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Discussion Starter #1
As the title says, my CEL goes on and flashes too.

I've read up a bit on why the CEL comes on/flash and it says it has something to do with the exhaust system and if continue operating will damage the catalyst converter (which I don't understand since I'm a car dummy :p)

In addition, the engine vibrates like crazy. I can feel the engine vibrating when I'm inside the car as well.

Any insights??

P.S. - I already got the car tolled to the dealership and they kinda just told me it might be misfirings and then they said they couldn't locate the problem. So my car basically has to stay there until they open again on Monday and hopefully they will figure out the problem/fix it under the warranty and call me back.

P.S.S. - The problem arised late Friday night and I just did a 30K maintanence on Thursday. (but the car already has 43,000 miles on it)
 

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When the check engine light comes, it means you need a code scan to determine what the problem is. I assume you're still under warranty, so take it to the dealer.
 

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The vibrating sounds like a miss. How bad is the miss? Car shakes bad at idle? When under throttle it runs great? A blinking cel is usually a lazy o2 sensor, which if the primary one (on the exhaust manifold) will cause some missing, and possibly some sluggishness. But lazy isnt the end of the o2 sensor, it still has some life, as the car probably runs fine sometimes hit or miss.

My guess would be the primary o2 sensor... How many miles are on the car? Around 60k or more? What I'd do is swap the rear o2 with the front o2 if ur tight on cash. Reset the ecu and see how it goes. But this is just a total hunch... I have no idea what the car has done to it, the miles, nor even a code read out. But my guesses are pretty solid. Scan it, and let me know, I'll go from there. o2 sensor is about 60 bucks, possibly more, and the time involved it about an hour depending on ur skills, and how stuck the o2 is.

EDIT:
Sorry I didn't fully read your post. It's plausible that it's the o2 around that mileage. Secondly, a misfire overtime will cause your cat to be screwed because of all the unburned fuel. :(. Also, your motor, when missing will be running insanely hot. Not necessary lean, but rich.
 

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Discussion Starter #4
Thanks for the input guys.

And yeah the car shakes really bad at idle. And how long of a misfire will it take to damage the cat? Do you mean if I continue driving it? or even leaving it at it's current state with the engine off with damage the cat too?

And as far as replacing it for $60, I can manage that... but I have no idea how to work on it so I'll probably have to leave it to the stealership to mug me legally. :( And since you say it has to do with the exhaust, then I assume it's not gonna be covered under the warranty? (I believe I read it in the warranty handbook that exhaust is not covered.. -__-)

P.S. - The car's from FL but I'm in NY at the moment. Where you located in NY?
 

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 Leaving the engine off in this state won't hurt a thing!  Running it may...  The catalytic converter can be damaged from the engine misfiring - not sure how long it would take to cause permanent damage, but I wouldn't drive it much like this. :grin:

Did you happen to replace your spark plugs as part of your 30,000 maintenance?  If you haven't done so and you're misfiring, that's something to check.
 

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WOW, a 2006+ Accent with an actual mis-fire.... every time we get them, they run smooth as can be, and have have all 3-5 mis-fire codes, so we just install the latest mis-fire logic program and send them down the road.

Flashing MIL means something bad enough that will kill the cat.... get it repaired NOW !!

Exhaust system is not a monitored part... just the contents into the manifold/catalyst and what come out of the cat.. everything beyond has no value.
 

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QUOTE (sbr711 @ Jun 20 2010, 01:31 PM) index.php?act=findpost&pid=334673
WOW, a 2006+ Accent with an actual mis-fire.... every time we get them, they run smooth as can be, and have have all 3-5 mis-fire codes, so we just install the latest mis-fire logic program and send them down the road.

Flashing MIL means something bad enough that will kill the cat.... get it repaired NOW !!

Exhaust system is not a monitored part... just the contents into the manifold/catalyst and what come out of the cat.. everything beyond has no value.
You have no knowledge of vehicles. Please don't post illegitimate things, with no known knowledge behind it. Flashing MIL dosen't mean that at all. There are very few codes that cause a flashing MIL... They can be vacuum related, exhaust related, or even intake related. Mass Air Flow Sensor, Map Sensors, TBI, leaks, exhaust leaks, etc, etc. All that can cause a flashing MIL. Flashing MIL means it's a pending code that comes and goes. The car knows somethings wrong, but sometimes in certain situations the car runs beautifully. The computer realizes this. So please, calm down. Dosen't mean it will kill the cat, however running it for a LONG period of time will damage the catalytic converter. The honey comb inside the cat that is used to extract harmful gases to the environment, is sensitive to gas. All the unburned fuel can harm it.

