# Can't pass smog **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** sensors\ **Created:** [August 13, 2014, 9:31am UTC](https://community.cartalk.com/t/cant-pass-smog/86574 "2014-08-13T09:31:40Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![Hyundainightmare](https://avatars.discourse-cdn.com/v4/letter/h/ecc23a/32.png) [@Hyundainightmare](https://community.cartalk.com/u/Hyundainightmare)\ **Post date:** [August 13, 2014, 9:31am UTC](https://community.cartalk.com/t/cant-pass-smog/86574/1 "2014-08-13T09:31:40Z")
I own a 2005 Hyundai Sonata. I am unable to pass smog in California because of the OBD system isn’t ready. Mechanics simply tell me to drive it and I looked up the drive cycles for the car and tried to follow them as best I could but it still won’t pass. I’ve gone to a smog referee and the DMV to file for an extension (which is now over) and I still can’t pass smog. Every mechanic, including the dealership, don’t know what’s wrong with the car and won’t even attempt to repair it because it is such a general error. The techs on the smog hotline told me it is the O2 sensor and the catalytic sensor but when I tell this to the mechanics they still won’t repair it because they don’t know what to fix because there are so many sensors. What do I do? ---
**Author:** ![pleasedodgevan2](https://avatars.discourse-cdn.com/v4/letter/p/ad7895/32.png) [@pleasedodgevan2](https://community.cartalk.com/u/pleasedodgevan2)\ **Post date:** [August 13, 2014, 10:29am UTC](https://community.cartalk.com/t/cant-pass-smog/86574/2 "2014-08-13T10:29:11Z")
A lot of talking without specifics is happening here. I wonder why nobody can test anything but they can stay smog certified. Leave a comment with the codes if you know them. Somebody knows how to test things so your mission, should you accept it, is to find that person. The secretary will disallow all knowledge… ---
**Author:** ![BustedKnuckles](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bustedknuckles/32/25_2.png) [@BustedKnuckles](https://community.cartalk.com/u/BustedKnuckles)\ **Post date:** [August 13, 2014, 1:55pm UTC](https://community.cartalk.com/t/cant-pass-smog/86574/3 "2014-08-13T13:55:05Z")
Is the Check Engine light on? Or is it simply not ‘emissions-ready’? The monitors for the evap system and cat system need to collect data from different driving conditions before they are ‘emissions-ready’. Drive cycle instructions usually will get the correct data in the system in the shortest amount of time, usually within the drive cycle. Normal driving usually gets the correct data within a few days. If the monitors are still not ‘emissions-ready’ within a week, there is a problem. First thing to do is check all the fuses. The ECM needs keep-alive memory in order to maintain the data for the readiness monitors. If the fuse is blown, it continually resets itself. ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [August 13, 2014, 4:45pm UTC](https://community.cartalk.com/t/cant-pass-smog/86574/4 "2014-08-13T16:45:27Z")
You need to find a real mechanic who specializes in this type of work… Knuckles pointed out one likely cause, the “computer” (ECM) is losing voltage when you turn the key off…A blown fuse is the likely cause… ---
**Author:** ![SteveC76](https://avatars.discourse-cdn.com/v4/letter/s/958977/32.png) [@SteveC76](https://community.cartalk.com/u/SteveC76)\ **Post date:** [August 13, 2014, 5:17pm UTC](https://community.cartalk.com/t/cant-pass-smog/86574/5 "2014-08-13T17:17:38Z")
Do you know if its only the oxygen sensor and catalyst monitors not setting or all monitors unset? If it is just the 2 the ecm memory is good. If it is just O2 and cat I would find a shop that has a Pico scope and have them watch the waveforms for all the O2 sensors. It sounds like you have one that is going bad, just not bad enouh to set a code. I will try to see if there are any know issues with these at work today. Steve ---
**Author:** ![keith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/keith/32/5518_2.png) [@keith](https://community.cartalk.com/u/keith)\ **Post date:** [August 13, 2014, 11:41pm UTC](https://community.cartalk.com/t/cant-pass-smog/86574/6 "2014-08-13T23:41:34Z")
I would think that those mechanics would be or should be awfully embarrassed if Caddyman is right and its only a fuse. I would be. ---
