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11 votes
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Do fault codes get recorded with a time stamp into a log with a history of DTCs?

It really depends on the implementation of OBD2. What my 1997 Subaru logs (virtually nothing) compared to a 2015 Chevy Cruise are entirely different things. However, in most cases, a Diagnostic ...
SteveRacer's user avatar
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11 votes

How do I go about troubleshooting DTC codes?

The computers in a car are constantly monitoring the operating conditions and sensors that are in the car. When a test fails or something goes out of a pre specified range a DTC is set. The biggest ...
vini_i's user avatar
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7 votes
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Are widebands known to go lazy over time?

We found at least two issues The air filter housing wasn't forming a proper seal with the MAF sensor This engine boasts a quirky design where the MAF sensor sits at the back of the engine. The air ...
Zaid's user avatar
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5 votes

Is the vehicle code gone or does a mechanic have to clear it?

If you're worried about the car passing emissions testing, seeing the check engine light go off is a good sign. Where I live, you can't be failed because the light used to be on. The status of the ...
Bob Cross's user avatar
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5 votes
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Can lack of oil cause P0300 Random Misfire?

There's nothing that detects whether the plugs are actually igniting the mix evenly, it is inferred from the acceleration that the crankshaft undergoes each time a cylinder fires. There's plenty of ...
Phil G's user avatar
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4 votes
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P2104 Throttle Actuator Control System Forced Idle error, but car runs fine

Double check your code, Mitchell doesn't list a P2104 for the Aveo. This code also seems to be specific to Fords. Problems with the TAC after jump starts are caused by the initial low battery voltage ...
Ben's user avatar
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4 votes

Do fault codes get recorded with a time stamp into a log with a history of DTCs?

There are two kinds of fault codes; single trip and two trip. A single trip fault code is generally a major failure like a severe misfire. This will illuminate the check engine light immediately ...
vini_i's user avatar
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4 votes

How do I go about troubleshooting DTC codes?

For the DIY mechanic without access to sites like Alldata or the experience of a professional mechanic, I'd like to add a third option to @vini_i's answer, and that is a simple google search with your ...
rviertel's user avatar
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3 votes
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Is hot desert weather the source of my recurring car problem?

My immediate idea was that P0506 means there is a vacuum leak somewhere. I googled for P0506, and the first page I found also mentions vacuum leak as the first possible cause of failure: https://www....
juhist's user avatar
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3 votes

Replace or Repair Mazda MPV 2000 faulty ECU?

I'd advise against repairing ECU's, and splurging on a brand-spanking new one is, in my opinion, excessive. Get one from the junkyard, make sure the vehicle you are pulling it from has the exact same ...
tlhIngan's user avatar
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3 votes

1999 Subaru Forester - bad acceleration, rough shifting

I'm leaning towards the throttle position sensor being out of adjustment/bad or a bad mass airflow sensor. Perform a volumetric efficiency test, record your IAT in °F, RPM and MAF in g/s. Use an ...
Ben's user avatar
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3 votes

Jeep Wrangler spark-plug issue

Sounds to me like one of the spark plug wires isn't fully seated. I would check both ends of each cable and make sure they're fully seated. The engine code it produced should give you some idea where ...
Paul Dufresne's user avatar
3 votes

How to fix P1167 in a 2001 Honda Accord, with a F23A4 engine

This is assuming you don't have access to a scantool that can communicate with a Honda ECM and without bidirectional controls. Key On Engine Running (this may work Key On Engine off) disconnect the ...
Ben's user avatar
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3 votes

Decoding VW Airbag DTC from elm327

First let's define your query to the ECU: 19 - ReadDTCInfo 02 - Report DTC by Status Mask 08 - Status Mask Ignore all this, it's only the module taking a moment to reply 77F 03 7F 19 78 ...
Damon Earl's user avatar
3 votes

Confusing DTC terminology?

