Is it Safe to Drive With a Faulty Knock Sensor?

A car knock sensor is located on the intake manifold, cylinder, or engine block. The purpose of the knock sensor is to sense unusual pulsations caused by the engine detonation. It is basically the computer’s ear to the engine to determine if it is working properly.

To get a better understanding of how a faulty knock sensor reacts, note the points below:

  • One symptom of a bad knock sensor is the engine doesn’t feel right while driving at speed, or while the vehicle is carrying a light or heavy load. If you notice something seems off with your vehicle, even if no light illuminates, it is best to have your car checked out by a mechanic.

  • A bad knock sensor may also not let the engine accelerate properly while driving on the highway, and cause the vehicle to lose fuel mileage. If you notice these things happening, you should have a certified mechanic from YourMechanic inspect why the car is slow to accelerate.

  • The computer in the vehicle’s control system can detect the different sounds in the car’s engine. If the computer doesn’t recognize a sound, it will illuminate the Check Engine Light. This is true for the knock sensor as well. If the knock sensor detects an abnormality, the computer will let you know with the Check Engine Light. If the Check Engine Light turns on, have a certified mechanic inspect your vehicle as soon as possible.

  • Once the computer realizes the knock sensor is not working properly, your vehicle will most likely lose power. How much power you will lose depends on the octane limit of the engine, and how heavily it relies on the knock sensor input. The vehicles that will lose the most power are high-compression and flex-fuel engines. This is because the loss of power will slow the timing and keep the transmission out of drive until the sensor has been replaced. The slow timing is designed to allow you to get to safety or get the vehicle fixed, but not allow you to go very far.

The knock sensor senses the vibrations of the engine and will decrease acceleration until the sensor is replaced. With a faulty sensor, there is a chance that higher emissions are being produced from the engine because the engine may run hot. The Environmental Protection Agency does not allow such high emissions from a vehicle, which is why the decreased acceleration safety feature is put in place.


The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

Symptoms of a Bad or Failing Barometric Sensor
Common signs include poor engine performance, like sluggish acceleration, lack of power, and misfires, as well as the Check Engine Light turning on.
How to Replace a Camshaft Position Sensor
Camshaft position sensors determine the position of the camshaft in relation to the crankshaft to control the fuel injector.
Can Sensors Be Cleaned or Do They Need to Be Replaced?
In In most cases, sensors for your automobile will need to be replaced if they fail, but depending on the type of sensor and its location or function, some can be cleaned and reused. Sensors can come in many...

Related questions

Car turns over, but will not start

Hello there, thank you for asking about your 1995 Chrysler Intrepid. The powertrain control module (PCM) controls ignition timing by controlling the ground path to each coil. It uses signals from the crank sensor and cam sensor to determine spark...

Engine shutting down.

Thank you for your inquiry. There are different options to take into consideration with diagnosing this issue. A restriction in the fuel delivery system is a likely cause. The fuel builds too slowly, enough to start the vehicle, but not...

The speedometer, odometer, & mileage gauges are not working.

This is likely related to what is called a speed input/output shaft sensor which is a sensor mounted down on the transmission that monitors the speed of the output shaft of the transmission. This is relayed to your ECU which...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com