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BMW 640i xDrive Gran Coupe Knock Sensor Replacement Cost

Know what price you should pay to get your vehicle fixed.

Knock Sensor Replacement
The average cost for a BMW 640i xDrive Gran Coupe knock sensor replacement is between $416 and $545. Labor costs are estimated between $264 and $333 while parts are priced between $152 and $212. Estimate does not include taxes and fees.
Note about price: The cost of this service or repair can vary by location, your vehicle's make and model, and even your engine type. Related repairs may also be needed. Talk with a RepairPal Certified shop to learn which repairs might be right for you.

How does the knock sensor work?

Every time the engine knock sensor notices a vibration, it sends a signal to the engine's computer, reporting how large it was. The engine's computer is programmed to expect a specified range of signals from the knock sensor.

Most information from the knock sensor will be bumps in the road or closing the car door. However, when a vibration is large enough, the knock sensor signal will trigger the computer to alert the driver. This is a protective measure meant to prevent complete engine failure.

What are the symptoms related to a bad knock sensor?

When the knock sensor sends a warning signal to the vehicle's computer, the computer will usually reduce power output and illuminate the check engine light. Some vehicles will not restart until the problem has been fixed.

» MORE: How to tell if you have a bad knock sensor

Can I drive with a knock sensor problem?

No. When the knock sensor sends a warning to the computer, it is always treated as if there is an internal engine failure. The vehicle should not be started or driven until the knock sensor is diagnosed as faulty, or the issue is repaired.

How often do knock sensors need to be replaced?

On most vehicles, the knock sensor is tough enough to last over 150,000 miles.

Knock Sensor Replacement Cost Estimates

The average cost for a Knock Sensor Replacement is between $416 and $545 but can vary from car to car.