model, the labor rates in your area, and the cost of the part itself. The part can range from about $20 for aftermarket to over $100 for OEM, while labor can add $150 to $250 or more depending on how difficult the sensor is to access.
 
This video explains the symptoms of a bad knock sensor and its replacement cost: 1mcar PROblemsYouTube · Aug 24, 2023
Cost breakdown

• Parts: Aftermarket knock sensors can cost as little as $20 to $50, while Original Equipment Manufacturer (OEM) parts typically cost over $100. 
• Labor: Labor costs are a major factor and can add $150 to $250 or more. The total labor time can be lengthy if the sensor is in a hard-to-reach spot and requires other parts to be removed first. 
• Total: The final price of $250 to $350 is an average, but it can go higher for more complex jobs. 

Factors that influence cost

• Vehicle make and model: Some vehicles have knock sensors in more difficult-to-access locations, which can drive up labor costs. 
• Labor rates: Hourly rates for mechanics vary by location, affecting the total price. 
• Parts brand: Choosing a more expensive OEM part over an aftermarket one will increase the total cost. 
• Additional repairs: Depending on the vehicle and the diagnosis, other parts like manifold gaskets may need to be replaced at the same time, adding to the overall expense. 

How to save money

• DIY: If you are comfortable with car repair, replacing a knock sensor is a job you can do yourself to save on labor costs, but be sure to take pictures as you go to remember how to reassemble everything. 
• Shop around: Get quotes from different mechanics to compare prices for both parts and labor. 
• Compare parts: Ask your mechanic about the price difference between an aftermarket and an OEM part, and decide if the cost savings of an aftermarket sensor are worth it for your needs.