On-Board Diagnostics Pt. 2

Posted by murmini Mon, 12 Mar 2007 15:54:00 GMT

While the primary measurements taken from the OBD are focussed on emissions, the OBD interface is capable of delivering a number of statistics and measurements about your vehicle and how it is performing.

It is routinely used by your dealer or service shop to locate and provide error codes from your vehicle. These can be referenced in tables that identify, with some specificity, exactly what is wrong.

There are two basic types of OBD measurement, static, such as those taken in a service shop and dynamic, which are measurements taken while the vehicle is in operation. Hooking your MINI up to vehicle-specific analyzers provides your technician with a very clear view of every piece of data being exchanged and distributed by your various bus systems. It reports on many aspects beyond just the engine, including all of the subsidiary items in the vehicle, such as those managed by the General Body Module.

In this day and age, its very difficult to conduct maintenance and repairs to the drivetrain or electronics without the aid of some minimal diagnostic device. Obviously, your MINI dealer has the OEM diagnostic, scan and software configuration tools such as the DISplus, GT1 or MoDiC. In most instances, automobile manufacturers will only sell these to authorized dealers, however, you can get very similar results from some third-party manufacturers such as PassThrough+ SX who manufacture and sell automotive analytic hard and software. These might cost you anything from $1,500 to $5,000 depending upon the level of their sophistication. You will also need the MINI / BMW adaptor cable and a subscription with the BMWTIS service and that runs from $25/day to several hundred dollars per year. That is available at BMW Technical Info but I warn you, you have to have Internet Explorer or Netscape to access it! (Ugh!).

There are, however, some excellent alternatives for obtaining more rudimentary data from your car including viewing and clearing fault codes and generally looking into the well-being of your vehicle. At the lowest end of the scale, you can obtain an OBD II code reader from most auto stores for well under $100. One of these will allow you to both read and reset Diagnostic Trouble Codes (DTCs).

These devices can be plugged into your OBD II port under the dash on the drivers side (US) and will provide you with a numeric code that you can look up either on-line on in a provided book. Several have the ability to be updated as vehicles are updated. More expensive ones add more features and provide ways to monitor the systems dynamically – while the vehicle is being driven.

More sophisticated still, are software packages that you can purchase that allow you to bring the power of a portable computer in to play. With the appropriate cable and the software installed on your laptop or handheld, you can start to approach the sophistication found in the much more expensive repair shop products. Following are two very different approaches to analysis, one more complex and the other very simple and very affordable:


Auto Enginuity is one such company that manufactures scan tool software that you can run on your PC, Pocket PC and Palm Pilot. It allows you to read your vehicle’s diagnostic trouble codes, live vehicle sensors (including wide-band O2 sensors), as well as inspection and maintenance system test results, in order to determine what service the vehicle requires. AutoEnginuity’s Scan Tool comes with an automated installation process, a complete and comprehensive User Guide, and an easy-to-use interface. Mini Cooper S 1 Their software includes a SpeedTracer package that provides performance data such as acceleration in 0-60 times, 1/8 mile and 1/4 mile times and top speeds, G Forces, SAE horsepower and torque vs RPM graphing and acceleration and deceleration speed vs time graphing. It also computes volumetric efficiency, fuel consumption MPG (actual and average), monitors boost pressure and quite a bit more.

At about $250 (excluding the laptop or hand-held), for the basic system, they also have an enhanced interface (additional $230) that supports sensors and bi-directional controls selected from the engine (DME), transmission (EGS), ABS, airbags, and other body and chassis systems. It comes with one of the largest manufacturer specific trouble code library of all PC/PDA-based scan tools (16,000+) and includes the all of the BMW products as well as MINI. Mini Cooper S 2 It also manages the translation of BMW FC codes into OBDII DTCs for all engine and transmission controllers. Also supported is status information regarding the fault frequency and fault conditions. Their plans are also to release the Car/Key Memory and Coding Programming in the summer of 2007.

The screens you are seeing here are from the Auto Enginuity product showing the extensive range of data that the tool extracts from the DME, CAN bus and General Body Module running on a MINI Cooper S. One has the ability to save, print, read and clear Stored and Pending P, U, B, and C Trouble Codes as well as read and clear Freeze Frame data. Mini Cooper S 3 You can view live vehicle sensors in a meter, graph, or grid format and view oxygen sensor live data and show all 11 Inspection/Maintenance systems and Mode 6 data. You can also run the vehicle, record the data and then playback your logs for offline analysis. You have full control to configure your sensors’ ranges, scaling value, audible alert triggers, units, and sampling rate.

