05 STS P0430 (bank 2 cat efficiency)

It's your engine, transmission, driveline
kevm14
Posts: 13935
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS P0430 (bank 2 cat efficiency)

Post by kevm14 » Mon Mar 02, 2020 7:09 am

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
Posts: 13935
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS P0430 (bank 2 cat efficiency)

Post by kevm14 » Mon Mar 02, 2020 7:15 am

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.

kevm14
Posts: 13935
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS P0430 (bank 2 cat efficiency)

Post by kevm14 » 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).

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
Posts: 13935
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS P0430 (bank 2 cat efficiency)

Post by kevm14 » Fri Mar 06, 2020 6:28 pm

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.

kevm14
Posts: 13935
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS P0430 (bank 2 cat efficiency)

Post by kevm14 » Wed Mar 11, 2020 6:24 pm

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

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