OBDII Monitors - Catalyst ready, but O2 not ready?

Subject is a 2012 Dodge Grand Caravan, 131k miles- I cleared a code a couple weeks back due to a self-loosening gas cap, and have driven it under a wide variety of different operating conditions since then. Never seen any other codes present themselves aside from the gas cap EVAP code.

Checking with Torque Lite, I see all emissions readiness monitors are set, except the O2 sensor monitor. Both catalyst and O2 heater monitors are set. They won't even test it for emissions here with that last monitor showing not ready (just tried today). 

Can anyone enlighten me on how this could not be set, even though the computer is happy enough with the O2 sensor function to set the catalyst monitor? There are two upstream and two downstream sensors; one cat for each bank right at the exhaust manifold outlet. 

Suppose I need a real scan tool to see live data from the sensors to understand which one or multiple might be less than happy? I'm tempted to throw four new sensors at it because at $140 total I could easily exceed that in diagnostic costs at a dealership, but don't want to fire the parts cannon if I don't have to.

What size engine, 3.0 or 3.8?

In reply to Donebrokeit :

2012 is 3.6 Pentastar.

The reason that some monitors have run and others have not is that they operate under different conditions.  Like I'm aware of one brand that runs the O2 monitor at 40-55 mph but the catalyst monitor is run during a deceleration.  And they don't have to clear before the same sensors are used to test another component- like the O2 sensor and the catalyst monitor.

Does anyone have Chrysler-specific experience or access to a shop manual; perhaps there is a written drive cycle procedure to run the O2 sensor monitors? I'm having a hard time finding emissions monitor drive cycle info online. 

Just annoying that it could still be incomplete; I've been driving the car under a very wide variety of operating conditions for a couple weeks now so I should have hit any necessary parameter by now.

Found this on the intarwebs.  Does this help?

All Monitor Drive Trace
Idle for 5 minutes
Warm engine up for five minutes
Smoothly acceerate and maintain a speed between 40 to 60 mph for 8 minutes.
Stop and idle for 3 minutes.
Smoothly accelerate and maintain a speed above 20 mph for 2 minutes.
Turn key off, leave off for ten minutes

Catalyst Monitor Drive Trace
Idle for 5 minutes
Smoothly accelerate and maintain a speed between 30 to 45 mph for 2 minutes.

EGR System Monitor Drive Trace – Vacuum controlled
Idle for 5 minutes
Smoothly accelerate and maintain a speed between 40 to 60 mph for 2 minutes.

EGR System Monitor Drive Trace – Electronic
Idle for 5 minutes
Smoothly accelerate and maintain a speed between 40 to 60 mph for 2 minutes.
Idle for 3 minutes

Evaporative System Monitor Drive Trace
Trace 1: Standard Type – Make sure that your fuel level is between 50% and 85% full.
Idle for 5 minutes
Smoothly accelerate and maintain a speed between 30 to 45 mph for 2 minutes.

Trace 2: Leak Detection Pump
From 6-8 hours of the vehicle being off (cold soak), idle for 5 minutes
Drive in city traffic naturally with stops and acceleration for 5 minutes.
Stop. Idle vehicle for 4 minutes.

O2 Sensor Monitor Drive Trace
Idle for 5 minutes
Smoothly accelerate and maintain a speed above 25 mph for 2 minutes.
Stop and idle for 30 seconds.
Smoothly accelerate and maintain a speed between 30 to 40 mph
Repeat idle and acceleration to 30-40 mph five times.

O2 Sensor Heater Monitor Drive Trace
Idle for 5 minutes, then shut the engine and leave the vehicle off for 10 minutes.

That was from this: cdci (neons.org)

Completely different, unrelated vehicles: I had a Miata that had similar symptoms. Cleaning the EGR valve fixed it for me, even though it took 3+ months to finally throw a code. If one is not running/ready, it will often stop others downstream (or at least downstream in the algorithm) from running. So figure out where the bottleneck is and fix that. It may or may not be directly related to the O2 and catalyst.

newrider3 said:

Does anyone have Chrysler-specific experience or access to a shop manual; perhaps there is a written drive cycle procedure to run the O2 sensor monitors? I'm having a hard time finding emissions monitor drive cycle info online. 

