Please explain OBDII levels

imactj2004

imactj2004

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Im losin it with Smog check codes.

Went to smog check station, failed with codes P0441 and P1281.

Took vehicle home, replaced purge flow valve, connected my scanner, and both codes went away. Scanner showed no codes stored.

Went back to Smog check and the guy connects his scanner and says that it’ll fail because I had a pending code of P0456 (small evap leak). Went home, came to this forum, and got lots of wisdom about what conditions are required for the vehicle to do its complete evap check test (driving conditions, fuel tank level). I then monitored those setting and was able to clear the pending 456 code with my scanner. Decided to drive for another 50 miles “just in case” and no code showed up.

Started the jeep this morning, checked scanner, and no codes stored or pending.

Went to Smog check, guy connected his scanner, and he says that I have “EVA” and “HTR” that arent set. I asked him what he was referring to so he showed me his scanner. Sure enough, those checks were failing on his scanner. I had him connect my scanner and he then pointed out that the IM monitor status for EVA and HTR were flashing (see video 4948.mov). I am not 100% certain, but I told him that those alerts were NOT flashing ten minutes ago before I left my house. He said “maybe something is wrong with your computer. I can run the test but its gonna fail.”

So then, I pull out of the Smog check bay and pull over to the side of the lot to check my scanner tool again myself. This time I get the same flashing alerts, plus two new ones: “CAT” and “02S”. ( See second video 4949.mov.)

Can anyone enlighten me on wtf is goin on? Kills me that the scanner doesnt have any actual codes and yet the smog check station says that I’ll fail simply because these are flashing. Do I have a computer problem or do I actually need to investigate all four of these alerts? And why would there be no alerts, then two, and then four in the course of three consecutive engine starts?
 

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First, just to be clear all of your monitors are showing as READY on your scanner?

If not, you can do the complete Chrysler drive cycle due ask monitors in your driveway with the rear axle on jack stands.
 
L J said:
First, just to be clear all of your monitors are showing as READY on your scanner?

If not, you can do the complete Chrysler drive cycle due ask monitors in your driveway with the rear axle on jack stands.
Click to expand...

This, look up Chrysler drive cycle. I hit a back road with a wide side of the road. It’s simulating traffic from whagbincan tell. Literally, hit 45 for a minute, then stop for 30 seconds, go for 2 minutes, stop, repeat 8 times kind of thing.

Just clearing the CEL does not mean the emissions checks are all “set”. I’ve had this issue 2 TJs and a JK. They literally go a year without a CEL and bam, the month before it lights up, never fails
 
LONGJP2 said:
If your clearing codes, it takes a while for everything to 'set' and become ready.
Look up drive cycles.
Click to expand...

Yes, with ODBII, there are several tests that the PCM performs to ensure that the emissions systems and the evap systems are working properly. When you reset codes, it also resets those tests so that they need to be performed again. In the process, a flag is set that the smog guy (and anyone with a code reader) can see, showing that those tests have not been completed. The PCM looks for certain conditions from the data stream coming into it, and performs the tests under those conditions. This is the "drive cycle" being referred to. If you've reset the codes, you have to drive under the right conditions so that the PCM performs its tests and sets the flag for those as complete. At that point (no codes, and all tests showing complete), you will be able to pass the smog check.

LONGJP2 said:
Also, there's an exemption for some of those for a known factory issue.
Someone else might have the link.
Click to expand...

The only one I know of is detailed in TSB 25-005-13-A. I know of this one because it applies to my LJ, but it's only 2005-6 model years that are affected. Since you have a 2004, I don't think that applies.
 
In your video there are 2 circle flashing at the top. Those are your sensors, and if they’re flashing it means they aren’t ready. Once the drive cycle is completed, they’ll turn solid and you’ll be ready to get inspected (assuming they don’t throw a code once they go ready). The smog guy did a lousy job explaining the situation. The report I get has a list of all the systems and it will say ready/not ready and explain exactly why the inspection failed.

Some states (like Texas) allow 1 or 2 sensors to be non-ready depending on how old the car is. I’m sure CA doesn’t allow for those sorts of shenanigans.
 