**Author:** ![SteveC76](https://avatars.discourse-cdn.com/v4/letter/s/958977/32.png) [@SteveC76](https://community.cartalk.com/u/SteveC76)\ **Post date:** [August 14, 2014, 8:43am UTC](https://community.cartalk.com/t/cant-pass-smog/86574/7 "2014-08-14T08:43:34Z")
Here is an older drive cycle [www.google.com/url?sa=t&source=web&cd=6&ved=0CDEQFjAF&url=http%3A%2F%2Fwww.obdclearinghouse.com%2Fdocuments%2Fnewdocuments%2Fhyundai%2Fsonata%2F0236030.pdf&rct=j&q=05%20hyundai%20will%20not%20run%20monitors&ei=XT3sU4usJY3soAT8uIKgBA&usg=AFQjCNE1jphdMEk0FblwHrFnBfj981Qg1w&sig2=csa1UoK3Vu7awQD5-jUqSA&bvm=bv.73231344,d.cGU](http://www.google.com/url?sa=t&source=web&cd=6&ved=0CDEQFjAF&url=http%3A%2F%2Fwww.obdclearinghouse.com%2Fdocuments%2Fnewdocuments%2Fhyundai%2Fsonata%2F0236030.pdf&rct=j&q=05%20hyundai%20will%20not%20run%20monitors&ei=XT3sU4usJY3soAT8uIKgBA&usg=AFQjCNE1jphdMEk0FblwHrFnBfj981Qg1w&sig2=csa1UoK3Vu7awQD5-jUqSA&bvm=bv.73231344,d.cGU) try it or contacting your local hyundai dealer to confirm it is accurate ---
**Author:** ![SteveC76](https://avatars.discourse-cdn.com/v4/letter/s/958977/32.png) [@SteveC76](https://community.cartalk.com/u/SteveC76)\ **Post date:** [August 14, 2014, 8:45am UTC](https://community.cartalk.com/t/cant-pass-smog/86574/8 "2014-08-14T08:45:11Z")
Sorry link did not copy [obdclearinghouse.com](http://obdclearinghouse.com) has the drive cycle to run monitors. ---
**Author:** ![wesw](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/wesw/32/2713_2.png) [@wesw](https://community.cartalk.com/u/wesw)\ **Post date:** [August 14, 2014, 3:51pm UTC](https://community.cartalk.com/t/cant-pass-smog/86574/9 "2014-08-14T15:51:46Z")
you know, I ve never had a mechanic tell me he would not repair my problem without telling me about someone who would, yet it seems to be a fairly common complaint here. do you pros often refuse to work on otherwise safe cars without recommending someone else? ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [August 14, 2014, 4:29pm UTC](https://community.cartalk.com/t/cant-pass-smog/86574/10 "2014-08-14T16:29:27Z")
There is probably more to this story…In CA, everybody passes the smog test one way or another…This may be a money issue more than a mechanics will or skill… ---
**Author:** ![wesw](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/wesw/32/2713_2.png) [@wesw](https://community.cartalk.com/u/wesw)\ **Post date:** [August 14, 2014, 5:08pm UTC](https://community.cartalk.com/t/cant-pass-smog/86574/11 "2014-08-14T17:08:40Z")
yeah, I can see how that might be ---
**Author:** ![wesw](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/wesw/32/2713_2.png) [@wesw](https://community.cartalk.com/u/wesw)\ **Post date:** [August 14, 2014, 5:14pm UTC](https://community.cartalk.com/t/cant-pass-smog/86574/12 "2014-08-14T17:14:31Z")
if you go to a shop and tell them you want a couple of sensors changed, I can t see them saying no. they might tell you that they offer no guarantee of results, but if you have a specific request to change a part, why would they turn down easy money? the fuse thing seems a reasonable thing to check first. I always check the simplest or cheapest possible cause first as a rule. even if it is not the cause you lose little and possibly gain much ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [August 15, 2014, 2:40am UTC](https://community.cartalk.com/t/cant-pass-smog/86574/13 "2014-08-15T02:40:03Z")
As a matter of fact, plenty of people fail smog here in California There are plenty of smog techs who don’t want to risk their license, and the shop’s reputation, by breaking the rules As far as I know, the “authorities” send spies to smog shops to see if they’re on the level, taking shortcuts, taking bribes, etc. ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [August 15, 2014, 3:01am UTC](https://community.cartalk.com/t/cant-pass-smog/86574/14 "2014-08-15T03:01:06Z")
Anyone with a laptop and $30-$40 for a USB adapter cable and a diagnostic program can plug into the OBD-II port and monitor their cars engine performance and emissions related problems, codes, settings…If the ECM is “unready to test” then the reason for this can be quickly determined and the problem corrected…They have been doing this in California for 35 years or more…It was once considered rocket science but not any more… ---
**Author:** ![SteveC76](https://avatars.discourse-cdn.com/v4/letter/s/958977/32.png) [@SteveC76](https://community.cartalk.com/u/SteveC76)\ **Post date:** [August 15, 2014, 4:46am UTC](https://community.cartalk.com/t/cant-pass-smog/86574/15 "2014-08-15T04:46:40Z")
Running monitors is not always a simple task, certian drive patterns have to be followed for the monitors to run some of which are very difficult to duplicate. Any shop that simply replaces parts is looking for trouble. If the parts you install dont fix the problem you become the bad guy even though you only did what the customer asked. I have seen many shops deal with this nightmare. Its true there are shops that will cheat the smog checks, many get caught and the fines and the penalities are not worth it. My smog license provides me an advantage over many techs out there. I much rather fix cars than pay fines to the state.