Skip the auto shop - Our mechanics make house calls

Is it Safe to Drive With a Faulty Knock Sensor?

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
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

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

More related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2159 OBD-II Trouble Code: Vehicle Speed Sensor B Range/Performance
Diagnostic Trouble Code (DTC): P2159 P2159 code definition Vehicle Speed Sensor B Range/Performance Related Trouble Codes: P2158: Vehicle Speed Sensor B P2160: Vehicle Speed Sensor B Circuit Low P2161:...


Related questions

Q: knocking sound

You would first need to determine if the engine noise is a lower engine noise or an upper engine noise, as this would make a big difference on the repairs that would be needed for your 2000 Chrysler Town &...

Q: I need to find out the location of the Exhaust Camshaft Position Sensor Bank 1 on a 2008 Infiniti EX35.

Hello, thank you for writing in. The bank 1 camshaft position sensor is going to be located on the front of the engine. Most specifically it is going to be located right below the valve cover on the bank (or...

Q: Engine won't run - 2012 Buick Lacrosse

Hi there. Having to use a breaker bar, to free the engine from being locked-up, does not sound promising. Removing the serpentine belt, would eliminate an accessory component (ie; seized alternator) that may be preventing the engine from turning over....