Service light on - found out service code on 2007 BMW 328xi

I just used the service code reader at an auto store and found out that my service light is on due to code P135B. Is anyone familiar with what that code means? Thanks

by in Herndon, VA on April 17, 2011
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1 answer 2 comments
ANSWER by , April 18, 2011
code P135B is knock sensor signal 2 plausibility
COMMENT by , April 18, 2011
I am not sure I know what that means but thank you very much for taking time to reply to me. I can probably look that up on-line as well...
COMMENT by , December 17, 2013
I never heard of a knock sensor; but usually knock refers to when a lower grade gasoline is put into a vehicle than that which it is designed to run on; and as a result the fuel detonates (spark plug fires) before it is supposed to which results in a knocking sound. You can hear a car knocking when this happens; but the the 2007 328xi BMW's are designed to run on a minimum octane of 87 (regular grade gas), 89 (mid grade gas) or 91 (hi test gas, which is designed to run on). I think you get less performance if you put octane 87 or 89 in the vehicle but it should run fine.