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87 Posts
Discussion Starter · #1 ·
91 E34 525 M50
fault code 70 O2 sssensor circuit problem
replaced O2 twice in a 3 month period to rule out O2

i have a problem with my O2 the heater relay wont send the 12 v to the heater , but the relay is good the wiring to the O2 is good. the voltage and ground on the relay plug are good but the ecu wont close the realy . if you have dealt with this problem before please let me know.

thank you
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