Secondly the exhaust system is heavily monitored... It tells SO much about the car. Lean, rich, how the cat is functioning, etc. They are by far the most important sensors on the car... Without them you know nothing about your vehicle. Could lean out, and detonate... How would you know? Ohhhh, your o2 sensor would tell you. Could be running retardedly rich... How would you know? Ohhhh, your o2 would tell you...
 

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Whatever anyone tells you here, trust that a FLASHING check engine light is serious. A flashing check engine light, means there is a 'class A' misfire that is present. Not a random/infrequent misfire. A constant misfire.

This type of misfire WILL ruin the catalytic converter if the problem isn't fixed in a timely manner.

It's been that way since OBD-II came out in 1996. All of the codes (should) mean the same thing across all makes. There ARE specific codes that only pertain to that manufacturer and some, just that model from the manufacturer. A code P0104 is trouble with the MAF circuit for instance. Same for all makes. A flashing MIL (check engine light) means a misfire is happening now.

A flashing MIL does NOT mean there's a pending code. It means there is a mis-fire. Nothing more, nothing less.
 

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this has happened to me on many occasions, once was when the car haddent been run for 5 weeks, the other was when i was revving it up while at a light. i just hammered on the gas till it went away, usually a few seconds. i found it haddened because the sparkplugs had a build up or in the case of it not being running, a wee bit of rust. it went away for me. and i didnt worry cuse i have a header back exhaust so it not a big deal to fix
 

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QUOTE (StevenWang @ Jun 20 2010, 06:01 PM) index.php?act=findpost&pid=334729
You have no knowledge of vehicles. Please don't post illegitimate things, with no known knowledge behind it.
Please refrain from attacking other members, that tone is not necessary.  FWIW, I've seen a lot of very helpful posts from sbr711 -  it's apparent that they work at a dealer and I haven't seen them post anything that was inaccurate.  We're fortunate to have our resident dealer techs around to help us out if you ask me!

If you check your owner's manual (image attached,) it states warnings about driving the car with a flashing check engine light.  Every OBD-II equipped car I've owned has had similar warnings in the owner's manual.  Hyundai's warning isn't as doom and gloom as I've seen with other makes, but still...

A flashing malfunction indicator does light indicates that a misfire is occurring now as was mentioned.  When the misfire goes away, my experience has been the light will then remain solid until the code is cleared.  I had a car with a bad fuel injector, every time I accelerated it began misfiring badly and the light would flash.  Let off the gas, the misfire went away and the light went back solid.
 

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QUOTE (StevenWang @ Jun 20 2010, 03:01 PM) index.php?act=findpost&pid=334729
You have no knowledge of vehicles. Please don't post illegitimate things, with no known knowledge behind it.
I've known sbr711 for quite some time now and trust me, he knows his stuff and is a VERY legitimate source of Hyundai tech info. So don't talk smack about somebody whom you know nothing about.
 

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QUOTE (nascarfan7 @ Jun 20 2010, 06:27 PM) index.php?act=findpost&pid=334735
Whatever anyone tells you here, trust that a FLASHING check engine light is serious. A flashing check engine light, means there is a 'class A' misfire that is present. Not a random/infrequent misfire. A constant misfire.

This type of misfire WILL ruin the catalytic converter if the problem isn't fixed in a timely manner.

It's been that way since OBD-II came out in 1996. All of the codes (should) mean the same thing across all makes. There ARE specific codes that only pertain to that manufacturer and some, just that model from the manufacturer. A code P0104 is trouble with the MAF circuit for instance. Same for all makes. A flashing MIL (check engine light) means a misfire is happening now.

A flashing MIL does NOT mean there's a pending code. It means there is a mis-fire. Nothing more, nothing less.
Sigh... Not in all cases. This case I most certainly guarantee it's the manifold o2.
 

