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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1answer
213 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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2answers
61 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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0answers
24 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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1answer
91 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
33 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
88 views

Safe rounding of CCA during battery load testing

How do you determine the safe amp load of a battery tester? I am looking at testing a battery on a 2012 Mazda 3 sport which has a Mazda factory battery 75D23L (52). The service manual states in the ...
3
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1answer
114 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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0answers
37 views

Can I read PID from other protocol?

My car (Renault Megane II) sharing PIDs through KWP protocol but also sharing other data (more advanced) through CAN. Some of data which I want to read is not available through KWP (PID). Is there a ...
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0answers
13 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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1answer
122 views

Skoda Fabia 2005: what I need to know to buy a diagnostics machine?

I'd like to buy a diagnostics machine for my Skoda Fabia 2005. My issue is I'm absolutely newbie on this. I don't know which cable connection requires, if there's some standard, ... Will you provide ...
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1answer
18k views

What could be causing a grinding noise when car accelerates quickly?

My son is an hour away and we are trying to diagnose this problem on a 2001 Toyota Corolla. When the car is accelerated slowly and gradually everything is fine. However when the gas "pedal is to the ...
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18 views

Misfire data log

I'm trying to understand what is the meaning of "Misfire" in this graphs, it always starts with value 0 and then can move up to 3. Is it a sensor? if yes what exactly it measure? if not, what is it? ...
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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
43 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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1answer
343 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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4answers
21k views

Technique to test an alternator - fact or fiction?

A friend explained that the following is a simple way to test an alternator to see if it is working: Turn on the vehicle. While it is running, carefully remove one of the 12V battery leads. See if ...
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1answer
261 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.
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49 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 ...
2
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1answer
10k views

2011 Jeep Compass No-Start

Car comes in with the complaint engine cranks doesn't start. Confirm the complaint and check for codes, P0688 - ASD Relay Control Sense stored in memory. After doing a quick fuse check I found that ...
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1answer
3k views

How To Diagnose 3rd Brake Light (Without Proper Equipment)

I have a 2012 Ford Focus (sedan version). The third brake light stopped working recently and I'm trying to determine if the problem is with the light itself or inside the vehicle, but a I have very ...
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0answers
69 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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3answers
132 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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3answers
6k views

Possible EGR problem on Fiat Idea Multijet 1.3 Diesel

I've been having issues with my 56 plate Fiat Idea for a while now. It seems to drive normally up to about 2500-3000 rpm where the car lurches a little, as though i shifted down a gear, the MIL light ...
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2answers
9k 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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10answers
95k views

How can I detect vacuum leaks without access to a smoke machine?

In the course of helping my friend sort out a lean condition with his Mercedes GLK280 we have to pinpoint the source of a vacuum leak in the intake plumbing. The interwebz tend to recommend having ...
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3answers
46k views

How to diagnose the cause of no power reaching the spark plugs when power reaches everything else, after checking fuses?

I've been trying to get my long-suffering Toyota RAV4 first generation (1998) to start after numerous different problems, the latest of which I've narrowed to the spark plugs not firing seemingly due ...
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0answers
12 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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1answer
4k views

How to check if spark plugs are firing? Coil-on plugs

While trying to diagnose a tricky car not starting problem I was asked to check if the spark plugs were firing at all. I've found plenty of resources on inspecting the condition of spark plugs after ...
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1answer
96 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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1answer
62 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
50 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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3answers
118 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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1answer
2k 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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3answers
67k views

How to test for defective glow plugs?

On a diesel engine, how can I know which glow plugs are defective, and can I change these only?
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1answer
386 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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2answers
70 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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4answers
9k views

How to test a clutch

I have just bought a second hand car, and I have the feeling that the clutch is worn out. How can I do a quick clutch sanity check?
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0answers
62 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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5answers
40k views

How to diagnose high speed vibration?

I get a vibration at high speeds (50+), can feel it particularly in the steering wheel, front seats, dashboard. I have been trying to figure out what's going on, keeping in mind that: All 4 shocks ...
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0answers
2k 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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3answers
7k views

Best practice to tell if an interference engine has bent valves?

I have a 2003 Mitsubishi Galant 2.4L SOHC engine with 251k miles on it. While I was driving it all of sudden the engine just died. I pulled off the road and then had it towed to a local mechanic. ...
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0answers
220 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
333 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
84 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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1answer
58 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
1k 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
3k 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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0answers
237 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
4k views

Why does my truck die when I have the ac running?

So my 2003 Chevy Trailblazer dies when I have the AC running. When I'm idling mostly (at a red light or stop sign) and it's died a couple times while driving at a low speed (thru a parking lot). ...
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4answers
5k views

Suzuki sv650s will not start, no lights, no fuel pump, nothing

My sv650s will not start at all. I put the key in the ignition and turn it on and none of my accessory lights come on and the fuel pump doesn't engage. It's done this before and I fixed it originally ...