Just annoying that it could still be incomplete; I've been driving the car under a very wide variety of operating conditions for a couple weeks now so I should have hit any necessary parameter by now.

Drive this cycle- https://en.wikipedia.org/wiki/FTP-75

That's the one that over two cycles (as a prep) every car is required to run, and complete, every monitor.  Many of them will get tested in the 45-55mph area at ~300 seconds into the cold cycle.

mtn said:

Completely different, unrelated vehicles: I had a Miata that had similar symptoms. Cleaning the EGR valve fixed it for me, even though it took 3+ months to finally throw a code. If one is not running/ready, it will often stop others downstream (or at least downstream in the algorithm) from running. So figure out where the bottleneck is and fix that. It may or may not be directly related to the O2 and catalyst.

Unless the test is a basic life test (is the circuit good, is there a sensor attached), there should not be an interruption in any monitor if other monitors don't complete their test.  The tests should be independent of each other, so that THE specific failure can be found, and not miss others.

alfadriver said:

mtn said:

Completely different, unrelated vehicles: I had a Miata that had similar symptoms. Cleaning the EGR valve fixed it for me, even though it took 3+ months to finally throw a code. If one is not running/ready, it will often stop others downstream (or at least downstream in the algorithm) from running. So figure out where the bottleneck is and fix that. It may or may not be directly related to the O2 and catalyst.

Unless the test is a basic life test (is the circuit good, is there a sensor attached), there should not be an interruption in any monitor if other monitors don't complete their test.  The tests should be independent of each other, so that THE specific failure can be found, and not miss others.

Hey, that could be how it is designed to work and is supposed to work. And it could be how it was working in mine. But my experience is that it doesn't always work that way, or there was something else going on. The only thing I changed was cleaning the EGR valve and swapping the hoses associated with it. All of a sudden, within 20 miles, 5 different monitors were showing emissions ready after over 3oo miles of them not. 

Of course, comparing 1996 OBDII to 2012 OBDII is exceptionally silly.

In reply to alfadriver :

I still can't wrap my head around how they can claim to run catalyst monitor before the O2 monitors have run.  You don't know the O2s' integrity at that point.

I mean, I'll roll with it, because that's the testing that we're studying for, so to speak.

And yes, this HAS bitten in the ass before.  I had a 3.8 Caravan that had an EGR position sensor failure, like they all do.  Replaced the valve assembly and the codes came back.  Turns out, there is an adaptive that you can only reset by disconnecting the battery.  How cheesy.  So I do this, and a week later the vehicle comes back with a P0420.  Now, the vehicle had been passing the catalyst monitor before the EGR failure, and I don't much believe in coincidence.  What I do know is that Chrysler monitors oxygen sensor drift in the time between the O2s lighting off and the catalyst lighting off.  Figuring that one or both O2s had drifted, and were too far out of spec for the computer to re-learn them after the equivalent of resetting all adaptives with a sledgehammer, I replaced both O2s.  It ran and passed the catalyst monitor after that...

Well, the intrusive O2 test really tests how accurate it is, whereas the catalyst test just compares the front to rear sensor- so the accuracy isn't quite that important...  Different requirements.  That, and some modern catalyst tests only need the rear sensor, and not the front one.  I don't think there's an intrusive rear O2 sensor test- as it barely ages over time.  Ok, that's a little bit of an exaggeration, but the front only confirms that fresh air is going into the catalyst- but it does almost nothing else for the catalyst monitor.

Oddly enough, the O2 sensor test generally happens before the catalyst test, but that's just because of the timing of the cycle.

In reply to alfadriver :

This particular example was definitely older tech than anything in the past, oh, 20 years   Chrysler loves to hang on to status quo.  V6 with the exhaust from the left (front) bank running into the right (rear) bank, so it only had one upstream oxygen sensor, and it was narrowband.  I don't think they went to separate banks on pushrod V6s ever.

That said, I also had a couple weeks ago a 4 liter Toyota truck that was setting a '420 and '430, at roughly 100k, with no history of oil consumption, coolant use, or misfires.  It had UEGOs upstream.  Replacing all four sensors made the computer happy with the catalysts' performance. 

In either case, I figure that the sensors had drifted enough that what they were reporting as stoich, wasn't, and thus poor catalyst efficiency.  I always prefer to replace upstream and downstream as a set, for this reason.