On-Board Diagnostics-II (OBD-II). Questions usually involve scan tools, their use and their compatibility, as well as how to interpret Diagnostic Trouble Codes (DTCs).

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14
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2answers
761 views

Difference between OBDII and CAN

What is CAN (controller area network)? What are the differences between an OBD-II protocol and a CAN setup?` How do I use an OBD-II scanner on a vehicle with CAN?
14
votes
3answers
3k views

Can a vehicle be harmed with bad inputs via an OBD-2 port?

I bought a cheap (sub $10) ELM 327 Bluetooth clone OBD-2 diagnostic adapter on a local "ebay-style" market where the seller specializes in car diagnostics and has several thousand positive reviews ...
14
votes
3answers
580 views

What are good features to look for in an ODB-II reader

I recently took my car in for the engine light. It turned out to be a minor problem (crack in gas cap let water in). It would be nice to have a low-cost ODB-II reader to be able to find out for ...
13
votes
3answers
89k views

What iPhone/iPad app works best with ELM327 Bluetooth OBD-II reader?

I've found a number of apps for the iPhone/iPad that connect to ODB-II readers via WiFi, but unfortunately that means that it disables 3G and all the benefits of having a 3G device built into my dash. ...
13
votes
1answer
2k views

How do I find the correct pins in a CAN-BUS connector?

This question might be too technical for this forum, but I'll give it a go. I have a 2012 BMW R1200R motorcycle with CAN-BUS. I'd like to make an Arduino interface to the connector on the bike, but I ...
12
votes
3answers
956 views

What to know before buying and OBD-II reader

I read the features to look for in an OBD-II reader, but I am curious if getting one is the right move. I'm just planning to get a cheap one, which is proving to be interesting shopping local. What I ...
11
votes
2answers
92 views

What is the motorcycle equivalent of OBD-II?

I once met an OBD-II expert while traveling and asked him if motorcycles (especially the fuel-injected ones) employ a similar protocol. He said that the use of such a protocol is not as widespread ...
11
votes
1answer
72 views

Are there any plans to update OBD-II?

OBD-II is ancient It predates the Porsche 911 GT1, Windows 95 and implementation of the Schengen Agreement. I would have thought that SAE would be working to add more diagnostic coverage for ...
9
votes
2answers
1k views

Why do we need make-specific cables to read car ECUs?

I find it bizarre that the automotive industry has standardized the use of the OBDII protocol, yet most cars require make-specific cables in order to access the complete set of diagnostics and ...
9
votes
1answer
193 views

How to detect engine/ignition (on/off) status using OBD2?

My device needs to know when a car engine/ignition is started and stopped. Is it possible to get that status using OBD2? If yes, which PID will give me that information? Do I need to write any ...
8
votes
3answers
190k views

What is the pin or keycode for ELM327 bluetooth OBDII adapter?

The infamous ELM327 OBDII device came without any paper, just a crappy CD with no document related to the device (only some software and drivers thrown on the CD almost randomly). I tried the ...
8
votes
1answer
56 views

Computing Wheel Torque From Engine Torque

It seems possible to obtain engine torque and RPM from a truck CAN bus. I'd like to estimate tractive force at the wheels given these two values. How should I go about computing torque at the wheels? ...
8
votes
1answer
65 views

Received frames from vehicles with multiple ECU chips

I'm not generally a 'car person', so hopefully I can explain this well enough to get some help here: When sending messages to an OBD-II device, I receive one response in most cars I've tested. ...
7
votes
4answers
286 views

Is control module voltage and battery voltage the same?

Is the Control Module Voltage (from OBD Mode 01 PID 42) and battery voltage the same? If not, what is the relation between them? Why is the max value of Control Module Voltage (from OBD Mode 01 PID ...
7
votes
2answers
6k views

Should I replace my own oxygen sensor if i have a Check Engine Light and Code P2195?

My 2003 focus lx 2.0L L4 SOHC ~18,000 miles has had the engine light so i went to autozone to read the code. Autozone obd2 printout says "P2195 lack of heated oxygen sensor- Bank 1 Sensor 1 HO2S11 ...
7
votes
5answers
1k views

Are there any OBD II converters on the market?

