07 E550 pre-cat O2 sensors issues
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Newbie
Joined: Mar 2017
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2007 E550
07 E550 pre-cat O2 sensors issues
Hello everybody, bought this car with the check engine light on, codes P-2237 and P-2240, O2 sensor heater circuit open, I replaced both sensors Bank-1 sensor-1 and bank-2 sensor-1, checked the harnesses, cranked it up and nothing changed. I have read many postings but don't know which fuse and or relay would control the input voltage to the sensors and or if the voltage goes straight from the ECM to the sensors? Please chime in with your helpful inputs! 
Last edited by mojoe550; Mar 27, 2017 at 04:11 PM.
Thread Starter
Newbie
Joined: Mar 2017
Posts: 6
Likes: 1
2007 E550
Wow, I didn't even get one reply, am I in the wrong forum or is my question inadequate? any ways I'm just trying to figure out where to start tracing the heater voltage for the O2 sensors. Any body have any suggestions please?...Thanks!
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