Two New knock sensors- 95 525i [Archive] - Bimmerfest - BMW Forums

: Two New knock sensors- 95 525i

10-12-2009, 03:58 PM
Had my indy install both new knock sensors. Had to remove the intake manifold. Made quite a difference, especially for in-town. Have been out on road yet.

Car seems much more eager, espec1ally below 2500 rpm. I had the rear 4-6 knock sensor go out and car felt sluggish and fuel economy dropped. Much better now.

Only issue was the small water activated thermostat that connects to the airbox crumbled. Apprently like all plastic items related ot the cooling system. Neve knew this part was even there.

More info: My Peake tool indicated a code 45 which indicated a problem "relating" to the knock sensors for cylinder's 4-6. Cleared it several times and it came back. My indy ran additional checks which indicated timing was retarded due to failure of the knock sensor. I do not know much more detail.

10-14-2009, 10:28 PM
after a couple of days driving seems like no real change in economy. Power and smoothness is much better.

10-16-2009, 11:32 AM
how did he know to change the knock sensors did the cel code show knock sensors.

10-16-2009, 12:45 PM
Sorry, I do not know the details. i know he ran various tests to rule out other causes. For example he did a smoke test to see if vacumn leaks. I do know the car is much stronger. It will spin the tires if i really try. it would never do that before. :) Gas mileage seems about the same.