I know there are tons of readers and software on the market, but what I really need is something to convert signals of my1970s sensors (fuel level, speed, coolant temp, etc) to OBD compliant signals. ...
7
votes
3answers
422 views

Calculating MPG from MAP sensor (or converting MAP data to MAF data)

My 2002 Honda Accord V6 has a Manifold Absolute Pressure sensor (MAP). I understand that this sensor gives out information in pressure units (psi or equivalent). After doing a bit of research, I ...
6
votes
4answers
5k views

Controlling door locks via CAN bus

I'm trying to figure out how to lock and unlock the doors of a 2010 Toyota RAV4 using the CAN bus via the OBD-II port. I have a microcontroller attached via an CAN controller and a CAN receiver, and ...
6
votes
1answer
62 views

ATMA on OBDII not Working

I have successfully connected a terminal android app to the obd port of my car. And tried dry run of many at commands, many are working as expected. But ATMA (AT command to Monitor All) is not ...
6
votes
1answer
272 views

OBD2 and CAN-bus

Do all vehicles with OBD2 have a CAN-bus? Otherwise, what are the alternative buses used? Are there special versions of the buses for trucks and school-buses than for cars/suv/vans?
6
votes
1answer
2k views

What is supposed to happen when my Subaru's test mode connector is hooked up?

There's an electrical connector under the dash of my 2000 Subaru Forester that is apparently instrumental in the diagnosis of some OBD-II trouble codes. It's a pair of bladed terminals like any other ...
6
votes
1answer
115 views

ODIS 5.0.6 diagnostic tool : how can I remove an option from a transformed vehicle?

We have a transformed car, a Bentley, which no longer has a motorized sunroof. The blind has also gone. However the car diagnostics exhibits a fault on the related, non-present devices and motors. We ...
6
votes
1answer
374 views

Does OBD II explicitly or implicitly include forward/reverse information?

From my understanding, OBD II does not directly tell if a car is in forward or reverse gear. I wonder what the best way to derive such information from OBD data if there is any. Following the ...
5
votes
2answers
101 views

How is barometric pressure related to emissions testing?

In the VW emissions cheating scandal, news reports say the following: According to the EPA, "the position of the steering wheel, vehicle speed, the duration of the engine's operation, and barometric ...
5
votes
2answers
819 views

Reading OBD2 too fast

I'm writing a software to make a telemetry application for my 2001 VW Golf mk4 reading parameters from OBD2 using an ELM327 compatible cable. I succeeded so far. The problem that I have now, is that ...
5
votes
2answers
39 views

Calculate amount of fuel injected

How do I calculate the amount of fuel injected (both gasoline and diesel cars). I want an instantaneous value. http://www.rceng.com/technical.aspx Websites like these ask for 'Desired Crankshaft ...
5
votes
2answers
301 views

What is the point of a vacuum pump with a fuel injection engine?

I recently got an OBD-II dongle with the Torque Android app, which allows me to read the computer's output in real time. The app will let me drag and drop different gauges on my screen, which works ...
5
votes
1answer
25 views

On-Board Diagnostics (OBD) Readiness Monitors

I would like to know how does apps like Torque calculate if my car (Hyundai i10 Era) is 'Not ready' yet? What are the factors (complete list) do one checks to decide? Is there any formula to calculate ...
5
votes
4answers
3k views

shop can't connect to onboard diagnostic system?

I've recently moved to California and am trying to get my car registered; they require a smog check (which is possibly actually more of an inspection than the name implies?). I went by a very basic ...
5
votes
1answer
661 views

OBD 2 Fuel reading says No Data

I wanted to read fuel level from the car and display it on my application. The communication was established using the ELM327 Bluetooth interface dongle. The ELM module replies NO DATA for the code ...
5
votes
0answers
45 views

Mahindra KUV 100 and Suzuki Alto OBD protocol

Can someone please tell me the OBD-ii protocol of Mahindra KUV 100 (diesel) and Suzuki Alto (diesel). Also whether ELM 327 Bluetooth will work? ...
4
votes
2answers
110 views

Any open-source OBD scanner analysis tools?

I've been having some weird problems with my '06 Pontiac G6, and finally broke down and bought a Bosch code scanner to see if the DTCs could tell me anything... they didn't. This scanner has the ...
4
votes
1answer
107 views

Is it possible to auto close the power window of a car using OBD and CAN bus?

I am not an electrical or automobile engineer, so pardon my ignorance. I found this product in the market to auto close power windows for certain brands. How can we send signals to the CAN bus using ...
4
votes
5answers
7k views

Is it worth getting an OBD2 scanning tool?