Mini Cooper S 4Mini Cooper S 5Mini Cooper S 6

ScanGauge II

Linear-Logic offers a an alternate approach in monitoring OBD by providing an excellent ‘3-in-1’ solution with their ScanGuage II product. Its a scan tool, for troubleshooting, reading and clearing OBD II codes, a real-time gauge displaying engine and system data and a Trip Computer capable of much more than the on board computer in the MINI.

The device is small enough to integrate on the dash, or mount below the center console. I have even seen kits to mount it above the rear-view mirror. Unlike the computer-based approach, this system is completely self-contained and connects to the OBDII port with a cable provided. It has an easy to read display that is backlit. Even the backlighting can be changed from 7 different presets or you can devise your own from over 60 possible combinations. I found the display easy to read both day and night. Sg 2-2 
 Installing is straightforward enough, you mount the gauge, route the cable and turn on the ignition and connect to the OBDII port, which is below the driver knee bolster, under the dash. The device shows that it is ‘connecting’ and then you go ahead and select the configuration that suits the MINI. You can set engine capacity, fuel tank size and as you fill the tank, how much fuel is added. This used to calculate fuel consumption, which it reports both in real-time as well as data provided in the ‘trip computer’ function.

For each mode of operation, there are four displays and you simply select what you want those four displays to show. In normal use, it will report four of the following 12 data points at any one time: Fuel Economy, Fuel Rate, Battery Voltage, Coolant Temperature, Intake Air Temperature, Engine Speed (RPM), Vehicle speed (MPH), Manifold Pressure, Engine Load, Throttle Position, Ignition Timing and whether the engine is in the Open or Closed Loop configuration. (I discussed this in a OBD Part 1). Sc 1-3It is certainly interesting to observe the efficiency of the inter-cooler as the water temperature (engine temperature) rises and the inter-cooler reduces the intake air temp as you get to a speed that provides sufficient air flow.

In the Trip Mode, the ScanGauge II is capable of displaying any four of the following in real-time: Maximum Speed, Average Speed, Maximum Coolant Temperature, Maximum RPM, Driving Time, Driving Distance, Fuel Used, Trip Fuel Economy, Distance to Empty, Time to Empty, Fuel to Empty. Its very easy to cycle through each of the four buttons to provide the information you require. It takes a couple of tankfuls of gas to get things calibrated then your set to see real-time fuel usage and accumulative trip data. In addition to real-time engine data and trip data, the unit also has extensive scan tool functions that allow you to troubleshoot your car by reading error codes, and the conditions present when the error occurred. It will also turn off the “Check Engine” light. These features go beyond just displaying and clearing all trouble codes, it will also tell you when vehicle is “Ready” to pass OBDII testingSg 3-2 It will also make and store up to 10 re-writable special codes to send to the vehicle computer although there is no documentation supporting this other than how to accomplish this. In-fact, if I had to find any criticism of this great product, it would have to be the manual. Which is jumbled and disorganized. However, as its small, only 25 pages, I would strongly recommend you read it in it’s entirety prior to use.

This really is a great tool and for the purchase price of $169, its a very affordable alternative solution for owners who are wanting the features of an On-Board Computer although I must state that it provides much more data and storage capability than the MINI OBC option and is a great addition to any MINI even those with the OBC.

So this concludes the OBD II’s history, development and applications and hopefully has provided you with an insight to this portal into your MINIs on-board systems.



  1. Berthil said about 19 hours later:

    I have the AutoEnginuity and looking for a build in system to read OBD data whiel driving. The AutoEnginuity PDA enhancement is an option I am contemplating.

    For me the Scangauge is not an option because I want to read the temperature of the compressed air and knock values to see if knocking occurs. These values are present in the OBD of Mini, but unfortunately Scangauge can’t be programmed to read them.

  2. murmini said 1 day later:

    Berthi: I think the best solution and safest, maybe to use a PDA with the AutoEnginuity software and use their recording function, which will capture all of tha car’s data, then alow you to analize it later. This will provide a complete picture of the engine’s systems under true operational conditions.

