OBD system not ready. HELP!

DickGTS01 · May 21, 2009

Hi guys,

I just took my 2001 GTS for a state emission inspection. I flunked. The rejection message says "The On-Board Diagnostics system is not ready to make a determination regarding the condition of the pollution control system on this vehicle". Specifically, the tests for Catalyst and Evaporative System faiiled (I still have the catalysts on the car).

I replaced the battery a few weeks ago and haven't driven it much since then. Does the OBD require some length of drive time (or mileage) to make pollution determinations?

Does anyone have info on how the OBD works after a battery replacement??

Thanks,

Dick

Tagoo · May 21, 2009

I had the same problem with a dead battery right before and emissions inspection. You just have to drive the car a bit to get the computer to reset itself. I drove 30 miles or so and then went for a retest - all was fine.

Tom F&L GoR · May 21, 2009

It's not the total miles, it's the number of times it starts cold and warms up enough.

DickGTS01 · May 22, 2009

Thanks, guys.

I was hoping the problem was something like that. I'll drive it more then go for a re-test.

Dick

JeffTheViperMan · May 22, 2009

Tom said:
It's not the total miles, it's the number of times it starts cold and warms up enough.

Still not entirely true:

Each monitor of the OBD system has specific requirements that must be met before the PCM will perform the test. Some monitors require you to be moving but with no throttle (i.e. "coasting.") Some require certain coolant temps, some require certain RPM's. Some tests for the Evap monitors require a fuel level above 25% full but less than 75% full... It's all very nitpicky. Luckily, 2000"ish" models aren't nearly as strict as today's 2008/9 models. So as one poster said above, go drive it around for a half-hour or so. Make sure you cut the engine off at least once in that time-frame (some monitors have to run twice before the PCM will give it the "all-clear") and then try again.

Jeff
2005 Honors Graduate
Wyoming Technical Institute for Automotive Technology

Tom F&L GoR · May 22, 2009

I re-phrase to further define needed cycle:
I believe that early OBD-II's most basic test is catalytic activity, which looks at downstream O2 from cold conditions. So it has to see warming up activity as well as fully warmed up (upstream) O2 signal. Hence it should start, warm up, cool off enough to go through a "cold start", start, warm up before announcing readiness. I would not think one longer trip or a very short engine-off would do it. After two warming up cycles you would also "probably" have met all the other requirements.

Tom F&L GoR · May 22, 2009

Wow, Dick, that's a boatload of posts. There must be another really hoppin' forum I don't visit!

bluesrt · May 22, 2009

:

JeffTheViperMan said:
Still not entirely true:

Each monitor of the OBD system has specific requirements that must be met before the PCM will perform the test. Some monitors require you to be moving but with no throttle (i.e. "coasting.") Some require certain coolant temps, some require certain RPM's. Some tests for the Evap monitors require a fuel level above 25% full but less than 75% full... It's all very nitpicky. Luckily, 2000"ish" models aren't nearly as strict as today's 2008/9 models. So as one poster said above, go drive it around for a half-hour or so. Make sure you cut the engine off at least once in that time-frame (some monitors have to run twice before the PCM will give it the "all-clear") and then try again.

Jeff
2005 Honors Graduate
Wyoming Technical Institute for Automotive Technology

i agree

very correct statement

Ulysses · May 22, 2009

I think Dick has everyone beat in the highest number of posts category.

DickGTS01 · May 22, 2009

Well, I hope you figured out that the number of posts is in error. In fact, I haven't posted much at all in the two years since I retired. I used to chime in regularly on my lunch break, but not so much since I don't sit in front of a computer all day.

Maybe I'll write a "trouble ticket" on the forum ;-).

Thanks for all the info. I'll drive it for a few days then go for a re-test.

Have a nice week-end.

Dick

TAXIMAN1 · May 22, 2009

Also, check cig. lighter fuse.... If blown, the OBDII will not respond, as it pulls power from here... Had this happen on my 06' SRT.

Bandit3 · May 22, 2009

Dick, what state are you in? I own an emission station, in Georgia, and will do free retests until your ECM is ready. John

Ricketts · May 23, 2009

Yes, you have to do a drive cycle on it after disconnecting the battery, or clearing check engine light. Got another question for you, how in the work did you get this many posts? :rolaugh:

DickGTS01

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Join Date: Jul 2008
Posts: 4,294,967,295

dave6666 · May 23, 2009

I need to get some pointers from Dick. He seems to have the answer on post counts.