I have a Opel Corsa 1999 B type. It is giving me problems now. I have read a little bit about OBD2 scanning tools. But don't know if one could help me, or that I am maybe hoping for too much. I ...
4
votes
2answers
597 views

OBD II power when key not in ignition

I can't get to the OBD connector on my car at the moment. As far as I know the OBD II voltage is active even when the key is in lock. Can anyone confirm this? edit : It's for a product that ...
4
votes
2answers
111 views

Replacing Cam Position Sensor; any gotchas?

I have a 2007 Nissan Murano. My Check Engine light is telling me that the cam position sensor (bank 1) is bad. I've located the sensors, and they are both readily available and easy to get to. Is ...
4
votes
1answer
891 views

How much battery does an obd bluetooth reader suck?

I'm planning on using an obd bluetooth reader on my car and leaving it plugged in to use apps like dash and torque. It's a daily driver so I'm not that scared of depleting the car's battery, but I ...
4
votes
1answer
1k views

Subaru Forester OBD Scan Codes “P0130” and “P0130 P”

My 2002 Forester Check Engine light is on. I connected an Autel MaxiScan MS300 OBD-II scan tool and got indication for two codes. Browsing through the codes, it reads P0130 and P0130 P. The first one ...
4
votes
2answers
54 views

Gear ratio from speed and rpm

http://stackoverflow.com/questions/30017271/obdii-determine-gear-given-speed-and-rpm Referring to the above link, one method to find the current gear ratio is to calculate Speed/rpm (The rpm is the ...
4
votes
1answer
89 views

OBD-II reader has power but shows nothing

My check engine light is on, the car ran out of battery and after jumping it, it is running kind of poorly, idling rough, etc. I plugged in the OBD-II scanner/reader, and it "has power" (green ...
4
votes
3answers
10k views

OBD-II reader/scan tool that can also diagnose air bag light

Is there an OBD-II reader/scan tool that can also diagnose air bag warning light? My 2004 Honda Element EX has a red air bag warning light that recently has turned on. The nearest Honda dealer wants ...
4
votes
2answers
792 views

How to view error codes on a speedometer with no OBD reader?

I have a 2000 Dodge Neon and don't have a real OBD reader yet. The other day I started to turn my car on and, before I got to the ignition the speedometer came on with a "p" and a "1684" (the check ...
4
votes
1answer
23k views

'Check Engine' code P0171 System Too Lean - Is it safe to drive?

My 2003 Toyota Corolla's Check Engine Light came on. I read the codes using an OBD code reader and got P0171 - System Too Lean (Bank 1) and P0133 - 02 Circuit Slow Response (Bank 1, Sensor 1). The ...
4
votes
1answer
110 views

Quick Oil Change place overfilled my BMW Z3

Just got this car, a BMW Z3 3.0 from a Tampa dealer and have not even had it 10 days and Check Engine Light came on. I wanted to get the oil changed to full synthetic just in case it wasn't and ...
4
votes
1answer
754 views

How to interface with obd ii elm327?

Do I have to buy this in order to get all the PIDs and the full instruction set for communicating with the car's obd ii interface via an ELM327? I tried looking for some kind of api for the ELM327 ...
4
votes
1answer
30 views

Calculating AFR using injector flow rate and mass air flow

Is injector flow rate = Mass fuel flow? If so then AFR = MAF/Injector flow rate. Can someone please confirm this?
4
votes
1answer
88 views

How do I get the most out of a “smart” OBDII scanner?

I recently purchased an OBDII scanner that allows me to read and log data using my tablet. How do I get the most out of this device? I am already familiar with simply reading the trouble codes to ...
4
votes
1answer
3k views

Can I use an OBD2 Scan Tool on older GM vehicle?

I can get an adapter that connects my OBD2 scan tool to my 12 pin GM scan tool connection. But will the tool be able to read the codes and tell me anything useful? Or do I need to get a scan tool that ...
4
votes
2answers
2k views

Can an ELM327 OBD-II reader report on anything other than engine trouble codes for a Mini Cooper?

My car (Mini Cooper S) has a service light and tire pressure light on, so I was expecting my new OBD reader to tell me what they were about, but it just says "0 confirmed emissions-related DTCs ...
3
votes
3answers
5k views

Can OBD-II be used to control the vehicle?

Is the OBD-II port in vehicles only used for reading diagnostic codes or is there some functionality that allows the vehicle (eg. engine revving) to be controlled through OBD-II? Thanks.