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BMW 3-Series (E90 E92) Forum
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O2 Heater circuit trouble
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02-08-2024, 02:57 PM | #1 |
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O2 Heater circuit trouble
Hey guys. I have a 2011 335xi N55. I recently replaced my upstream O2 sensor due to a P0030 (2D0D), and while I got the new sensor in and the car runs better than it ever has... I still have the code. All of the diagrams I reference say it's fuse #38 as a 30A fuse, but in that spot I found a 15A fuse. Then I searched the DME box in the upper passenger side of the engine bay and didn't find the 5 fuse box I see in other videos. I can't find a fuse to pin the DTC on and I also can't identify which wires are for the heater circuit. ProDemand is being useless and I'm a Subaru tech so I have limited access to the correct diagrams. Can someone clarify whether or not there even is a fuse and/or which wires are for the heater control circuit so I can check continuity across said circuit on this new sensor??
I'm just trying to take care of the dash lights. I also have a 93B2 for the BST that I can't figure out since putting in a new BST, and a TPMS light because I had to take out the TPMS module due to a broken pin stuck in the connector/shorting out the CIC/combimeter screens. Making this car mint is going to kill me, but any help is greatly appreciated |
02-08-2024, 06:44 PM | #2 | |
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Working Backwards on Your Points Raised: 1) 93B2 Code is in the MRS Module, and indicates that your "Trigger" wires from the MRS to the Battery Safety Terminal (G19a) are OPEN-circuit, so that the MRS could NOT "Blow" the BST pyrotechnics to prevent battery voltage from going to the Alternator/ Starter in frontal collision. If someone who didn't take the time to understand the BST circuit changed/ disconnected the Battery, it may have resulted in one of the two "Trigger" wires (Black & Yellow) being loose, damaged or disconnected. See ISTA ScreenPrints attached to NEXT POST. If that Trigger Circuit is "Open", then it would be expected that Airbag & Seatbelt warning lights are illuminated. Here is Definition: 93B2 | MRS: Safety battery terminal | mrs7 | Multiple restraint system 2) 2D0D: Definition & Link to Fault Info Sheet: See Description, & Service Plan: P0030 | 2D0D | Oxygen sensor heating before catalytic converter, activation: Line disconnection | MEVD176K https://bmwfault.codes/XMLDiagView?d...MANQA2ADAANAA= The ISTA 'Lambda Control' wiring diagram (SSP), Component Location & Connector View ScreenPrints are attached to NEXT Post. Also attached there are ScreenPrints of Bentley Fuse Chart for 2008 & Later E9x models (2 pages). I would inspect & electrically TEST for Line faults (loose/ damaged wire or connector) in the BSD Lines near battery & O2 Sensor Connector X62001, testing BOTH for Battery voltage at X62001/4, Red/Green Wire, Ignition ON, and also for continuity between X62001/3 and DME Connector X60002/17 (White/Blue wire). BTW, E9x models built BEFORE 3/1/2007 had the 5-fuse carrier in E-box under hood. Your F38 fuse is on JB Fuse panel INSIDE vehicle, beneath Glovebox. If you need any other info and can't find Free ISTA Download, please let me know what you need. George |
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02-08-2024, 09:42 PM | #4 | |
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Regarding #2 - I will try to test these connectors but F38 in the glove compartment in my car is a 15A fuse. Should it be a 30A like it states in the above pictures? ProDemand states F38 is 30A/15A so I'm unsure if this just doesn't have the correct fuse in it or not. Last edited by BSM-MSPORT; 02-08-2024 at 09:52 PM.. |
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02-08-2024, 11:16 PM | #5 | |
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I would suggest measuring Resistance/ Ohms across BST pins/sockets, and then with Yellow & Black wires inserted in BST, stick pins in those two wires and measure resistance across two pins. If NO significant increase in resistance in 2nd test, test for damage which increases resistance elsewhere in those two wires, going to the MRS. F38: I would suggest pulling 15A fuse in F38 slot on JB Fuse Panel, examining the fuse to see if it is blown, & testing it electrically as well for ~ 0 Ohms resistance between spades. Test for battery voltage in reference to chassis ground, in each of two F38 sockets with fuse still removed. If NO or ~ 0 Volts, you have a K6300 DME Main Relay activation issue, or wiring issue between relay & fuse socket. K6300 relay is soldered to JB Circuit Board, as opposed to removable. It seldom fails, but if no voltage at F38 sockets with Ignition on, also test for voltage (Ignition ON) at sockets of F11, F16 & F37. If there WAS voltage at F38 Socket, OR if F38 was "blown", insert 30A fuse in F38 socket and see if car starts, or if F38 blows again. If 30A fuse in F38 socket blows, remove fuse & measure Ohms resistance between "Downstream" fuse socket, (Right-hand socket(?), or socket that did NOT have Battery voltage with ignition ON), and Chassis Ground (Ignition OFF). Please let us know what you find, George |
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