CAT monitor not ready (solved)

joejoeguns

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Jul 18, 2019
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valparaiso,indiana
I know this is my first post but for months I have been reading every post on multiple forums to resolve my CAT monitor not ready problem. While I found many people with the same problem I couldn't find anyone that posted how they resolved the problem. I felt it my duty to post what worked for me to possibly help someone in the future.

The back story is I bought a 99 jeep wrangler 4.0 auto with 85k miles from a gentleman that lived in an area that does not require emissions testing 3 years ago. When I bought the jeep I could not get plates right away because the CAT monitor was not ready. After a bunch of work to it, new 02 sensors,new CAT and new muffler it would still not ready. Many phone calls later I convinced them to sniff test me and it passed clean.

In Indiana we must test every 2 years, so my troubles began again. I new it was running clean so my attention turned to every possible drive cycle and trace I could find on the internet. I took it to a dealer and was told it was a PCM problem and nothing they could do because of it's age.

In a last ditch effort before I either sold it because I couldn't get plates or take it to an emissions shop and paid whatever I had to I tried one more thing.

I started the jeep and let it warm up, shut the jeep off for 10 seconds as per one of the drive cycles I've read (don't know if this is needed but what I did). Then ran it down the highway for only about a mile and a half at 55 mph at 3,000 rpm. BOOM monitor ready. since it's an auto I had to keep it in second gear.

I don't know if this was a fluke, an act of God or a solved mystery drive cycle but it worked for me. I have no science behind it but I hope someone can use this information to ready their troublesome CAT monitor. Thank you to all that posted info I have used in the past.
 
My understanding is that after a vehicle is worked on and the battery has been off it for long enough for the PCM to reset, you sometimes have to drive several hundred miles for the emission systems to be ready again.

Could this have been the issue?
 
Chris, Not at all the case. Since I only test every two years I had over 20,000 miles and 450+ cold starts (confirmed on snap-on shop scanner) since the last PCM reset and the CAT monitor still had not set.
Only recently had I reset the PCM in attempts to force run the monitors. I could easily get all other monitors to ready in 1 day. My feeling is the drive cycles for the CAT monitor are not well documented.
I believe mine set because I ran it at a high RPM and super heated the converter, having nothing to do with the typically posted drive traces you see online. I.E. 45 mph between 1300 and 1900 rpm ........yata,yata,yata. I've tried them all to a maddening extent.
 
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My feeling is the drive cycles for the CAT monitor are not well documented.

It's possible to set all of the monitors in your driveway with the Jeep on jackstands.

Jeep, Chrysler, and Dodge Drive Cycle

For all drive cycles, make sure the check engine light (MIL) is off.

All Monitor Drive Trace

Pre-Conditioning Requirements:

>> MIL must be off

>> Cold start (Note: cold start temperature is undefined)

Driving Procedure :

1) Warm engine up for five minutes (must reach closed loop)

2) Drive (with steady throttle) at a speed between 40 and 60 mph for 8 minutes.

3) Stop and idle for 3 minutes.

4) Drive (with steady throttle) at a speed above 20 mph for 2 minutes.

5) Turn key off, leave off for ten minutes (to run O2 sensor heater monitor).

Note: Due to the limited preconditions provided with this drive trace, NCVECS recommends using the monitor specific drive traces for Chrysler vehicles

https://smogcheckvacaville.com/chrysler-drive-cycle-odb2-readiness-monitors/
 
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Did the jack stand thing and followed every drive trace I could find, didn't work. I'm no expert just letting everyone know what worked for me when all else failed. If you can do it following the common information, lucky you. Not everyone is so lucky. I'm not trying to start anything here just trying to help someone that may have been or is in my boat.
 
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I'm not trying to start anything here just trying to help someone that may have been or is in my boat.

I don't think anyone thinks you're starting anything at all, please don't take it that way.

I was merely just speculating, not trying to challenge you or anything.

I appreciate the update!
 
I had a hard time with my 05 when I went to sell it. Came down to a FSB from 07 where you needed to rewire the ASD and fuel pump relay in the PDC. Seemed kooky but it came straight from DC so I went ahead and did it. About 30 mins, all good to test. Of course this was after driving around like a fool for 3 days and putting on 400 miles :rolleyes:

When I searched for answers there were several different methods of getting certain monitors ready to test similar to the one you used. Most seemed really odd to me but I was never an emissions guys so what do I know 😁
 
Folks - I have the same issue with the CAT monitor on my 06 TJ, it shows not ready state which caused it to fail the NY Emissions inspection. The inspector told me to drive it for some 500 miles before bringing it back for re-inspection. Is this true?

Before taking it for inspection, I had the LDP replaced on my 06 TJ to fix the CEL with a P0456 code. I hope it fixed the issue, the CEL has not
come back after driving it for over 100 miles, but you never know.