Just to clarify, the circles at the top of the scanner display don't directly represent the status of any sensors. Those represent each of the tests that the PCM must perform satisfactorily to pass the smog test. If any of those tests result in a fail, then the PCM will trigger a trouble code describing the problem. The code could either be a pending code or a mature code. Pending codes are set for continuously-monitored tests (like engine misses) and some other tests that aren't continuously monitored, but are repeated several times before being considered complete. If the PCM fails enough tests, the pending code will be promoted to a mature code. If the PCM passes enough repeated tests after the pending code is set, the pending code is deleted. Because pending codes are kind of a "maybe there's a problem" situation, they won't trigger the check engine light, but mature ones will. Confused, yet? Modern PCMs are pretty sophisticated, but with each degree of complexity comes an even bigger degree of frustration for techs!
 
imactj2004 said:
Im losin it with Smog check codes.

Went to smog check station, failed with codes P0441 and P1281.

Took vehicle home, replaced purge flow valve, connected my scanner, and both codes went away. Scanner showed no codes stored.

Went back to Smog check and the guy connects his scanner and says that it’ll fail because I had a pending code of P0456 (small evap leak). Went home, came to this forum, and got lots of wisdom about what conditions are required for the vehicle to do its complete evap check test (driving conditions, fuel tank level). I then monitored those setting and was able to clear the pending 456 code with my scanner. Decided to drive for another 50 miles “just in case” and no code showed up.

Started the jeep this morning, checked scanner, and no codes stored or pending.

Went to Smog check, guy connected his scanner, and he says that I have “EVA” and “HTR” that arent set. I asked him what he was referring to so he showed me his scanner. Sure enough, those checks were failing on his scanner. I had him connect my scanner and he then pointed out that the IM monitor status for EVA and HTR were flashing (see video 4948.mov). I am not 100% certain, but I told him that those alerts were NOT flashing ten minutes ago before I left my house. He said “maybe something is wrong with your computer. I can run the test but its gonna fail.”

So then, I pull out of the Smog check bay and pull over to the side of the lot to check my scanner tool again myself. This time I get the same flashing alerts, plus two new ones: “CAT” and “02S”. ( See second video 4949.mov.)

Can anyone enlighten me on wtf is goin on? Kills me that the scanner doesnt have any actual codes and yet the smog check station says that I’ll fail simply because these are flashing. Do I have a computer problem or do I actually need to investigate all four of these alerts? And why would there be no alerts, then two, and then four in the course of three consecutive engine starts?
Click to expand...

I can give you an overview of what’s going on so you can get a better understanding. I was a Ford master mechanic for years. Manufacturers switch to OBD2 when the government mandated that if a vehicle will produce more than 150% of emissions it must set a check engine light. To do this the manufacturers had to start monitoring systems in addition to sensors. What you see on the scanner are the system monitors ie; O2s ( oxygen sensors) evap (monitoring evaporative emissions from fuel system) HTR (oxygen sensor heaters) when you clear the codes you also reset the monitors and will have to do a drive cycle to clear or ready them. Your smog requirements will say how many must be cleared to pass smog. California it is all or all but one. This is how California can just scan the vehicle to pass smog because the computer is checking the emissions while driving. Those are the monitors you are seeing that have cleared or not cleared on the scanner. Obd2 also will have pending codes were the computer will see a fault and set a pending code but not a light until it see the fault again during another drive cycle or warm up cycle and will clear the fault if it does not repeat within so many drive cycles.
To clear these monitors you will need to perform a OBD2 drive cycle look this procedure up it will give you parameters to drive under certain conditions to get the monitors to clear, but you will have to fix any fault codes to perform this procedure. While you are doing this drive cycle the computer will run tests behind the scenes without you knowing to test the emission systems. You should be able to monitor the scanner to see them clear. Hope this helps clear some of the mysteries.
 
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hear said:
Some states (like Texas) allow 1 or 2 sensors to be non-ready depending on how old the car is. I’m sure CA doesn’t allow for those sorts of shenanigans.
Click to expand...

