Questions tagged [diagnostics]

Use this tag for generic questions related to tools, techniques and methodologies for diagnosing problems. Do not use this tag for case-specific problems, the "troubleshooting" tag is better suited for that.

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37 views

mechanic can't reproduce trouble when car is at shop… need to record OBD data when problem occurs while driving

I brought my car in for servicing, but the mechanic can't reproduce the problem. I want to log OBD data as the problem occurs. I would then provide this captured data with the car when it goes back ...
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21 views

What's a good field manual book for Auto Diagnostics/electrics?

For European cars. I'm looking at this from a purely practical point of view, rather than theory, and for someone who already has decent machine electrical fault finding experience. Thanks
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40 views

Is there a non-USB-OBD2 adapter made for reprogramming (CAN/ISOTP)?

I'm working on an ECU reprogramming and coding app (iOS, Android, etc.) for a client who is part of the automotive tuning scene. I have been trying out dozens of OBD2 adapters, but most of them fall ...
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38 views

Won't go when out in gear [closed]

I have a 1500 Suzuki intruder that I changed oil oil filter and gear lube on Plus changed plugs now when I put it in first it dies why
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35 views

Can an OBD2 tester do a battery load test?

This Autophix device device was suggested by a review as the best of five battery testers. The text implied that includes testing cranking amps. But it can only connect to the computer—has no way to ...
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650 views

Fuel rail pressure - how long should it hold?

My factory service manual states fuel pressure should be 50 psi with the engine running at idle. This is a six cylinder 2008 Subaru 3.0R engine with a return-less fuel line to the injectors. ...
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15 views

4cy automatic 1997 Toyota Camry. The windows won’t roll down and car will not start. The alarm keeps going off

I have a 1997 Toyota Camry. After installing a new battery the cars alarm is going off and will not start it just cranks. I can’t even roll the windows down or unlock the doors. Any help
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39 views

how to check car for impending failures? [closed]

My kia Sorento 2007 failed on me multiple times. Each time disabling the car and putting the driver in danger harmonic balancer alternator radiator and water pump in each of those failures, I had ...
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35 views

Can faulty relays cause fluctuating run performance or will they either be on, off or intermittent?

Car is experiencing reduced performance as well as stalling. Assuming these are caused by the same issue is it fair to say it cannot be a relay. Reason is because, as far as I’m aware, a main relay ...
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1answer
96 views

How to diagnose if battery is faulty or alternator is faulty

Little Background: I own 2016 Mazda CX-5, battery that came with car was not holding the charge for long, so after some research on which battery to replace it with, I decided to replace it with ...
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108 views

Peugeot 207, Head gasket blown?

4 vti coolant has a brownish color and its oily to the touch. I did an oil change about two weeks ago, I'm wondering if it could be connected, the coolant level didn't really budge. I remember the ...
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1answer
40 views

Sad, whiny, stressed out, constipated noise when AC is on. Is it dangerous?

Another hot one today... I noticed in my Ford 5.4 v8 1998 van, when my AC is in the process of workin (like in the time between when it clicks on and clicks off), if I'm driving at certain speeds (...
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79 views

Which DLC terminals are known as DLC bias terminals (or should it be DLC Bus terminals)

This is related to Test 5 of this question: OBD II Scanner refuses to communicate with the vehicle! Funny that I should be asking this but then .....it happens Unfortunately, I cannot remember. I'd ...
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71 views

Engine diagnostics after engine sucked in water

I have a Great Wall V200 turbo diesel. I was four wheel driving one day when I went through a bit of water. The water came up over the bonnet due to the bow wave. After getting through the water, the ...
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1answer
23 views

98 Toyota Camry: Will night rear light failure trip check engine light?

A number of faults can trip the check engine dashboard indicator and must be checked with an ODB meter to decisively identify the fault. I was just informed that "the car's nighttime rear lights don'...
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2answers
31 views

98 Camry: Check Engine Light at 90K miles [closed]

What is the procedure to address the root cause of the check engine light? Does it make sense to purchase an OBD meter or should some other diagnostic be performed first?
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22 views

2005 Ford Explorer check engine cod P0446

I have a 2005 Ford Explorer that has a check engine code P0446 which reads as Evap container system vent check malfunction. How do I repair this and where do I start?
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202 views

Mazda 323 (BJ) 1,5i 16v 1999: OBDI - OBDII ve ELM327

Mazda 323 (BJ) 1,5i 16v 1999 I have a vehicle. I know it uses 17 Pins ODBI. By connecting this to the ELM327 somehow, I want to find the error codes in the vehicle and search for its solution. The ...
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30 views

Can I learn anything about a misfiring cylinder from the fact that the dialectric grease around the plug is discolored?

