Weather or Bad O2 Sensor?

Fluxeon · 03-15-2017, 06:23 AM

Recently I have had misfires only on cold start ups. Never had this issues until we had a sudden temperature drop in the mornings for the past few days. By the time it heats up in the afternoon the car seems to be fine and I can usually just clear the codes. This morning however. I had multiple misfires and I shot a P2C78-Lambda probe after catalytic converter 2. I have not really been able to find anything on this code except for possible bad O2 sensor. Just wondering if anyone has had this problem or could help me. Spark plugs, coils, injectors all replaced roughly 2K miles ago.

Neiman Levenson · 03-15-2017, 09:12 AM

Hey man I had a similiar problem a month or so ago. Ultimately it was my pre-cat O2 sensors that went bad, and I knew because my gas mileage had dropped significantly. when I changed them out I saw they were completely burned up and the new 02 sensors made the car drive great again.

feuer · 03-15-2017, 09:44 AM

Pull a log once the car is at proper operating temp...we might be able to see if you have possible leaking injectors.

techwhiz · 03-15-2017, 09:53 AM

Anytime you get an O2 error. Stop investigating anything other than the O2 problem.

03-15-2017, 06:23 AM	#1
Fluxeon Registered 2 Rep 2 Posts Drives: 2007 335i E90 AT Join Date: May 2016 Location: USA iTrader: (0)	Weather or Bad O2 Sensor? Recently I have had misfires only on cold start ups. Never had this issues until we had a sudden temperature drop in the mornings for the past few days. By the time it heats up in the afternoon the car seems to be fine and I can usually just clear the codes. This morning however. I had multiple misfires and I shot a P2C78-Lambda probe after catalytic converter 2. I have not really been able to find anything on this code except for possible bad O2 sensor. Just wondering if anyone has had this problem or could help me. Spark plugs, coils, injectors all replaced roughly 2K miles ago. __________________ 07 335i AT, COBB STG 2 Tune, BMS DCI, VRSF 7" FMIC, VRSF CATLESS DPs, VRSF Exhaust, ER Chargepipe with HKS BOV.
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03-15-2017, 09:12 AM	#2
Neiman Levenson First Lieutenant 258 Rep 373 Posts Drives: 2008 135i M-sport Join Date: Mar 2017 Location: Richmond, Virginia iTrader: (0)	Hey man I had a similiar problem a month or so ago. Ultimately it was my pre-cat O2 sensors that went bad, and I knew because my gas mileage had dropped significantly. when I changed them out I saw they were completely burned up and the new 02 sensors made the car drive great again. __________________ 2010 LeMans Blue 6MT M-Sport \| Motiv 800 Single Turbo https://www.youtube.com/c/NeimanLevenson https://www.instagram.com/neiman_levenson/?hl=en
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03-15-2017, 09:44 AM	#3
FCobra94 Guest 0 Rep n/a Posts Drives:	Pull a log once the car is at proper operating temp...we might be able to see if you have possible leaking injectors.
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03-15-2017, 09:53 AM	#4
techwhiz Colonel 453 Rep 2,973 Posts Drives: e90 335i Sedan - Arctic Join Date: Feb 2012 Location: Bay Area, Ca iTrader: (4)	Anytime you get an O2 error. Stop investigating anything other than the O2 problem. __________________ Arctic Metallic\CF Splitters, Spoiler, Mirror Covers\LED Tails\LSD\Tinted\Coded\Apex Square SM10-19"\LED Angel Eyes\Gloss Black Grill\Integrated V1 & Galaxy Tab\M-Performance Brakes\Cobb Tuned\xHP Flash\Resonator Removed and -> is your friend.
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