OBD2 knock sensors with OBD1

[ncbrock]

Every single pair of OBDI knock sensors I find in the junkyard are cracked and broken. I have two pair of nice OBD2 knock sensors and a spare harness and I'd like to find a way to make this work because new OBD1 sensors are expensive. I've searched some on here and bimmerforums and cant find much information, the info I did find wasn't really detailed enough or they didn't finish what they started.

Basically the OBD1 sensors have a green wire in the #1 position on the connector, and a black wire on the #2 position on the connector. The OBD2 sensor has a single 4 prong plug with a black and yellow going to each sensor. Could I just hookup yellows to greens and blacks to blacks?

[justin_l_]

http://www.bimmerforums.com/forum/showthread.php?1709090-How-do-I-splice-OBDII-knock-sensors-into-OBDI-harness&highlight=knock%20sensor

[ncbrock]

Yeah I saw that thread but he never finished it to confirm if any of his diagrams worked, if I mess it up then I'm SOL.

[DesertBMW]

They won't work. they work at different voltage. Got to have OBD1 knock sensors.

[ncbrock]

There are a couple of people on bimmerforums that say they are the same signal and work fine, but didn't really disclose any details. I pm'ed them on there hoping to get a response.

I did both knock sensors on my 95 M3 back in 2004, and I just had to do them again this past weekend. The OE Bosch sensors are poorly constructed, and the plastic that insulates the piezoelectric knock sensor head gets brittle very quickly from the heat its exposed to and it shrinks, cracking, and often times simply falling off.

Moisture intrusion then promptly destroys the sensor, and you start getting intermittent 1226 codes, and suffer from reduced low end torque as a result of retarded timing.

All that said this time I decided not to waste any money on the crap 95 back Bosch sensors and to install the all but bulletproof 95-99 sensor. The later style sensor as both sensors on one connector so cut the connector off and cut back both pigtails to the length of the old style sensors. Reuse the old connectors with a pin release tool and match the wires up black > black and yellow > green.

Solder the pins to the new sensors and snap them back into the connector housing. Install the new sensors and never have to worry about the POS Bosch ones falling apart again in a few years.


Also.. whenever I do this job for customers I always just pull the manifold. It adds less than 15 minutes to the process assuming you have the right tools and know what you are doing. It gives you opportunity to then replace a few orings, hoses, and intake manifold gaskets that are certainly on borrowed time if you are changing the knock sensors for the first time.

I think what he is saying is what I was thinking in the first place. Black to black and green to yellow.

[Habla]

They are $35 a piece on Amazon...