Hello to all of you awesome Jeep owners.

I've always bought and sold cars within a few months because I get so bored of them; but man; I can't see myself selling my 2000 TJ!!!! WOOT!!!!! Love this thing.

Question: The car is running great and I just started using full synthetic oil.
The check engine light is NOT ON and everything is perfect.

I, however, went to two smog check stations and the computer says my Jeep has two error codes or errors so I can't complete the smog check.

He said they are soft codes so as not to turn on the check engine light.

I'm a little scared but want to get this darn thing fixed so I could register my car already.

Any suggestions on how I can do this (Please, I'm trying to save money right now and am PETRIFIED of visiting a Jeep dealer.

TY all advance. Jerry Brunford, you once wrote that Auto Zone can decipher my Jeep's codes for me. Will they plug up their own diagnostic tools or do I need to buy one? TY IN ADVANCE ALL!!!!!!

was it just the computer or what? did they connect anything to the exhaust?

Perhaps an old code that was never cleared? disco the battery for few minutes to reset the memory.

Though Autozone will read your codes for free without making you buy a reader, you should be able to read them on your own since you have a 2000 model TJ. The diagnostic codes can be read in pretty much any TJ except for the '98/99 model years. Just turn the ignition key on-off-on (not to Start) three times within five seconds and then leave it in the On position. Within a few seconds, have patience, any stored codes should start appearing in your odometer.

On not passing the smog test, two minor issues that commonly prevent it from passing would be the engine isn't thoroughly hot or aa leaky gas cap (could just not be screwed down tightly enough). The engine absolutely must be fully up to temperature (make sure the correct 195 degree thermostat is installed) before the test starts. The engine being a llittle on the hot side can help a lot where passing a smog test is concerned.

I think it was just the computer because they never connected anything to the exhaust.

I suggested dc'ing the battery but the two places said I'd have to drive for 50 or more miles to try it and then it might not work.

Hmm. are they b'sing me? All sensors should work because the check engine light isn't coming one.

Thanks Tripple88a.

i'm just curious, if you fail once, how many more times can you test (i've had to test 1 vehicle and i passed so no experience with fails... pretty much i buy a car, i get the test notices and i sell it a month after (still havent received anything about my jeep). I say disco the battery for like 15-20 minutes to clear everything, drive for half tank or so and then go to them again whenever you get the 50 miles. I've heard you need to drive xx miles too and i dont know if its true or not since i dont think they can check how long the ecu has been running for, i could be wrong though.

i have a 00 and turning the key on 3 times didnt work when i got a cel.

Okay; awesome advice. The two smog stations, however, just plugged the cable in and two errors appeared. I live 5 minutes away from this place so do you think the engine wasn't hot enought to get tested? If the gas cap isn't on, would that spring a code or just prevent it from passing.

I never really got it tested. The test couldn't start because of the two fail codes. Thanks again.

Triple88a, do you think dc'ing the batt will help? Thanks man.

If you're only 5 minutes from the smog test station, odds are the engine was nowhere near hot enough to pass a smog test. Though I'm not sure if that would also prevent it from passing the initial test before the probe is inserted into the exhaust. Disco'ing the battery before going in won't help as the smog test machine will "notice" that some codes that need a certain number of miles on them aren't properly set. This prevents people from just disconnecting the battery minutes before any smog test to clear any problem codes.

Get the engine good and hot (as hot as you can) and make sure the gas cap is on securely and that you don't ever fill the gas tank with the engine running which will also set a code that will prevent it from passing the smog test.

hedonist where are you in so cal. Ill be doing the smog thing this weekend myself and i have a scanner. Im in fullerton

Good point. Thanks. If I get it good and hot, will that prevent any bad codes from going on?

Thanks for the offer man. I'm in the San Fernando Valley. O, the joys of living in Cali. I guess if it makes are air cleaner for us and our children, it's worth it.

oh yea a little far hahaha. form what my enigne builder has told me he says that smog is 90 percent engine oil. he said change it right before you take it in and make sure the motor is at running temp when you go in. once you have your engine codes worked out im sure you will pass no prob

they didnt tell you what the codes are??? i would just take it to autozone and get it checked for free. let us know what the codes are. i have the full FSM at home

Not necessarily. The only guarantee is that it won't pass the main (when it's being driven on the rollers) smog test if the engine isn't hot enough.

lol, smog is mainly unburned fuel out the tail pipe (symptom of cold engine)

they dont do the rollers any more here in Illinois, they dont even test obd 1 vehicles any more.. lazy bastards.

Loose gas cap will usually throw a code for evap system leak.

Resetting the ecu will simply remove stored codes so let say you had a problem 2 months ago that you fixed, discoing the battery should clear that right up.

