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BMW and MINI Fault Codes – How to Determine Bank, Sensor and Cylinder Locations

January 12, 2018

Bank, Sensor, Cylinder …. How do I Know?

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When servicing or diagnosing faults with our BMWs and MINIs we will often be guided to a specific cylinder, bank or sensor location.  These location codes can be confusing, even if you basically know what they mean.  For example, Bank-2 cam refer to a group of cylinders … or … a specific sensor.  It depends on what type of engine the codes are being applied to.  So, how do we know which reference in being made?  Knowing how the reference system and coding works, for different engines, is key to understanding what the coding you are looking at means.

The most confusing term is “bank”.  No, this is not a reference to the institution where your bills are paid from.  On our internal combustion engines, bank can be referencing either a group of cylinders or the intake or exhaust “sides”, or camshafts, of the engine. Note in the details, below, how the use of “bank” can change depending on the engine being referenced.

Sensor 1 or 2 typically refers to some type of sensor that is applicable to the cylinder heads (such as camshaft position sensors), or the oxygen sensors.  If referencing cylinder head sensors, intake is #1 and exhaust is #2.  If referencing oxygen sensors, pre-cat is #1 and post-cat is #2.

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How To decipher Bank, Sensor, Cylinder and Firing Order on BMW Engines

In-line 4-cylinder (US models):

M10 – Single cam, produced through 1985 (US)
S14 – Twin cam, produced for 87 through 91 M3 (US)
M42 & M44 – Twin cam,  produced 1990 through 1998 (US)
N20 & N26 – Twin cam, turbocharged, produced 2012 to current date of this post (US)

* Cylinder numbering is from front to rear; 1 at the front and 4 at the rear.
* Ignition firing order is 1-3-4-2.
* These engines have only one bank (bank-1).  All cylinders (1 through 4) are considered bank-1.
* The intake side of the engine is #1 (as in “sensor-1″) and the exhaust side is #2.
NOTE:  Some codes will use “bank” to represent the intake and exhaust sides of the engine, since there are not multiple cylinder banks.  Example; Camshaft sensor, Bank-1 would mean the intake cam sensor.  A different reader may say; Camshaft sensor, Bank-1, sensor-1.  This is where we need to be aware of what engine we are looking at and how the code is represented.

In-line 6-cylinder (US models):

M20 – Single cam, belt driven camshaft, produced through 1991 (US)
M30 – Single cam, chain driven camshaft, produced through 1993 (US)
M88, S38 – Twin Cam, produced for M5 & M6 through 93 (US)
M50, M52, M54, M56, S50, S52, S54 – Twin cam,  produced 1991 through mid-2000s (US)
N51, N52 – Twin cam, produced from mid 2000s through 2011 US)
N54, N55, S55
– Twin cam, turbocharged, produced from mid 2000s to current date of this post (US)
B58 – Twin Cam,  turbocharged, produced from 2017 to current date of this post (US)

* Cylinder numbering is from front to rear; 1 at the front and 6 at the rear.
* Ignition firing order is 1-5-3-6-2-4.
* Engines produced through 1995, are generally considered as having one bank (bank-1).  All cylinders are bank-1.
* Engines produced from 1996-on are considered to have two banks (bank-1 and bank-2).  Cylinders 1 through 3 are bank-1 and cylinders 4 through 6 are bank-2.
* The intake side of the engine is #1 (as in “sensor-1″) and the exhaust side is #2
NOTE:  On pre-OBD-II engines (pre-1996), some codes will use “bank” to represent the intake and exhaust sides of the engine, since there are not multiple cylinder banks.  Example; Camshaft sensor, Bank-1 would mean the intake cam sensor.  A different reader may say; Camshaft sensor, Bank-1, sensor-1.  This is where we need to be aware of what engine we are looking at and how the code is represented.

8-cylinder, V8 (US models):

M60, M62, S62 – Twin cam, 4 valves per cylinder, produced from 1993 through mid-2000s (US)
N62, N63 – Twin cam, 4 valves per cylinder, produced from early 2000s to current date of this post (US)
S63 -
Twin cam, turbocharged, 4 valves per cylinder, produced from early 2000s to current date of this post (US)
S65
 – Twin cam, 4 valves per cylinder, produced from 2008 through 2013 (US)

* Cylinder numbering is 1 through 4 on passenger (right) side and 5 through 8 on driver (left) side.  numbers 1 and 5 are at the front, 4 and 8 are at the rear.
* Ignition firing order is 1-5-4-8-6-3-7-2 (except S65 = 1-5-4-8-7-2-6-3).
* Bank-1 is the passenger side (cylinders 1 through 4), bank-2 is the driver side (cylinders 5 through 8).
* The intake side of the engine is #1 (as in “sensor-1″) and the exhaust side is #2

10-cylinder, V10 (US models):

S85 – Twin cam, 4 valves per cylinder,  produced from 2005 through 2010 (US)

* Cylinder numbering is 1 through 5 on passenger (right) side and 6 through 10 on driver (left) side.  numbers 1 and 6 are at the front, 5 and 10 are at the rear.
* Ignition firing order is 1-6-5-10-2-7-3-8-4-9
* Bank-1 is the passenger side (cylinders 1 through 5), bank-2 is the driver side (cylinders 6 through 10).
* The intake side of the engine is #1 (as in “sensor-1″) and the exhaust side is #2

12-cylinder, V12 (US models):

M70, M73, S70 – Single cam, produced through early 2000s (US)
N73 – Twin cam, produced from early 2000s through 2016 (US)
N74 – Twin cam, turbocharged,  produced from 2008 through 2015 (US)

* Cylinder numbering is 1 through 6 on passenger (right) side and 7 through 12 on driver (left) side.  numbers 1 and 7 are at the front, 6 and 12 are at the rear.
* Ignition firing order is 1-7-5-11-3-9-6-12-2-8-4-10.
* Bank-1 is the passenger side (cylinders 1 through 6), bank-2 is the driver side (cylinders 7 through 12).
* The intake side of the engine is #1 (as in “sensor-1″) and the exhaust side is #2


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