  3. Mark G said 30 days later:

    I put my Mini in to the dealer today for a key code and they couldn’t talk to the car with their diag machine. This is the second time we’ve had this problem. first time it was for an airbag light, I had a local guy put the light out and he had no troubles.

    The dealer let slip today that they aren’t getting anything from pin 7 on the OBD connector (which apparantly should be the same as pin 15). I was hoping this would be a simple CAN fault, looking at your diagram Pin 7 is an Iso connector.

    Have you heard of this before or have any ideas what the fault may be as the Mini dealers are asking for 5 days to fix it?!

    I’ve explained this in more detail on the link below if you care to look please. http://www.mini2.com/forum/faults-fixes/139102-mini-dealer-cant-fix-my-mini.html#post2980054

    Any help is much appreciated Thanks Mark G

  4. murmini said about 1 month later:

    Mark,  Pin 7 is ISO 9141 -2 K line and Pin 15 is ISO 9141 -2 L line and are not the same. Before a diagnostic instrument can communicate with MINI, a communications link must be initialized. The initialization sequence permits the two parties, the off-board tester and the on-board computer, to recognize each another and establish the means by which they will communicate. It may be that your guy with the OBD reset may just be resetting the error code in the EMS and not clearing it in the MRS (Multiple Restraint System) module. This device is located between the two seats under the hand brake and communicates with the General Module via the K-Bus and subsequently the OBD via the DS-2 bus.

    The TX and RX you noted is correct. The K-line (PIN 7) is bidirectional line many messages in tha car are transmitted on it (so it is the receive line (RX). The L-line is unidirectional, and only the off-board test gear can transmit on it (TX).  So the fact there is no signal on the K-Line indicates the car is just not sending anything (faulty module?). Now, you should realize, these are not just volts/no volts. It uses the Universal Asynchronous Receiver Transmitter, similar to that found in any RS-232 communications device. So its not easy to determine what is going on without the correct tools. (I do have the complete protocol if you want it).

    You are absolutely correct in assessing that the MINI tech is not ‘getting it’ !  It is prety complex stuff and in their defense, they are trained to handle the more regular issues. 

    My first question would be is your MINI sending out any messages on Pin 7?  You will need a data reader or diagnostic device with some sophistication, but if it is not, then there is an issue with a part of one of your on-board modules.  Please let me know what you discover, we are all learning here.

  5. Mark G said about 1 month later:

    If I was to connect a multi meter from pin 7 across and earth would I be able to read an average voltage on the line?

    I have access to an osciliscope, but without knowing what patterns to expect its pretty usless. Would it be a similar pattern to a CAN line?

  6. murmini said about 1 month later:

    Mark: You can’t really gather anything from making voltage measurements. You need to be able to view the signal and then decode it using an analyzerl. There are some kits you can build that will decode the data streams and display them via an RS 232 serial port on a computer. I will send you some links and also provide you with the actual data protocols.

    My sense is that one of the many modules in your MINI is misbehaving and generating either garbage on the bus on not generating the correct signals. The MINI service shop will probably just want to replace the General Module, followed by the MRS module and then the DME module. A very expensive operation to say the least as you are out of warranty.

    Its very hard to get the inside scoop on the manufacturers deviations from the industry protocols but fortunately MINI employed much of the BMW 3 series system and there is a lot of documntation available on-line. I will email you some stuff.

  7. Jonathan S said 7 months later:


    Thank you very much for all the great info. I had a very goos time reading your articles. I just bought a Mini Cooper S R56 for everyday use. I have a question: I have the BMW INPA system which is some kind of GT1 “Lite” i’m using it for my Supercharged E46 M3 550 HP. In the latest software version i can see that the R56 mini cooper is supported. Unfortunately when i try to communicate with my mini it doesn’t work. It tells me that there is a faulty connection. Please can you lead me to some theories. I’m wondering if the OBD2 protocole was the same than in the E46.

    Thank you

  8. Jonathan S said 7 months later:


    To summarize: I just bought a Euro Spec mini Copper S R56 for eveyday use. Beside of that i own a Supercharged E46 M3 550 HP.

    My Porblem: I have the BMW INPA system which i use for my M3. In the latest version i can see that it supports R56 unfortunately when i try to read the error codes it tells me that “No response from control module”. What is weird is that it seems that it’s connected. I can have the vehicule information and the lights that indicates that the car is connected and that the engine is running are on. I saw on some forums that this problem has already occured to some other persons who brang their car to the dealers whom said that they cannot communicate with the car.