The PCV (positive crank ventilation) system of your vehicle is designed to allow your engine to breath fumes located in oil compartments (oil pan, ect.). The fumes are then burned through the combustion process. If the oil in your engine is contaminated due to inadequate oil changes it may very well cause your vehicle to fail the inspection. Contaminated oils are high in Hydrocarbons (HC) and will present a rich mixture to the engine chambers. Avoiding oil changes not only causes pre-mature engine wear but can also cause your vehicle to fail the smog inspection. Change your vehicle's engine oil before going to a smog station.
theres more going on then you think

i see what you mean my apologies there.

You said it in a nutshell.

^
You guys beyond rock.

Thanks to your comments guys (+10000000 to you guys!!!), I am inferring that it's the ECU storing old codes. I recall that the previous owner took it in and the mechanic forgot to install a sensor hence the check engine light went on. The guy I bought it from took it back and the guy installed the sensor and hence, the check engine light turned off.

My theory: The ECU was never reset and thus, the old codes are stored even though the Check Engine light is not on. So, I reset the ECU and I will drive for over 50 miles before I take it in again. I hope it works this time.

If it works, I owe you guys a Newcastle if we are ever on a trail ride together or if ever you guys are in Los Angeles.

You guys have literally saved me a lot of money and hearache. Even though this may not work, it's pretty exciting figuring out what could be wrong.

I passed with flying colors. my jeep was very clean. Co2 was at 14.8

my O2 was at 0.3

HCs were 0 and the average is 13 to 17 and max is 170

CO was 0.0 with a max of 1.0

i changed the oil right before i left and made sure i was at 210 degrees when i rolled up.

Agree 100%. I had a 91 camaro that I took to a smog only station, they had it sit for a hr. didn't pass smog and was labeled a gross polluter. Got the 2 year excemption. Went to smog a different smog only station and it passed. I didn't do any work to it during those 2 years. The smog station said the previous station ran it cold to make it fail.

*******CONGRATS RAWKIN!!!!!!!!!!!!!!!""""***********

In California, passing smog is a big deal!!!! Woot!!!

UPDATE:

ARGH!!!!!!!!!

Reset the ECU, drove for over 50 miles, got the cat nice and hot.

FRUCK!!! THe computer showed one error now instead of two and three things were red (o2 sensor, 2 something). I have no check engines lights on. The guys said I need to drive it more for everything to turn green.

O yea. My last guess: The one error is from the fuel cap? Will that throw an error code?

Darn it. If the check engine light does not turn on, can I still check for any error codes?

Thanks in advance. My Jeep was from Canada. Is it made slightly differently from US Jeeps?

O yea. I am going to try one more time so Jeep Gurus, please chime in.

I think I can find someone who can 'do it' for $300.

O well.

Yes definitely the OBD system checks the fuel tank for any air leaks so if the gas cap is loose or leaks air, it will set an emissions leak (like a gas cap) code. Plus it will set that same code if you ever fill up your gas tank with the engine running.

^
Should I buy a new gas cap to trouble shoot?

Do I need to reset the ECU again?

Thanks Jerry!!

PS: By the way, how can these ECUs be so finicky and sensitive as to sense an air leak from the gas tank?

By the way, Do you think I'd be wasting money by buying a new gas cap? Does OEM matter with gas caps?

Move to KY we don't have testing anymore.... the court system shut it down as I recall. Let us know when you pass.

Hedonist, did they ask you to take your cap off? When i tested my last car, they asked me to unscrew my gas cap and they tested it on their tester.

I just got my emissions notice today and will be testing monday

^
no they didn't. We never got that far.

They plugged it into the ECU and blam, one error code. So, I bought a gas cap today. I'm hoping it will remove the one error.

You think it will work triple88a?

Well for me they tested my gas cap first. What code did you say you were getting? I would reset the ecu because god knows how long it will take for the evap code to clear, drive a week and then give it a shot.

Before you flash the ECU I would suggest you go to the store (autozone or whatever) and ask to see what the stored code is.

^
Is it harmful to the Jeep to reset(FLASH) the ECU?

You know what, I reset the ECU and drove for two days only accruing 50 miles.

Do I need to drive for over 50 miles to get all systems to function correctly and the ECU to prevent throwing codes?

Thanks again.

I don't know the exact number of miles but yes, you have to drive it a minimum number of miles/starts before all its codes will be set properly so it can pass a smog test. I'd guess it probably takes more than 50 miles.

Resetting the computer doesn't hurt anything but sometimes it will run a little rough for a while while the computer re-learns all its parameters. For purposes of clearing stored codes that cause a check engine light, just disconnect the battery's negative (black) lead for 2 minutes and reconnect it.

By the way, to "flash" a computer means to load in a new revision of software/firmwear. That's something only the dealer can do for you.

I just took my rig in, in and out in 2 minutes and an obvious pass