Knock Sensor...

[sy5alive]

Got a check engine light a few days ago. Turned out to be Knock Control
Test Sensor and Knock Sensor #2. I put in new gas and cleared the codes.
They have not reappeared since.

Should I be worried at all about this? Will this come and bite me in the ass? If so, what precautionary measures should I take to avoid any future problems related to this?

Thanks,

Tommy
'94 318is

[bitcore]

It could have just been a bad tank of gas of low octane to cause the knock sensor to throw a code, or the sensor could have malfunctioned and the computer threw a code.

I'm really not sure, you'll have to get an answer from someone here who has much greater knowedge of what those codes COULD mean. Was the engine acting funny when the codes were thrown? making any funky noises, shaking, etc?

[sy5alive]

Nope, no rattles or shakes. Only codes it threw were the two knock sensor-related ones.

[91notchback]

Originally posted by sy5alive@Nov 26 2004, 01:00 PM
Nope, no rattles or shakes. Only codes it threw were the two knock sensor-related ones.

[snapback]237873[/snapback]

if you get this again i would recommend putting 93 octaine in and bringing it to a dealership, not shure what type of pistons they use, but if they are Hypereutectic pistons they will crack with very little detination. even if the arnt its still very bad for the motor

[bitcore]

yes. Be sorta weary until it happens again. If it dosn't happen again withen a month, just keep putting the recomended octane or higher in and keep doing that. Don't buy anything less than mid-grade [I forget the number]
BMW engines run at a high compression so they need a higher octane so they don't knock. It dosn't mean you need premium, you just need what's listed on the gas cap flap thingy.

[sy5alive]

thanks dudes

[DesmoBob]

if the problem keeps coming back after driving a month with the higher octane, the sensor may be bad.

common sensor problem is they crack. replacement of the sensor itself isn't hard, the most PITA part is removing the intake manifold, although i am unfamiliar with m42/m40, so i don't know if that's necessary in your case.

[dagoo98]

Originally posted by sy5alive@Nov 26 2004, 01:58 AM
Got a check engine light a few days ago. Turned out to be Knock Control
Test Sensor and Knock Sensor #2. I put in new gas and cleared the codes.
They have not reappeared since.

Should I be worried at all about this? Will this come and bite me in the ass? If so, what precautionary measures should I take to avoid any future problems related to this?

Thanks,

Tommy
'94 318is

[snapback]237623[/snapback]

Cheap gas is the common cause of this problem. My uncle also used to use cheap gas until he saw the check engine light come on as a result of his frugal spending. Hope that you learn from this also. If you use cheap gas in these cars to try and save money you will end up paying more in the long run on engine repairs.