First, if you're looking for an answer to "what does a code mean", your best bet is to just Google it. Find out what the code is telling you. This will give you a list of things it might be. ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
2 votes

How to fix P1167 in a 2001 Honda Accord, with a F23A4 engine

P1166 indicates a blown or malfunctioning heater core fuse. I know that O2 sensors have resistive elements inside that are activated when the engine is cold. O2 sensors operate more efficiently when ...
Old_Fossil's user avatar
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2 votes
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Hyundai Santa Fe 2004 3.5L Random Misfire hesitates when accelerating

The tach jumping around is likely a failing ignition failure (or misfire) sensor (IFS or IMS). It is located on top of the thermostat housing on the drivers side of the engine. The part is ~80 USD. It ...
Jamie Paterson's user avatar
2 votes

Trouble Code decoding

Your framing format looks odd, but anyways. This is the answer to 03, which is querying the diagnostic trouble codes. Stripped from the multi framing, your result is actually 03 00 59 01 54 01 55 ...
DrMickeyLauer's user avatar
2 votes

Do fault codes get recorded with a time stamp into a log with a history of DTCs?

Very detailed responses already! Just wanted to add something about emissions testing after clearing fault codes. Some manufacturers include a way to create the conditions that will determine whether ...
katch's user avatar
  • 21
2 votes

How are EVAP system leaks detected by the ECU?

The most typical system used by GM is a vacuum decay type system. The system has 3 major components (for leak detection that is); purge solenoid, vent solenoid and a pressure sensor. Under normal ...
vini_i's user avatar
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2 votes
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Replace or Repair Mazda MPV 2000 faulty ECU?

It is much more likely that the IMRC is damaged. The voltage on the line between pin 1 and pin 42 is provided by the IMRC. The PCM then pulls that voltage to ground to turn the IMRC on. When the ...
vini_i's user avatar
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2 votes
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Would my 2005 Focus's computer have a memory of past faults?

If the computer hasn't been cleared and it has had power the whole time (no battery failures), it might be an old engine code ... but considering what you got done, I'm doubting it. If I got a car ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
2 votes

Diagnosing silent misfires

You can do what the mechanic should have done and test the cylinder balance, ignition, injection and compression to fully diagnose the misfire. Use this guide as a reference, its fairly comprehensive ...
Sam Basso's user avatar
  • 474
2 votes
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If the check engine light is off does than mean your car is fine?

So I'll start by answering your question listed at the end. First off, while there is a small level of standardization amongst OBD2 reported codes, there isn't standardization as to what sets these ...
Techlord's user avatar
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2 votes
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Test is inhibited by other DTC?

As your vehicle operates, the Electronic Control Unit (ECU) and other control modules (ABS) are constantly running tests to ensure various systems are operating correctly. These tests are run at ...
Kevin A's user avatar
  • 166
2 votes

Do fault codes get recorded and stored with a time stamp and date into a master log with a history of DTCs?

No. Most codes are volatile. There aren't any date stamps on anything, so if one pops up, you won't know when exactly it happens. Codes are meant as an indicator. Once the issue is no longer present, ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
1 vote
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DTC checking while engine running

In the two links you provided in comments, it states to plug in your code reader, turn the ignition on, but don't start the engine, then read the codes. It's not telling you "cannot run the engine" ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
1 vote
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GM P0420 Code - Eliminating Possible Causes in Chevy G10

Your question is a bit confusing. "Is it possible for a fault with a specific sensor to trigger this P04020 error code, rather than a code specific to that sensor?" I think you are asking if sensors ...
Carguy's user avatar
  • 1,992
1 vote

Classifying a DTC as active, past or potential

EDIT: I spent more time reading into this, the individual manufacturer of the vehicle has a lot of control over this. The OBD2 DTC has some standard items but is not required to have a time stamp or ...
finleyarcher's user avatar
1 vote

Not receiving multi line response ELM 327

you need to send 30 00 00 00 00 00 00 00 to get the remaining response frames
Luis Costa's user avatar

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