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Discussion Starter · #1 ·
I posted earlier about my rear 02 not working .. I put in new sensor .. Blah Blah..

I pinged out the wires fron the DME to the sensor and none were broke .. shook the harness and no shorts.

This pretty much says the DME is NG ..

Question , I plan to get a used DME from Ebay .. will I need to bypass the EWS when I get it ?? I looked for a EWS bypass DIY for the 318 but found only bypass instructions for older models .

The other choice I have is to put the old DME in .. Drive to BMW garage and let them "re synch" the new DME ..

Which option is best ?

Thanks
 

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You need to go to the stickies and find the link to download the Bentley manual. If you look at the wiring diagram for the 1.9L engine it shows the voltage for the O2 heat comes from the engine control module relay to the O2 sensor. The DME grounds the other side of the heater to turn it on and off. The wire leaving the ECM relay is red/white but it gets spliced to a green wire to go to the O2 sensor. You need to check from the green wire to the chassis of the car to see if you have 12V at the O2 sensor or not. I don't think you have a DME problem.
 

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Discussion Starter · #3 ·
Thanks for the reply .. I have the manual .. the 1.9 does not have the relay .. voltage direct from DME

What I did finally was resolder all the pins that hold on the connector on the DME board .. I am with you , I think the DME is fine , I couldn't see any signs of damage or heat . I figured maybe some of the solder joints loosened .. all is "better" now . I am getting a signal from the sensor which I was not before , but i did not verify the 12 volts to heat the unit . My scan tool shows the sensor working , but it seems to take awhile .. I will run for a while and see if I get any error codes . I got a P0420 code 60 miles after I put in the DME . But I think that could have been from the past owner driving around with the light on so long .. Lots of stuff in the converter .

Thanks again
 

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If you're looking at page ELE-82 of the Bentley there is a connection from the DME to the heater of the O2 sensor but that's the low side. Follow the grn wire at the other side of the heater element and it connects to the +12V buss which is red/white and shown as a dashed line. Power is applied to this bus when the ECM relay (upper right on the page) closes and applies +12V. The DME controls the O2 sensor heat by grounding the low side.
 

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Discussion Starter · #5 ·
I would think this relay is fine since the forward 02 sensor works well .. if the module was NG then lots of things would not be functioning .,, or am I missing something ?

Thanks
 
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