O2 sensor codes heater fault all four sensors

rowingone · 10-27-2015, 03:56 PM

If you get 4 codes for your O2 sensor heater circuit check your crankcase vent heater under the intake manifold. Mine was rotted so bad that when I touched it with a screwdriver the two wires just fell out. Part is about $90. I spent too much time trying to find a wire fault with the O2 sensor wires - if I had checked this first I would have seen the problem.

SpeedBuggy · 01-20-2016, 07:33 PM

Check Engine Light on, faults for all O2 sensors.

Dealership diagnosed the car and found sensors to be good. Further check found a blown fuse (Fuse #4 underhood engine electronics), replaced it and the fuse immediately blew again. All lines and connections were good and found a short circuit in the Crank Case Heater Valve. Replaced the valve, a gasket along with a clip and fuse, good to go now.

10-27-2015, 03:56 PM	#1
rowingone Second Lieutenant 5 Rep 212 Posts Drives: 2006 330 xi Join Date: Nov 2013 Location: colorado iTrader: (0)	O2 sensor codes heater fault all four sensors If you get 4 codes for your O2 sensor heater circuit check your crankcase vent heater under the intake manifold. Mine was rotted so bad that when I touched it with a screwdriver the two wires just fell out. Part is about $90. I spent too much time trying to find a wire fault with the O2 sensor wires - if I had checked this first I would have seen the problem.
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01-20-2016, 07:33 PM	#2
SpeedBuggy Comfortably Numb 627 Rep 654 Posts Drives: '18 x1/'13 X3/'06 330i Join Date: Mar 2009 Location: Cortland, Ohio iTrader: (0) Garage List 2006 BMW 330i [0.00]	Check Engine Light on, faults for all O2 sensors. Dealership diagnosed the car and found sensors to be good. Further check found a blown fuse (Fuse #4 underhood engine electronics), replaced it and the fuse immediately blew again. All lines and connections were good and found a short circuit in the Crank Case Heater Valve. Replaced the valve, a gasket along with a clip and fuse, good to go now. __________________ 06 e90 330i/Alpine White/Terra Dakota 13 F25 X3 xDrive 35i/Black Sapphire Metallic/Oyster Nevada 18 F48 X1 xDrive 28i/Black Sapphire Metallic/Black SensaTec
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