I wouldn't call Texas allowing non-ready sensors on old cars shenanigans def- secret or dishonest activity or maneuvering.

I believe CA is the supplier of all shenanigans related to vehicles in general and getting all of them off the road ASAP.
 
JEEPCJTJ said:
I wouldn't call Texas allowing non-ready sensors on old cars shenanigans def- secret or dishonest activity or maneuvering.

I believe CA is the supplier of all shenanigans related to vehicles in general and getting all of them off the road ASAP.
Click to expand...

Proof that neglecting the /s will always bite you. My bad.
 
Thanks everyone. All this makes sense, except:

- why would the scanner show 2 flashing ovals at one point and then 4 flashing ovals on next startup?
- I've been trying to complete all of of the drive cycle conditions but EVA and HTR are still flashing
 
imactj2004 said:
Thanks everyone. All this makes sense, except:

- why would the scanner show 2 flashing ovals at one point and then 4 flashing ovals on next startup?
- I've been trying to complete all of of the drive cycle conditions but EVA and HTR are still flashing
Click to expand...

did you clear codes or disconnect the battery along the way?
 
Those are the two longest ones to set because they have the most specific conditions required. Heated O2 sensors require a cold start and long idle (at minimum 12 seconds, longer is better) so that the computer can watch the O2 sensor voltage get to a normal range in the expected timeframe for an O2 sensor with a working heater.

The evaporative system usually takes at least two cold starts separated by a long enough period of time to have a full warmup cycle between, and also the fuel tank within a specific range.
 
hear said:
Proof that neglecting the /s will always bite you. My bad.
Click to expand...

California for a long time allowed 2 monitors to not be cleared then it went to one. Now I think it is none. Many early OBD 2 vehicles the tests can be hard to clear. The evap monitor can be very hard to clear sometimes never clearing in normal driving.
 
imactj2004 said:
Im losin it with Smog check codes.

Went to smog check station, failed with codes P0441 and P1281.

Took vehicle home, replaced purge flow valve, connected my scanner, and both codes went away. Scanner showed no codes stored.

Went back to Smog check and the guy connects his scanner and says that it’ll fail because I had a pending code of P0456 (small evap leak). Went home, came to this forum, and got lots of wisdom about what conditions are required for the vehicle to do its complete evap check test (driving conditions, fuel tank level). I then monitored those setting and was able to clear the pending 456 code with my scanner. Decided to drive for another 50 miles “just in case” and no code showed up.

Started the jeep this morning, checked scanner, and no codes stored or pending.

Went to Smog check, guy connected his scanner, and he says that I have “EVA” and “HTR” that arent set. I asked him what he was referring to so he showed me his scanner. Sure enough, those checks were failing on his scanner. I had him connect my scanner and he then pointed out that the IM monitor status for EVA and HTR were flashing (see video 4948.mov). I am not 100% certain, but I told him that those alerts were NOT flashing ten minutes ago before I left my house. He said “maybe something is wrong with your computer. I can run the test but its gonna fail.”

So then, I pull out of the Smog check bay and pull over to the side of the lot to check my scanner tool again myself. This time I get the same flashing alerts, plus two new ones: “CAT” and “02S”. ( See second video 4949.mov.)

Can anyone enlighten me on wtf is goin on? Kills me that the scanner doesnt have any actual codes and yet the smog check station says that I’ll fail simply because these are flashing. Do I have a computer problem or do I actually need to investigate all four of these alerts? And why would there be no alerts, then two, and then four in the course of three consecutive engine starts?
Click to expand...

On your evap monitor make sure tank is between 1/3& 3/4 full of full warm up vehicle with some city driving then road test steady speed around 50 mph for abut 3-5 minutes. It should run the evap test. You should be able to monitor the scanner while driving and see when it passes.
 
NskLJ said:
California for a long time allowed 2 monitors to not be cleared then it went to one. Now I think it is none. Many early OBD 2 vehicles the tests can be hard to clear. The evap monitor can be very hard to clear sometimes never clearing in normal driving.
Click to expand...

