Repair-It

The light was off nearly all week last week. It does seem to confirm my theory that warm starts are the issue. Cold starts are fine because the cat warmup routine (probably extra fuel and maybe some spark retard) gets them going, and hot starts are fine because the exhaust doesn't cool down. Warm starts are where the exhaust is too cool to be hot, but the car is too warm for the car to light off the cats (because they're supposed to be working efficiently, obviously).

But this sort of suggests that depending on how you use the car, you could go a very long time not seeing a light or you could get a light all the time. I mean look at my truck. It has NO cat and the light never comes on unless I do a long highway drive.

Not sure why long highway drives also seem to trigger a light in the STS. Only real theories I have are:
1) Lower RPM and high speed means the exhaust probably runs a lot cooler than it does around town
2) Long highway drives may be associated with warm starts somehow? I'd think getting gas would qualify as a hot start though...
3) And I'll throw this in. Long highway drives may present ample and continuous opportunity for the cat efficiency diag routine to run, which means more chances for failure even all things being equal.

I do think long highway drives are the only time I see the light come on while the car has been driving for a while. In my normal usage, it will always come on within like 2 minutes of a ignition cycle and usually a cold start, which tells me it was setting the criteria for the light on the previous ignition cycle. It's a little confusing what is actually happening. What I'm saying is if I scanned it constantly, I'd see a pending code for P0430 before I saw the actual light and I am not sure exactly HOW early I'd see that.

None of this REALLY matters though. Still would like to program out the code. And at this point, even if I remove the manifold and cat to do the mounts, I think I will put it right back on there, at $475....

kevm14 wrote: ↑Mon Mar 02, 2020 7:09 am Not sure why long highway drives also seem to trigger a light in the STS. Only real theories I have are:
...
3) And I'll throw this in. Long highway drives may present ample and continuous opportunity for the cat efficiency diag routine to run, which means more chances for failure even all things being equal.

Here is the criteria for the diag routine from the first page:

Conditions for Running the DTC
• DTCs P0010, P0011, P0013, P0014, P0016, P0017, P0018, P0019, P0020, P0023, P0024, P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, P0058, P0068, P0102, P0103, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0151, P0153, P0155, P0157, P0158, P0159, P0160, P0161, P0171, P0172, P0174, P0175, P0221, P0222, P0223, P0300-P0308, P0315, P0335, P0336, P0340, P0341, P0345, P0346, P0365, P0366, P0390, P0391, P0500, P0608, P1137, P1138, P1157, P1258, P1358, P1380, P1381, P2088, P2090-P2095, P2101, P2119, P2135, P2231, or P2234 are not set.

• The mass air flow (MAF) is between 11-80.3 grams per second.

• The engine speed is between 1,088-3,008 RPM.

• The engine has been running more than 10 minutes.

• The predicted catalyst temperature is between 644-902°C (1,191-1,656°F).

• The barometric pressure (BARO) is more than 74 kPa.

• The engine coolant temperature (ECT) is more than 62°C (143°F).

• The intake air temperature (IAT) is between -6°C and +200°C (+21°F and +392°F).

• The engine is in Closed Loop fuel control.

• The vehicle speed sensor (VSS) is more than 35 km/h (22 mph).

• The engine is at a steady cruise, a light load, with no load variation.

• DTC P0420 and P0430 run once within the above conditions are met for 24.8 seconds.

The last three basically amplify my third theory. Over 22 mph (no lights or stop signs), steady cruise with no load variation (something much more likely on the highway), mass airflow between 11 and 80.3 g/sec (also the meat of where it would be on the highway) and it has to HOLD these conditions (all the listed conditions above) for almost 25 seconds before it will even run the diag.

BUT...the light will always go out on its own. Which means it is actually passing the diag routine, or else the light would not go out. And I don't know how many times it has to pass before it will turn the light off, either. It may not be just once. Interesting.

Light is off already. I think yesterday morning. That was really fast. I pick Ian up from an activity tonight so there will be a hot restart (~10-12 min soak after driving 30 mins).

Self-healing catalyst? Like, I could have brought it in to be inspected any day last week, or right now, and it would pass no problem I'm sure.

Still hate looking at the damn light though. I always feel like people next to me can see it.

kevm14 wrote: ↑Tue Mar 03, 2020 6:55 am Light is off already. I think yesterday morning. That was really fast. I pick Ian up from an activity tonight so there will be a hot restart (~10-12 min soak after driving 30 mins).

Interesting. Light never came on and I got gas, too (extra cycles). Another activity Thursday night. No light still.

Light back on finally. Of course I didn't drive it for 2 days.

The light has been on this whole time. Of course I haven't been commuting with it.

Randomly, I ordered this:
https://www.amazon.com/dp/B00AQ7972O/re ... bFb2PT7FZ1

It could work because the chamber/isolation from the cat traps exhaust oxygen and can trick the computer into thinking the cat is storing oxygen correctly which is how the diagnostic routine works.

Just received this. Apparently it was on the slow boat. 7 days, what is this, the 90s?
Nice TIG welds.

I put the smallest pellet in for maximum cheating. I also shimmed it with some aluminum foil since it is loose in there. Obviously stuff expands but one guy commented that it caused false knock on his car. I don't need any of that BS. Shouldn't rattle now. But yeah, small pellet and snap ring. Hopefully there is enough clearance under there to fit this 90 degree elbow. Also I hope I am able to remove the sensor without ruining the threads. I will have to install the elbow first, tighten the jamb nut, and then install my sensor on the elbow. What could go wrong?

Fail. Couldn't get the O2 loose. I wouldn't say I tried as if my life depended on it but I think if I am serious about completing this job (installing the elbow) I ought to have a new O2 sensor in hand because I don't see how the threads of the old one will survive after I apply as much torque as it seems to require. I did torch it, too and pulled about as hard as I could on my open end wrench.

So I sort of gave up for now. A tune would be easier for sure...but still no availability.

Been resetting the light again when I drive the car because if my E55 doesn't have a chronic CEL, I'm damn well not going to stare at the yellow glow on my STS.

It has come back quickly more often than not but this time has been out for a few drive cycles. Last night when I got home I scanned it. All systems ready, no CEL. However, I checked for pending codes and sure enough the P0430 was sitting there. Not sure if it will simply turn on next drive cycle, typically a couple minutes into the ignition cycle. Probably yes.

I do think it may still be possible to pass inspection after a well-timed reset but it's only getting more dicey with time/miles.

kevm14 wrote: ↑Fri Nov 13, 2020 3:36 pm However, I checked for pending codes and sure enough the P0430 was sitting there. Not sure if it will simply turn on next drive cycle, typically a couple minutes into the ignition cycle. Probably yes.

Yes indeed. CEL came on as predicted.