    Please can you help me!?

  9. murmini said 7 months later:

    Jonathan: this is a tricky one! There are a number of reasons why it isn't communicating. Are you using a recent version of the software/firmware in the INPA unit? There have been significant changes the the R53 product especially in the ECU functionality. I would recommend that you post your question in the BMW I-Bus group on Yahoo. While this is not specifically an I-Bus issue, there are some very good resources within it's membership that can probably guide you well on this question.

  10. Oli Mortimer said about 1 year later:

    Hi murmini,

    Do you know if there’s anything available to allow a MINI owner to enable / disable displays on the MINI OBC – ie, current speed, current consumption etc?

    After speaking with a number of owners, people have different things on their OBC, and some people are missing them…although own the same model / year MINI.

    If you could email me your response, that would be great!

    Many thanks,

    Oli Mortimer

  11. frufflefeathers said about 1 year later:

    I’m not sure this is the right place to ask, but does anyone know how to get service for a mini in Savannah? I think I need a water pump.

  12. murmni said about 1 year later:

    Yes, there are a couple of very good options in Savannah. I would strongly recommend:

    Jim Crumley who’s shop is located at:
    Savannah Tire
    4318 Waters Avenue
    Savannah GA.31404

    Autobahn Service Center
    2109 Norwood Ave
    Savannah, GA 31406

  13. mccoyrd820@comcast.net said about 1 year later:

    i have a 2003 mini s and the air bag lite is on dose any one have any idea ? thanks

  14. murmini said about 1 year later:

    Not quite sure what you mean by ‘on dose’ but airbag lights need o be diagnosed by the dealer. They usually indicate an issue in the bags deployment readiness and one doesn’t want to mess with that.

  15. Edward L Burberry said about 1 year later:

    From what I have read on your site it is apparent that you know more about the MINI electrical system than anyone that I have found. I Am having a proplem with the power steering on my 2004 Mini Cooper S. I have replaced the PS Pump and the PS Rack and still no power Steering. The PS fan runs when it should and I have a ground, constant hot, switched hot and alternator hot. Does the EHPS receive any signals from the K-Bus and if so what sensors tell the ECM what to send? From what I have been able to find the PS Pump only works when you turn the steering wheel and is speed sensitive. What tells the PS Pump to run and how fast to run? If you can answer these questions I will be forever greatful to you. THANKS

  16. murmini said about 1 year later:

    Well, this is what I can tell you. The fan control module (EHPS) is fed from the Relay, Fan, Steering Control module and fed with power from fuse F41. This is also controlled by a switching unit which controls the 2-stage fan. This control unit also receives a signal from the coolant temperature sensor.

    So I would deduce that as the engine warms up, it assumes that the PS fluid does the same. That deduction is actually made in the DME. So to answer your question, subject to coolant temp, the Steering Control module tells the PS pump what to do.

  17. Beaver said about 1 year later:

    I just got the autoenginuity with the enhanced bmw features. Its pretty nice. Because I removed the passenger seat on a semi-permanent basis, I used the tool to clear the 3 errors from the seat belt, weight sensor, and passenger seat airbag. I have a 4ohm resistor looping into the yellow airbag socket. the codes cleared fine, but the airbag light and the weight sensor and passenger code keep coming back. If I make more shunts for the other 2 plugs, will that disable the dash light?

  18. murmini said about 1 year later:

    I am not sure. The 4 ohm resistor surprises me, does that mean is simply looks for that much resistance on the circuit? I would have though the airbag module was looking for more. Really not sure where you will have to go with this. I rode with Brad Davis in his SCCA racing MINI recently and he had all kinds of dash alarm lights on and had not been able to clear them. Maybe someone else can ‘chip in’.

  19. Beaver said about 1 year later:

    I had found an online article of clearing the airbag light with the 4 ohm resistor. once the enginuity was hooked up it read all 3 as having a short to ground with about 3 ohm under the voltage in the live sensor, once shunt was in place for the airbag and code reset, it no longer showed any fault for the airbag allowing for the airbag system to safely deploy if needed. However, without resistors in the other 2 sockets, they still set off the dash light, mainly for the weight sensor I’d figure. I’ll try more shunts to bypass the weight sensor and belt tensioner and let you know. Good write up here by the way.