It depends on the year of the vehicle, precisely because so many early OBD2 implementations were garbage at best and in some cases full on defective. CA allows any single monitor as incomplete on 96-99. They still allow evap to be incomplete on anything 2000 and newer.

Also, while I don't live there, this is why I dislike the hate that California gets for their emissions. Are they strict? Yes. Have they made a hugely measurable difference in air quality there? Also yes. They're also a completely open book. Scroll through that page - that's well over a hundred different vehicles where they've specifically flagged repeat issues. Even includes allowing 2005-06 TJs to pass with the HO2 monitor to be incomplete because of the defective factory wiring.

Good luck getting that kind of info out of other states like AZ.
 
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IOwnCalculus said:
It depends on the year of the vehicle, precisely because so many early OBD2 implementations were garbage at best and in some cases full on defective. CA allows any single monitor as incomplete on 96-99. They still allow evap to be incomplete on anything 2000 and newer.

Also, while I don't live there, this is why I dislike the hate that California gets for their emissions. Are they strict? Yes. Have they made a hugely measurable difference in air quality there? Also yes. They're also a completely open book. Scroll through that page - that's well over a hundred different vehicles where they've specifically flagged repeat issues. Even includes allowing 2005-06 TJs to pass with the HO2 monitor to be incomplete because of the defective factory wiring.

Good luck getting that kind of info out of other states like AZ.
Click to expand...

Yes California has made a huge difference in air quality through the years. I know there are many exemptions for vehicle problems. I help a buddy with early bronco fuel injection conversions and any time it is a 76 we make it smog legal. I do not keep up on the regulations as he handles all the smog certification and the referees. I just modify harnesses and do troubleshooting, works out well for both of us. The one thin I don’t care for is Carb has almost become its own branch of government in California.
 
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Okay, so, I THINK this may be complicating things. On my scanner, I initiated an Evap leak test and now Im seeing in the scanner manual that I need to consult the service manual for instructions of how to STOP the test. I have a Haynes manual but that doesnt mention anything about system tests. anyone have any documented instructions?

06E09878-D4AC-40B9-B63D-FCB43C6AAC0C.jpeg
 
NskLJ said:
I can give you an overview of what’s going on so you can get a better understanding. I was a Ford master mechanic for years. Manufacturers switch to OBD2 when the government mandated that if a vehicle will produce more than 150% of emissions it must set a check engine light. To do this the manufacturers had to start monitoring systems in addition to sensors. What you see on the scanner are the system monitors ie; O2s ( oxygen sensors) evap (monitoring evaporative emissions from fuel system) HTR (oxygen sensor heaters) when you clear the codes you also reset the monitors and will have to do a drive cycle to clear or ready them. Your smog requirements will say how many must be cleared to pass smog. California it is all or all but one. This is how California can just scan the vehicle to pass smog because the computer is checking the emissions while driving. Those are the monitors you are seeing that have cleared or not cleared on the scanner. Obd2 also will have pending codes were the computer will see a fault and set a pending code but not a light until it see the fault again during another drive cycle or warm up cycle and will clear the fault if it does not repeat within so many drive cycles.
To clear these monitors you will need to perform a OBD2 drive cycle look this procedure up it will give you parameters to drive under certain conditions to get the monitors to clear, but you will have to fix any fault codes to perform this procedure. While you are doing this drive cycle the computer will run tests behind the scenes without you knowing to test the emission systems. You should be able to monitor the scanner to see them clear. Hope this helps clear some of the mysteries.
Click to expand...
my 06 4.0L won’t clear the say the tests are ready after I have done a number of drive cycles. P0153 finally showed up on my Innova scan tool. The EVA which I think is evap now shows as ready. I happened upon a TSB that addresses the CAT, O2S and HTR lights that are lit red. Apparently Jeep will rewire some wires under the main fuse panel by the battery. I called Chrysler and pointed out the TSB to him and he said I should take it by my nearest Jeep dealer for a fix. I already have the bank 2/sensor 1 02 sensor coming from Amazon NTK #23160. I’ll put that in and reset codes
 
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