HELP! E90 Acceleration Hesitation with High Aux Fan? (MAF/IAT Codes)

mmbingo · 12-12-2018, 12:32 AM

Car: 2011 328i xDrive SULEV (N51), Manual Trans (6 speed)

Issue: Last week I noticed when shifting from 4th to 5th and 5th to 6th my car would hesitate before accelerating. Even at WOT, I would receive no power for 2-3 seconds. This was weird but it only happened a couple of times. Then a couple days later (this past weekend), this hesitation happened in between every gear and has continued to happen. Also, when heel/toe'ing to downshift there is no response from the throttle.
Later that day, when I turned on my car the aux fan started running on high (outside temp is 25-35deg F) and would stay on continually while driving, in addition to the hesitation.

Doing some searching, the aux fan condition seems to be a sign of an impending water pump failure. Apparently there should be some codes thrown when this happens, before the check engine light comes on.

So I decided to do the sensible thing and buy a bluetooth scanner - so I bought a "Carista" and used the 1 month of free full features to get BMW-specific codes.

Yesterday: Codes for IAT Circuit High Input (P0113) and MAF Circuit Problem (P0100) appeared, but no water pump codes. So I ordered a new MAF/IAT sensor. Issues continue with hesitation and high aux fan.
Today: (The sensor has not arrived yet) I check for codes again but the IAT and MAF codes do not appear! Issues still continue with hesitation and high aux fan.

A few questions:
1. Is this Carista crap and should I return it and get a more reliable scanner?
2. This sounds like an MAF issue to me - what does the bimmerforum universe think? Would my check engine light appear if my MAF failed (because it has not)?
3. If my MAF/IAT failed, could it lead to my aux fan running on high, or are these separate issues?

Thanks!!

hassmaschine · 12-12-2018, 12:36 AM

Generic code readers only show codes mandated by OBDII emissions laws - which doesn't cover the water pump and lots of other things.

mmbingo · 12-12-2018, 02:29 PM

Quote:

Originally Posted by hassmaschine

Generic code readers only show codes mandated by OBDII emissions laws - which doesn't cover the water pump and lots of other things.

With Carista you pay for the manufacturer specific diagnostics.

12-12-2018, 12:32 AM	#1
mmbingo New Member 0 Rep 8 Posts Drives: 2011 328xi Join Date: Aug 2016 Location: Detroit, MI iTrader: (0)	HELP! E90 Acceleration Hesitation with High Aux Fan? (MAF/IAT Codes) Car: 2011 328i xDrive SULEV (N51), Manual Trans (6 speed) Issue: Last week I noticed when shifting from 4th to 5th and 5th to 6th my car would hesitate before accelerating. Even at WOT, I would receive no power for 2-3 seconds. This was weird but it only happened a couple of times. Then a couple days later (this past weekend), this hesitation happened in between every gear and has continued to happen. Also, when heel/toe'ing to downshift there is no response from the throttle. Later that day, when I turned on my car the aux fan started running on high (outside temp is 25-35deg F) and would stay on continually while driving, in addition to the hesitation. Doing some searching, the aux fan condition seems to be a sign of an impending water pump failure. Apparently there should be some codes thrown when this happens, before the check engine light comes on. So I decided to do the sensible thing and buy a bluetooth scanner - so I bought a "Carista" and used the 1 month of free full features to get BMW-specific codes. Yesterday: Codes for IAT Circuit High Input (P0113) and MAF Circuit Problem (P0100) appeared, but no water pump codes. So I ordered a new MAF/IAT sensor. Issues continue with hesitation and high aux fan. Today: (The sensor has not arrived yet) I check for codes again but the IAT and MAF codes do not appear! Issues still continue with hesitation and high aux fan. A few questions: 1. Is this Carista crap and should I return it and get a more reliable scanner? 2. This sounds like an MAF issue to me - what does the bimmerforum universe think? Would my check engine light appear if my MAF failed (because it has not)? 3. If my MAF/IAT failed, could it lead to my aux fan running on high, or are these separate issues? Thanks!!
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12-12-2018, 12:36 AM	#2
hassmaschine Major General 3966 Rep 7,215 Posts Drives: "NBO" 330i Join Date: Jun 2014 Location: earth iTrader: (0)	Generic code readers only show codes mandated by OBDII emissions laws - which doesn't cover the water pump and lots of other things.
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