Tom F&L GoR · May 23, 2009

disconnecting the battery will restart the counts and still show not ready.

Wow, 13,000,000,000 posts per day. That's impressive, Dick.

Joseph Dell · May 23, 2009

I hate it when this happens. It sometimes takes WEEKS for the system to reset itself. Fortunately there are other ways to address this. PM sent!

JeffTheViperMan · May 26, 2009

TAXIMAN1 said:
Also, check cig. lighter fuse.... If blown, the OBDII will not respond, as it pulls power from here... Had this happen on my 06' SRT.

That only powers the port itself under the dash - it doesn't affect the performance of the PCM or the various monitors that it has to run.

You are correct in that it WILL cause a malfunction when trying to connect to the PCM to run diagnostics or emissions testing. However, it'll generally give a "Cannot Communicate to PCM" or "Check Connection to OBDII Port" on your scanning device. If he's being told the monitors aren't ready, he's already gotten past that point.

Tom, the catalytic efficiency monitors looks for variance between the upstream and downstream O2 sensors. The upstream O2's will fluctuate wildly in their signal pattern, whereas downstream O2's should generally remain constant, or show changes only over a longer period of time. Also note that some of the tests are performed very quickly. For example, the "O2 Sensor Heater Circuit Malfunction" code that haunts Gen II users with aftermarket exhausts (such as myself) actually trips within the first fifteen seconds of operation.

For final reference, the Dodge Service manuals for each respective Viper model year will give the specific details on what each monitor needs to run. Sometimes I wonder how someone came up with all this nonsense!

Tom F&L GoR · May 26, 2009

JeffTheViperMan said:
Tom, the catalytic efficiency monitors looks for variance between the upstream and downstream O2 sensors. The upstream O2's will fluctuate wildly in their signal pattern, whereas downstream O2's should generally remain constant, or show changes only over a longer period of time. Also note that some of the tests are performed very quickly. For example, the "O2 Sensor Heater Circuit Malfunction" code that haunts Gen II users with aftermarket exhausts (such as myself) actually trips within the first fifteen seconds of operation.

Yes, I am familiar with all this, believe me. At the big oil company we had to interpret all the diagnostics when we disassemble/reassemble engines, disconnect/reconnect sensors, change power supplies, try to run the PCM with or without the AC compressor, power steering pump, and other goofy things...

My original answer was not for what makes the CEL come on or how to run the diagnostics, but what it takes to get the system to show "ready" for a state inspection.

bluesrt · May 26, 2009

bottom line is,some cars that are hell to get to rediness result,get the computer re-flashed and it will then cooperate after driven-plain and simple-if , the instructions that are stated to follow sometimes still doesnt work- get it re-flashed,well money spent in alot of other ways for the car anyway-

TAXIMAN1 · May 26, 2009

JeffTheViperMan said:
That only powers the port itself under the dash - it doesn't affect the performance of the PCM or the various monitors that it has to run.

You are correct in that it WILL cause a malfunction when trying to connect to the PCM to run diagnostics or emissions testing. However, it'll generally give a "Cannot Communicate to PCM" or "Check Connection to OBDII Port" on your scanning device. If he's being told the monitors aren't ready, he's already gotten past that point.

Tom, the catalytic efficiency monitors looks for variance between the upstream and downstream O2 sensors. The upstream O2's will fluctuate wildly in their signal pattern, whereas downstream O2's should generally remain constant, or show changes only over a longer period of time. Also note that some of the tests are performed very quickly. For example, the "O2 Sensor Heater Circuit Malfunction" code that haunts Gen II users with aftermarket exhausts (such as myself) actually trips within the first fifteen seconds of operation.

For final reference, the Dodge Service manuals for each respective Viper model year will give the specific details on what each monitor needs to run. Sometimes I wonder how someone came up with all this nonsense!

I understand this... But depending on what machine its hooked to, the readings will be 1 in the same... Not responding, Not ready,etc,etc,etc..

On my 2006 this happened, and it was a blown fuse.

OBD system not ready. HELP!

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