General > General Technical Chat

Murphy’s Law with my OBD2 reader

(1/13) > >>

edy:
So last week in the midst of the crazy bomb cyclone of the American north east, my car decided for the first time ever to spring up a “Engine Light” (Honda CR-V 2011). At first I panicked thinking I have to immediately run to a mechanic, but then once I started reading up on it I found it could be one of a million different things, from as simple as a loose seal on a gas tank cover, to oxygen sensors and various other engine components.

Not having any information at all I started doing all the simple checks I could, tightening the gas cap, checking for loose connections, checking for leaks or low levels of fluids, you know basic stuff. I drove the car around and didn’t notice much difference. It’s old and sluggish and has always been. But I decided to order an OBD2 reader to see what is going on just so when I show up at a mechanic I have some idea so they don’t try to sell me a bag of goods I didn’t ask for.

Anyways, as luck would have it I received my OBD2 reader today in the mail from Amazon. I was just about to open it and try it out when I needed to run an errand and lo and behold… the freakin’ engine light reset itself!!!! It turned off!!!   :-DD  Freakin’ Murphy at it again!!!  I didn’t even have a chance to open the package, just the mere presence of the OBD2 reader scared my car into submission!!!  :-DD

So I’m going to keep this OBD2 reader anyways but my question is, does it look at past codes? Is there any memory of past faults or any historical data stored in OBD2 if I hook it up now that the engine light is off? I would just like to know what it could have been. I don’t know if cars record or log these things. I guess I’m happy the engine light turned off and I need to go for a “Service B” anyways.

jmelson:
Almost certainly a 2011 car will have a history of past codes.  You will need a guide to tell you what those hex codes actually mean.
Jon

gnuarm:
Fixing the condition, typically does not reset the displayed code... at least, not for a while. 

I seem to recall having error codes that indicated misfires on a couple of cylinders.  It would periodically come and go.  I eventually figured out it was worn out spark plugs.  They would only miss when the engine was under heavy loads or something.  So if I didn't push it for a couple of weeks or so, it would reset itself. 

I don't think they have an OBD II on my current car.

tom66:
I had a problem with diesel car a long while ago (Peugeot 206 HDi).

I was driving on the motorway at 70 mph and suddenly the car began to slow down and the check engine light came on.  It would not go any faster than about 35 mph and the engine revs would not go past 2000 rpm.  Not great especially given the heavy traffic and weather, so I pulled over as soon as I could.

Restarted the car, MIL was still lit, but performance was restored.  Merged back onto the motorway and a few minutes later again, the power cut out.  So pulled over again, and restarted it. 

Made it home fine.  And it was fine for two years after that.

I pulled the codes after the incident, it was an EGR valve issue, but apparently the software can only detect if the EGR valve is faulty by looking at how the pressure changes when you go into low load.  I think it was just a combination of conditions (high humidity and rain, low temperature?) combined with probably a sticky or briefly intermittent sensor all combining together to cause a fault condition and on that car, most engine faults lead to limp home mode being activated.  There was no real reason to limit power, the fault would not kill the engine (at worst it would make the emissions a bit worse), but the software dictated the power must be low.

I don't think I've ever had a car that's been 100% solid, even my most expensive cars.  I've really gotten used to examining the VCDS fault logs for my current vehicle.  They are complex machines and there is lots to go wrong.

GLouie:
Many of those vague warning lights can take a while to reset after correcting the problem. I once had a loose gas cap light on a 2007 Civic, and it took a few days to turn off after checking the cap. Annoying, but documented in the manual.

I have heard that some modern OBDII faults can reset after so many start cycles, or it could be miles. May depend on the fault.

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod