[Bobocut95]

Hello all,

I'm in a bit of a doosie here with my bmw 328xi 2007 196k miles. My engine seems to be knocking/missfiring/hesitating a lot at 50mph plus. Along with that I had codes 2Ca6 and 2CA7 appear at the same time when reving to a high rpm on the highway which resulted in an engine shutdown. I also had an instance where the car speeds would not go over 65mph gas milage was horrible and the car was rattling underneath. Now my car idles rough with the rpms fluctuating constantly from time to time and a little rough on startup idle.

As a side note My downstream o2 sensors where found burnt up at the covers a year ago which were replaced and my mechanic told me my catalytic converters were starting to go. Not sure if now is the time to replace it or go for the 02 sensors before the catalytic converter.



Here is the story

Initially it would missfire on the highway above speeds of 50mph the check engine light and bmw yellow service light would flash and go away. It gets worse at higher speeds. I tried to get a code read by Auto zone but nothing was there. I tried to duplicate the fault by revving higher on the highway and Finally the engine died and I pulled over to restart it. This time with the check engine light steady on. One euroshop before getting the steady check engine light said it was my plugs which I only had 25k miles on( bostch ). This didn't help when replaced.Maf also replaced. They said my catalytic converters were fine.

Who do I trust ? Should I take the car to a exhaust shop and replace the converters or replace the 02 sensors. It's been about 50k miles since I got my exhaust manifolds smogged out.

[gbalthrop]

Those two codes, "26AC" & "26A7" are NOT found in (1) Bentley, (2) BMW Fault Code Lookup, or (3) Google.

1) What Scan Tool or Software are you/whoever using to read those codes? and
2) WHAT does that device/software provide as a code definition, and module in which saved?
3) What Scan Tool do you have available (Brand & Model)?

George

[Bobocut95]

Apologies I converted those codes online. P166F and P165F were the raw ones taken at AutoZone. Couldn't find anything on them.

[gbalthrop]

Originally Posted by Bobocut95

Apologies I converted those codes online. P166F and P165F were the raw ones taken at AutoZone. Couldn't find anything on them.

Fault Code Definitions per Bentley:

P165F | 2CA6 | Internal Control Module Measurement Error 02 Sensor Heating (Bank 1 Sensor 1)

P166F 2CA7 Internal Control Module Measurement Error 02 Sensor Heating (Bank 2 Sensor 1)

P166F 2CAB Internal Control Module Measurement Error 02 Sensor Heating (Bank 2 Sensor 1)

So you see that regardless of whether P-codes or BMW FC's are read, the result is the same: BOTH your Pre-cat O2 Sensor heaters are NOT functioning, or the DME's ability to measure heater activation is NOT functioning. It you were to use INPA or some BMW-specific software to read those Fault Codes, their DEFINITIONS and DETAILS, you would probably find that "Error 02" means value received (voltage) by DME is TOO LOW or "below threshold" which suggests either the sensor heater Voltage Supply is disconnected OR the Fuse that powers it has blown/ Have you had the Breather Heater Recall performed on your vehicle?

Here is the Breather Heater & O2 Sensor Heater circuit and FUSE CIRCUIT for Early 2007, & Late 2007 (build date >3/1/2007) 328xi; NOTE: all 5 heaters are on SAME FUSE, and recall is for replacement of original Breather Heater which can short out:
-2007/02:
https://www.newtis.info/tisv2/a/en/e...ontrol/otwHfc8
https://www.newtis.info/tisv2/a/en/e...xi-lim/uM1qAq9

2007/03 - 2007/08:
https://www.newtis.info/tisv2/a/en/e...ontrol/x5UZsdI
https://www.newtis.info/tisv2/a/en/e...xi-lim/vEO0UYq

So that's F04 in the E-box for early 2007 & 2006 models, and F79 in the JB Fuse Panel for late 2007 models. It's fuse F38 for 2008 & LATER models.

You stated: "My downstream o2 sensors where found burnt up at the covers a year ago which were replaced and my mechanic told me my catalytic converters were starting to go." Did your mechanic tell you about the "Breather Heater Recall" and the fact that the O2 sensors are on the SAME circuit? If he did NOT know those things, he probably did NOT test for heater function or check the appropriate Fuse.

I'm NOT sure what you are describing when you say "burnt up at the covers" but that suggests to me that there was a wiring fault or short-circuit which caused heat damage and possible "melting" of the O2 sensor connector & perhaps wiring. It would be helpful to know WHICH Sensors were involved. If you mean Post-cat sensors only (downstream of the Catalytic Converters on each bank), that may be significant to diagnosis of other issues. When did your performance symptoms begin in relation to THAT "burning" of the O2 sensors?

I'm NOT sure that lack of O2 Sensor Heater function would cause all the symptoms you describe, BUT I would suggest address the O2 Sensor Heater Circuit issues (the problem is NOT the O2 sensors themselves, so do NOT throw parts at it), and see what your symptoms or other codes are AFTER Heater function is restored. You may have damage to other wiring as a result of the incident "a year ago", so just address ONE thing at a time.

As first steps which YOU can do, I would suggest the following:
1) check your build month/year per driver door jamb label;
2) check appropriate fuse (F04 or F79);
3) Let us know results of those, AND if you have/can get a cheap multimeter to do basic electrical testing (with specific procedures provided by forum):
https://www.harborfreight.com/7-func...ter-63759.html
4) You might also consider getting a simple P-code reader that can give you MOST of the Fault Code information a more expensive or difficult to use BMW-specific tool can provide (most everything related to the engine except Electric Coolant Pump Codes). Here is a $35 example of such a tool, which can read and clear engine P-codes on any car sold in US since 1996:
https://www.amazon.com/Autel-AutoLin...NsaWNrPXRydWU=

I'm NOT pushing Autel, I simply list that as ONE of MANY similar products, and it happens to be one I have used. I also have & use INPA which is BMW Factory "Engineers" Software. INPA takes hours to learn to use and is mostly in German. ANYONE who can read & find the OBD II Socket can use the Autel to Read & Clear Codes in an hour or less.

I strongly suggest "walking BEFORE running." You can always move up to more capable Scan Tools or Software that can connect to, and read Fault Codes & Live Data (Parameters) in, ANY of ~ 20 Modules in your vehicle, including Transmission, Transfer Case, DSC/DXC or ABS, CAS, etc. BTW, if you have a Windows 10 Laptop, you might prefer this basic P-code reading software which allows you to save Data readouts on your computer ($30 --which I also have ;-):
https://www.amazon.com/ScanTool-OBDL...gateway&sr=8-1

Please let us know what you find,
George

[Bobocut95]

Thank You I will get back to you on everything.


I keep a excel history of all maintenance performed at what mileage's and dates, and feedback from the maintenance teams. Funnily enough the blower motor recall was done two weeks ago. I put 75 k miles on this car in two years All high way miles. The O2 sensors I mentioned that were replaced were post cat. It's weird because I had to have my crankshaft position sensor and both camshaft position sensors replaced three weeks ago. Too many sensors at once to fix other vehicle issues


Give me a few days... Thanks George!

[Bobocut95]

Issue turned out be the two camshaft sprockets underneath the valve cover. Apparently there was a service bulletin to replace them with upgraded ones. Too costly for repair.