Hi

I just got SMOG checked on my Sonata V6 2001 and failed due to high NOx(reading-836 where average is around 18). I have 72K miles on the car and it just runs fine with no issues at all.

The manual & TSB says high NOx is due to the EGR malfunction, but I am not sure if the 2001 Sonata V6 has the EGR ?

Can someone pl tell me
1) if there an EGR in the car?
2) If yes, where is it?
3) If no, then what should I do to repair it and pass the smog.

Thanks
-p

Yes it does have egr, almost every car sold in America within the last 20+ years has egr. Where it is I'm not 100% sure on a 2001 as I own a 2002. Have the codes scanned, run some high octane fuel from a Top Tier gas station like Shell, and add some Lucas Oil fuel additive. I suggest Lucas Oil and B.G. as they are the only two additives that I have seen really work in all my years of repairing and modifying cars. Lucas is easier to find though. I'll research your egr location and try to get back to you soon.

This post has been edited by Executive Sonata: Aug 17 2008, 08:38 PM

Thanks for the reply. If every car has an EGR then why does the Car Manual Says - "EGR (if installed)"?

I will wait for the location if u can please find it.

Thanks again.
-p

Remember, these cars were sold all over the world and come from Korea. Which means that some places don't require EGR. There should be a tube running from the rear header into the intake, that is the egr tube and the rest of the system is in the intake if I recall correctly.

You are right, almost all vehicles sold in America have EGR, but you are wrong in assuming all vehicles have an EGR system, with EGR valves, solenoids & associated plumbing. Only a few of the Hyundai engines have an EGR system. The rest of them have EGR effect, which is accomplished by intake/exhaust valve overlap, without a system involving an egr valve, solenoid, plumbing etc. In 2001, the only USA Hyundai engines that had an EGR system were the 2.4L (4 cyl) & the 3.0L V6 (XG). Try to find an EGR valve on your 2002 V6. Hope this helps

Yes, there is no EGR valve in the 2001 V6 Sonata. It does has an EGR effect which is obtained by the component called Purge Valve (at least the dealer told me that). I checked, the purge valve is working fine.

Next, I changed the spark plugs and they were all burned out, specially the rear ones. I hope this will solve the high NOX issue. Comments?

The Purge valve deals with burning hydrocarbons from the fuel system (gas tank/fueling system) and so forth, it does not deal with oxides of nitrogen (NOX) that is produced from an engine combustion chamber that is operating too hot! The dealer misled you!

thanks, so can u tell me why is it operating "too hot", what should I fix to get it pass.
i changed the spark plugs recently, changed the oil, checked the timing, checked th hoses.

thanks

Sorry, not without testing it myself. Sometimes a car will have extreme carbon build-up including on top of the pistons. This will increase combustion temps. A Fuel & emission system flush and cleaning may remedy this.

is this something which I can do myself? can you point me to something which has more details of how "Fuel & emission system flush" can be done.

thanks much
-p

got a pre-test smog test done today...failed again due to the same reason - high NOX.

Can someone please tell me how to do "Fuel & emission system flush"?

Thanks

Will seafoaming help? Anybody done seafoaming on sonata v6 ?

thanks

Just want to add my story.
The same car, emission failed-high NOx.
First time - reading around 800 ppm, CO and CH OK.
Catalytic changed, second test-failed, same readings.
Catalytic replaced back, O2 sensor changed(front, radiator side, after getting code P0153-slow response), test- failed, NOx about 1200 ppm.
replaced second front O2 sensor and computer reprogrammed at dealership,
pretest- NOx around 2000.
Catalytic changed again, test - failed, NOx - 900.
Suggestions?

Man this is scary, anyway, on my second test(failed) the nox went lower cause I used G2P, changed oil and changed the spark plugs.

I recently did seafoam the car too and am planning to take it to a mechanic for diagnostic. I was thinking to change the oxygen sensors but dont really knwo which one is bad...and dont know how to re-program the ECM. Do u think a local mechanic will be able to re-program the ECM? cause the dealer charges $250 just for the diagnostic and without that they won't touch the car.

I hope u have already checked ur hoses for the leaks.

All the hoses checked, throttle body cleaned, new oil and filters, spark plugs and wires about 1 year old(checked-looks OK), car is running good, never had a problem and never had "check engine" on.After all replacements can't see the difference.
I doubt that local mechanic can reprogram ECU, at least mine can't.I did it at dealership, as well as diagnostic. BTW, I was charged around $100 for diagnostic and the same amount for reprogramming.
Anyway, it didn't help.Yet.
Now I'm waiting for OBD scanner(bought on e-bay) and then I will check by myself the codes and other parameters.
What is seafoam?

Search for seafoam on youtube. its a quick/cheap way to get rid of carbon deposits in the engine. The videos even tell how to do it.

How many miles do u have on ur car? What is the timing on ur car?

Can we increase the tiiming on the car and see the results? cause they say u see high nox cause the car is running lean or the engine has high carbon deposits.

We have exactly same issue (hign nox) and need to communicate pretty often. Can you email me at pa_arora@yahoo.com so that I have ur email id.

This post has been edited by pa_arora: Sep 5 2008, 06:36 PM

Mailed.
130000 km on body, unknown on engine.
Looks like only us with this ******* problem with NOx?

Allright guys, finally passed the SMOG today.

Gave the car to a local mechanic today for diagnostic and repair. He said B2S1 oxygen sensor is bad and got it replaced. Passed the smog and the NOX was under the max limit.

Vik, you may also try changing the O2 sensor. Hopefully it will pass too.

Good luck and thanks

-p

Idk about your sensor issue but seafoam will help remove carbon deposits. I personally put it directly into the intake cause its most effective that way.

Putting it in the tank can accomplish the same results or so i hear but if that were the issue, seafoam is the way to go.