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QUOTE (lovemysantafe @ Jun 20 2010, 11:23 PM) index.php?act=findpost&pid=334806
I've known sbr711 for quite some time now and trust me, he knows his stuff and is a VERY legitimate source of Hyundai tech info. So don't talk smack about somebody whom you know nothing about.
Clearly knows nothing. Read what he said... Exhaust is the MOST monitored section of any vehicle. It tells you what's wrong when it's not running certain parameters. And I highly doubt he's a Hyundai Tech... Well maybe he is. Hyundai offered me, well Prestige in Kingston (Toyota, Scion, Hyundai) 45k a year to be a tech. Sorry I don't wanna do oil changes all day.
 

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QUOTE (bloodninja @ Jun 21 2010, 12:09 AM) index.php?act=findpost&pid=334819
OK guys. Back on topic. We all know how off topics get closed. Lets keep legitimacy rollin. :)
+1.
All I'm saying is flashing isn't always related to one type of code. And he didn't get into detail about how it flashes, when it flashes. How long the CEL has been on, how many drive cycles. When it started, what the car was doing. There's so much info that I really can't diagnose it over the forum, however I believe it's related to the primary o2 (air to fuel ratio sensor).
 

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QUOTE (StevenWang @ Jun 20 2010, 11:33 PM) index.php?act=findpost&pid=334811
Clearly knows nothing. Read what he said... Exhaust is the MOST monitored section of any vehicle. It tells you what's wrong when it's not running certain parameters. And I highly doubt he's a Hyundai Tech... Well maybe he is. Hyundai offered me, well Prestige in Kingston (Toyota, Scion, Hyundai) 45k a year to be a tech. Sorry I don't wanna do oil changes all day.

Mr Wang.... RIF

Note post #6 is not edited. nor will it be edited, so slowly read, and understand..

What is your qualifications for OBD-II ? Can you use the item in the 2nd pic proficiently ?

Mine - (4) 2 & 3 day courses with Toyota Motor Co in Scan tool, Driveability, Advanced Emission
------> Scan tool and Emission with Nissan
------> Kia Motor Co, Hi-Scan, GDS, driveability, and Emissions
------> Hyundai Motor Co, Hi-Scan, Service Tools, Engine Managment 3
 

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QUOTE (hoosieraccent @ Jun 20 2010, 08:24 PM) index.php?act=findpost&pid=334755
Please refrain from attacking other members, that tone is not necessary.  FWIW, I've seen a lot of very helpful posts from sbr711 -  it's apparent that they work at a dealer and I haven't seen them post anything that was inaccurate.  We're fortunate to have our resident dealer techs around to help us out if you ask me!

Thank You kind Sir :banana:
 

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QUOTE (sbr711 @ Jun 21 2010, 07:45 PM) index.php?act=findpost&pid=335061
Mr Wang.... RIF

Note post #6 is not edited. nor will it be edited, so slowly read, and understand..

What is your qualifications for OBD-II ? Can you use the item in the 2nd pic proficiently ?

Mine - (4) 2 & 3 day courses with Toyota Motor Co in Scan tool, Driveability, Advanced Emission
------> Scan tool and Emission with Nissan
------> Kia Motor Co, Hi-Scan, GDS, driveability, and Emissions
------> Hyundai Motor Co, Hi-Scan, Service Tools, Engine Managment 3
Yeah we got a few tools, one of which being autoboss. X-431
and a few others. Let me give you an example of something.
P2096 is a post catalyst fuel trim system to lean right? That means you're running lean? Nope. Means a rich condition is present. More then likely it's an exhaust leak of the rear o2 sensor cause a rich condition. The engine is trying to compensate. Now, if you have a post catalyst fuel trim to rich (P2097) what's the issue? Are you running rich? Yep. But how do you trouble shoot that? Something is causing a rich condition and it needs to be addressed. Now, my point here, which might not be comprehendable is that these scan tools, only go so far. The boss we have is good to check sensors, and things like that, but again, only so far. Most people don't have the hands on knowledge that work at dealerships. Another example, my friend is a master honda tech, but he has no idea how to bore, sleeve, rebuild or anything engine related, crazy right? I built his whole Frankenstein from the ground up, and he pretty much just watched. Most people don't even know what deck height is... Anyway, I find it retarded that we're arguing about what the issue is here... Clearly there's a missfire, we've stated that, and that is factual. But what's causing the miss, we don't know... However my hunch of the air/fuel ratio sensor is a step toward the right direction. I've seen this before, several times infact... I'm 20 years old, and I have more hands on experience with hyundai's and kias then most people that work on them day in and day out at a dealership...
 
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