On the way to the in-laws yesterday my 2008 fusion started bucking. Code reader says I'm misfiring on cylinder 2. I popped off the coil boots thinking I'd swap them and see if the problem cylinder ...
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26 views

Manual calculation of engine load [duplicate]

Calculated engine load (PID $04) is determined (according to SAE J1979) by equation: LOAD_PCT = [current airflow] / [(peak airflow at WOT@STP as a function of rpm) * (BARO/29.92) * SQRT(298/(AAT+...
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28 views

Drop down to zero during ride

Randomly during ride, the "D" from transmission indicator disappears for 2-3 seconds, during this time the car like switched to neutral (RPM raise without acceleration of the car). In the beginning ...
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1answer
103 views

Siemens sim2k-34vr ecu parametrs and service ids

I need to read parametres like RPM of the engine from siemens sim2k-34vr ECU from obd2 port through K-line protocol,I tried standard service id 0x01 to read current data but ECU said 0x01 service id ...
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1answer
173 views

Can you see what version of ELM327 an OBD2 diagnostic scan tool/fault code reader supports?

According to https://en.wikipedia.org/wiki/ELM327#Other_Versions there is a handful of different versions of ELM327. If you buy a non-genuine ELM327-device (that is, something that is compatible with ...
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261 views

Nissan Qashqai “Test Mode”: What does the data mean?

I learned about a "test mode" for the display, which can be used for diagnostics, without an obd reader. I managed to get inside the test mode, but I am baffled by the data and am not sure what it ...
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1answer
417 views

Chevy 3.5 engine tick

I have a 08 Chevrolet Impala with a 3.5 with 70k miles. There is a tick that corresponds to engine speed. It's a pronounced tick but I highly doubt its piston slap or rod knock. It seemed like an ...
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14 views

Konnwei kw30 diagnostic equipment

Just got a konnwei kw830 diagnostic tool I plug it into my car which I know has a fault as I have checked on another system and that comes up with fault key 1 which means my car key has lost its ...
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2answers
77 views

What things cannot be tested(except by elimination) when trying to diagnose a sluggish engine?

As far as I'm aware there are certain things that cannot really be diagnosed if you have a sluggish engine and so you can only find them by elimination. As an example if you test a car due to ...
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1answer
63 views

What things are tested during a diagnosis for a sluggsh engine?

I enquired at both dealer and garage about diagnosing my car for being a bit sluggish and less peppy. Both said it usually takes one hour to find the problem\narrow it down for such a matter. I'm ...
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1answer
134 views

How difficult is it to collect obd commands ?Will it be different for different brands?

OBD is something very interesting I found these days.Thanks to this repo https://github.com/pires/obd-java-api & wikipedia which provides the basic information of PIDs.But there is a lot of ...
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1answer
409 views

Exactly how much refrigerant is in there?

A concern that comes up regularly when troubleshooting A/C problems is whether an A/C system has too little refrigerant (hello leaks) or too much of it (hello overcharging). The traditional way to do ...
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82 views

Why is this RPM graph squarewave?

'07 Subaru Outback 3.0R 5 speed auto. I am logging using the excellent RomRaider and was kind of surprised that when graphed RPM looks like a square wave in most situations, don't know if it was ...
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2answers
111 views

Need Help Diagnosing and Fixing my Kawasaki Ninja

First time poster here. I have a 2010 Kawasaki Ninja 250 - this is a bit of a story and I try and keep it short. A couple weeks ago my bike was having trouble - when I would rev the engine in low ...
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1answer
55 views

My Octavia 1.9 TDI 2004 not won't cross 120km

My car would not cross 120 km. What is the problem? What is maximum speed of the 2004 Octavia 1.9 TDI engine superup
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1answer
566 views

Are mineral oil smoke test machines sensor safe?

So there's heaps of DIY smoke test machines demonstrated around the web. I learned to built one of these, was kinda fun. It worked, even found a crack on my air intake that was messing with the ...
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1answer
150 views

Need help with diagnosing weak AC on ford explorer

2007 Explorer has weak AC. When driving at speed, the AC can produce reasonably cool air. When stopped at traffic lights or such, the air warms to ambient temps rather quickly. I hooked up the ...
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78 views

Check engine light won't stay off

I've attempted to get my check engine light fixed a couple times and at each repair facility they've scanned the code and told me it was a bad oxygen sensor. I had the oxygen sensor replaced at both ...
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3answers
287 views

Brake problems with 1991 Toyota Celica

I have no brakes. I have bled the brakes, changed the pads and calipers, brake hose. The front driver side bled with no problems but the passenger won't. What else could it be? I've also replaced the ...
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4k views

Replaced transmission now car wont start

Had my transmission replaced drove car for three days now it won't start. Lights and radio work. No crank no start. Replaced battery, starter, and starter relay. PLEASE HELP HAVEN'T HAD MY CAR A YEAR ...
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253 views

2006 Mazda MX-5 P0126 + B1318

2006 MX-5 57k Miles USDM 2.0L 6-Speed P0126 and B1318 Set but no light on/Sporadic illumination. Coolant reservoir is full. https://www.obd-codes.com/p0126 That site references that there's a TSB ...
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2answers
506 views

Toyota Vitz 2007: Can a vacuum leak lead to PO171

In my Toyota Vitz 2007 (Yaris in some countries), I sometimes get a PO171 (System too lean) trouble code when the vehicle is idling in a traffic. When my mechanic scanned the vehicle for trouble ...
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2answers
101 views

Electrical Diagnostic Procedural Lists [closed]

Post your general/specific Testing/Diagnostics Procedural Lists for Automotive Electrical Systems. These procedures are intended to target vehicles with modern 12V systems. The format of the site ...
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3answers
138 views

Developing an OBD2 application - Engine Warning Lights

I am currently developing an application which retrieves diagnostic trouble codes from my car's OBD system and display any DTCs in a list. However, as my car has no trouble codes I am unable to test ...
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1answer
106 views

Diagnostic connector broken; wires corroded and pulled out of the housing

1990 f150, XLT Lariat. Has been having idling issues, and the check engine light flicked on. I went to try and pull codes off, and realized that the wires inside the diagnostic connector had corroded. ...
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2answers
16k views

DTC checking while engine running

Why it is said that DTC (Diagnostic Trouble Code) should not be checked when the engine is running?
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1answer
3k views

Sniffing the CANbus on an Audi A5

I've asked a similar question before: Connecting to car CANbus Unfortunately I haven't progressed much. The first product I tried was a CANLogger 2000, I got nowhere with it, so I sent it back. ...
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2answers
2k views

OBD-II Fuel type and level of Monofuel Cars

I'm making an application like Torque and i have some issues with commands of Fuel Type and Fuel level with cars that use only one type of fuel like, Only Diesel or only gasoline. With car Bifuel ...
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1answer
4k views

Infrequently sticking clutch in 08 VW GTI

I have owned my 2008 GTI MKV FSI for the past 4 years. For the first ~8k miles (bought at 42k), everything behaved as expected and performed nicely. At a certain point around 50k, I noticed that the ...
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296 views

How do I diagnose a blinking overdrive off light on a 2001 Ford F-150 with 4R70W transmission?

Today the "OFF" light on the transmission shifter starting blinking on my 2001 Ford F-150. It is the 4.6L with a 4R70W transmission. I pulled the codes but all I found was "Evap system inoperative" ...
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1answer
272 views

Not receiving multi line response ELM 327

I am sending the following commands to my Hyundai i20 2012 model (OBDLink SX Bluetooth device): AT Z AT H1 AT L1 AT S1 AT AL AT SP6 AT SH 7D1 18 00 FF 00 The response I am getting is 7D9 10 0B 58 03 ...
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1answer
452 views

How do I diagnose trouble code P0567 OBD-II in my car and what are its causes? Which component of cruise control system should be checked first?

I am getting issue with my car's cruise control system, and while diagnosing, this code is shown, I want to know the reason and meaning of this code.