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A knock sensor assures that you're getting as much power and fuel economy as is possible from your engine.

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A knock sensor allows the engine to run with the ignition timing as far advanced as possible. The computer will continue to advance the timing until the knock sensor detects pinging. At that point the computer retards the ignition timing just enough for the pinging to stop.

The knock sensor responds to spark knock caused by Pre-detonation of the Air/Fuel mixture. As the flame front moves out from the spark plug ignition point, pressure waves in the chamber crash into the piston or cylinder walls resulting in a sound known as a knock or ping. This is caused by using a fuel with a low octane rating, overheating, or over advanced timing. Sometimes it can be caused by hot carbon deposits on the piston or cylinder head that raise compression. A knock sensor is comprised of Piezoelectric materials; Crystals that when impacted, generate a voltage (same idea as a BBQ ignitor). This voltage is monitored by the computer, and when an irregularity is detected, the computer corrects timing in VVT (variable valve timing) engines, or triggers a DTC Diagnostic Trouble Code) in older vehicles.

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βˆ™ 10y ago
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βˆ™ 3y ago
I had a knocking sound in my 2004 SSR and had a mechanic tell me it was a common issue with the engine type. Β At that time gas was upwards of $4 a gallon I was using regular. Fuel prices are down and I switched to a high octane. Β Problem solved!
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βˆ™ 14y ago

No. Worst case senario with a bad knock sensor is check engine light, and bad fuel economy. Also spark knock, which if not taken care of can cause excessive heat to build in the engine and cause premature failure.

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βˆ™ 9y ago

In most cases corrosion will cause a knock sensor to go bad. The knock sensor can also be shorted out by an electrical surge.

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βˆ™ 10y ago

It will cause it to run sluggishly.

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βˆ™ 14y ago

It could.

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Q: Can a bad knock sensor cause the car do start bad?
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Can a defective knock sensor cause bad mileage?


What can happen if a knock sensor is bad?

the motor could pre-detonate or "knock" that can cause damage

Could a bad knock sensor cause your car not to start?

No all it is is basically a microphone to monitor for noise-nothing to do with the engine running.

Will a bad knock sensor stop a Volvo 240 from starting?

I have a 240 and with the knock sensor unplugged it will still start so I would have to say no.

Will a knock sensor start working correctly if you start using a high octane fuel?

Perhaps--unless the sensor itself is bad.

What happens if you drive the vehicle with a bad knock sensor?

If you run your rig with a bad knock sensor the computer will not be able to tell if or when your engine starts to knock (such as a rod knocking). That is if it isn't already cause the sensor is there for insurance. Make sure the sensor is bad and if so have it replaced asap. It is an expensive job cause you have to remove the intake to get to them (some engines have two under the intake). willyray3

Can a bad crankshaft sensor cause a2.3ford not to crank?

A bad crankshaft sensor on a 2.3 Ford may cause the car to not start. A bad crankshaft sensor can crank, just not start.

Can a bad knock sensor cause your car to shutoff?

yes, it is protecting the motor from damage.

What does a car do when the knock sensor is bad?

The knock sensor retards the engine timing when there is a knock or ping detected. This will make the car a little sluggish. It is rare that the knock sensor goes bad.

Will it hurt engine to drive with bad knock sensor?

Yes it can hurt your engine to drive with a bad knock sensor. The knock sensor should be replaced as soon as possible.

Will a bad heat sensor cause your Chevy s10 blazer not to start?

A bad engine temp sensor can do that.

Can a knock sensor correct itself?

If the sensor it'self is bad then NO.