Is there a tool that I can buy online to find out if the CAT monitors are ready before taking the jeep back for re-inspection? I don't want to get it re-inspected if they are not ready.

Thanks for all the support
 
Most OBDII readers can tell you the status of the Monitors (except for the cheapest ones, perhaps). There are handheld all-in-one models, and bluetooth scanners for your smart phone, and USB scanners for real computers. I use on OBDlink SX USB scanner with a laptop running OBDwiz software which comes with the scanner.

You can probably tell if it's cleared yet with no tools at all. Turn on your key, but don't start it. If the CEL starts blinking after 15 seconds, there is still something unhappy in the OBD system. If you're pretty sure everything else is good, then it's probably that CAT monitor.
 
Most OBDII readers can tell you the status of the Monitors (except for the cheapest ones, perhaps). There are handheld all-in-one models, and bluetooth scanners for your smart phone, and USB scanners for real computers. I use on OBDlink SX USB scanner with a laptop running OBDwiz software which comes with the scanner.

You can probably tell if it's cleared yet with no tools at all. Turn on your key, but don't start it. If the CEL starts blinking after 15 seconds, there is still something unhappy in the OBD system. If you're pretty sure everything else is good, then it's probably that CAT monitor.

Thank you. I will give it a try and see if the CEL starts blinking after 15 seconds.
 
Thank you. I will give it a try and see if the CEL starts blinking after 15 seconds.

Most OBDII readers can tell you the status of the Monitors (except for the cheapest ones, perhaps). There are handheld all-in-one models, and bluetooth scanners for your smart phone, and USB scanners for real computers. I use on OBDlink SX USB scanner with a laptop running OBDwiz software which comes with the scanner.

You can probably tell if it's cleared yet with no tools at all. Turn on your key, but don't start it. If the CEL starts blinking after 15 seconds, there is still something unhappy in the OBD system. If you're pretty sure everything else is good, then it's probably that CAT monitor.

Yes, the CEL blinked after some 15 seconds and kept blinking for 10 times before staying solid.
 
If it's only the Cat Monitor holding it up, you should be able to run just the Cat Monitor Drive Trace in the drive cycles listed above by LJ. You might have to try it several times to get the conditions just right (temperature, fuel level, timing, etc).
 
Just to give one more piece of information.
I am this guy who had to clear 3 monitors out of 4 in my garage on jack stands, so I can go to inspection ( was rebuilding my Jeep from salvage).
So, I was able to clear consistently everything except the cat one, for which none of the instructions worked. In Texas it is enough to clear 3 out of 4, and you can pass.
I have an article about how I cleared 3. It is very detailed and slightly different from what I have found online. For example you have to be cool weather in order to pass, as ambient have to 75F.
 
Maybe it's time to do TSB 25-001-07 (or the latest incarnation TSB 25-005-13A). That's an official Chrysler fix which changes a couple of wires in the Power Distribution Center under the hood. It rewires the Automatic Shut Down Relay to get power from the battery instead of the ignition switch, which lets the PCM run an extra couple of seconds after the key is switched off. It's for Cat, Oxy, and Oxy Heater Monitor problems. It fixed my O2 Sensor Heater Monitor which had been stuck forever.
 

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Just to give one more piece of information.
I am this guy who had to clear 3 monitors out of 4 in my garage on jack stands, so I can go to inspection ( was rebuilding my Jeep from salvage).
So, I was able to clear consistently everything except the cat one, for which none of the instructions worked. In Texas it is enough to clear 3 out of 4, and you can pass.
I have an article about how I cleared 3. It is very detailed and slightly different from what I have found online. For example you have to be cool weather in order to pass, as ambient have to 75F.

Thank you. I think I have the same issue too. My H02S is also showing "Not Ready". I read the

Jeep TSB 25-005-13 REV. A, bulletin, and the diagnosis section matches exactly what I am noticing on my TJ. I called the dealer to confirm if this issue is covered under warranty and they said yes. Hopefully, this fixes my other issue with EVAP Not Ready as well. If everything goes well, I should get my new inspection sticker.

 
I have the same issue with my 2006 TJ unlimited 4.0 I never had a problem passing a smog check until the battery died. I replaced the battery and performed the TSB wiring. It took 300 miles of driving to get the cat monitor ready. I checked it ready, drove it to the smog shop and they told me that maybe turning on the defroster caused it to not be ready! This is an ongoing problem.
 
I have the same issue with my 2006 TJ unlimited 4.0 I never had a problem passing a smog check until the battery died. I replaced the battery and performed the TSB wiring. It took 300 miles of driving to get the cat monitor ready. I checked it ready, drove it to the smog shop and they told me that maybe turning on the defroster caused it to not be ready! This is an ongoing problem.

How many monitors you can have not ready and still in California? In Texas you can have one monitor still not ready and pass for TJ (it is old vehicles thing I think).