  20. Paul said about 1 year later:

    Hi can you help, I had a problem with the air flow which made the engine light to come on, I have since fixed the problem, how can I reset the computer to its original settings?????

  21. murmini said about 1 year later:

    Paul: Your going to need to get your hands on a code reader that will allow you to (a) read any error codes and (b) clear any error codes after the problem has been dealt with.How did you first determine the error code when the light first came on? If you have access to a code reader, then you can use it to clear the code as well. You can obtain an inexpensive OBD II code reader from most auto stores. It is always a useful thing to have. Hope this helps.

  22. andrew said about 1 year later:

    Hey, just saw this and was wondering if you could email me the complete spec as you have offered to do to others.. I have a 2002 Mini S, and plan to build my own OBD II reader device and use it for a project in one of my circuit design classes.. Thanks a lot

  23. murmini said about 1 year later:

    Well Andrew, I am afraid it is not going to be that easy. You need to do some reading from a variety of sources. The actual written technical specs are scattered a bit, to say the least. Start with the OBDII Background. Then move onto the ISO 15765 (CAN) Standards which are nicely gathered up here. If your employing the ELM 32x chipset you will need to research all of the commands such as: Set Timeout, Packed Data, Echo Off, Line Feeds. You may just want to purchase an ELM32 tool that could be read from a USB and then develop your own software. You may want to try the BMWIBus group on Yahoo. Please let me know how you get on.

  24. MINI101 said about 1 year later:

    I’ve been having the same problem trying to connect to a MINI with INPA…. I was only able to connect to the DME module, nothing else in the vehicle…

    After reviewing the OBD2 connector & wiring diagrams i see they have 2 separate K-buses. Pin 7 on the OBD2 connector just goes to the DME only! Pin 8 connects to the other k-bus which has the central electronics module etc on it…

    I’ve made up a new cable, going to test it this afternoon….

  25. murmini said about 1 year later:

    Thanks for the comment, please post your results, I would interested. There are some good resources on line: try BMW Forums and also a good Yahoo Group Called Hack the Bus – try those for some good info.

  26. bri said over 2 years later:

    I have an Actron OBD scanner, connected properly, but it won’t “link up” with the Cooper in either KOEO or KOER modes. Any thoughts?

  27. murmini said over 2 years later:

    Not sure what to suggest. OBD scanners follow a very well documented protocol. The two modes you mention are key Off Engine On and Engine Off modes. Check your Actron documentation for any another setting or adjustments you should make to your scanner’s settings. Also try and test it with another vehicle to make sure your scanner is ok.

  28. Ben Cooper s said over 3 years later:

    I recently replaced my fuel filter and cant start the engine. I can hear the pump and the lines around the tank are pressurized. However, the line to the fuel rail is not pressurized.

    Do I have a leak or is something seriously broken? Thanks!

  29. Ben Cooper s said over 3 years later:

    I then checked OBD using speedeometer and the code that I got was 672800. This code isnt familiar to me? What do I do? Is this code related to my fuel issue?

  30. murmini said over 3 years later:

    Sounds like there is some air in the lines. The fuel filter is a lifetime filter and is located in the tank. It has a zero service interval, that is it should never have to be replaced. Is this what you removed/replaced?

  31. Ben Cooper s said over 3 years later:

    I replaced it as I was having starting issues to begin with. I keep going over it again and again pulling it out and checking the seals. Seems the O ring isnt seating properly so will replace and try again. What else would stop fuel pressure into the line connected to the filter housing? Thanks!

  32. murmini said over 3 years later:

    I would still argue that your fuel filter may NOT have been the original problem. Put it all back together Starting problems may very well be fuel-related you must check fuel delivery volume and pressure as a fundamental part of this diagnosis. I know its basics but to start you need air, fuel and spark. Start from the basics.. I think your going to need to go back read the error codes. If your reader isn’t capable of reading it – have someone who has an analyzer at least identify what the issue is. For everyone’s benefit Ben, please report back on your findings.

  33. Ben Cooper s said over 3 years later:

    Ive since bought another fuel filter kit this time OEM and the O ring seemed smaller and fitted very snug onto the fuel filter cannister.

    Car starts better than before and will monitor it. No more codes. I can only guess that I got a dud O ring the first time round.


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