Repair-It

Code popped up again Friday morning - forgot to post. Reset last night with generic tool.

Hopefully this tapers back down in the warmer weather but I think in general this is going to slowly get worse as the performance of the cat continues to degrade. Hoping to get through my inspection in May by playing code reset games, which will buy me 2 more years to deal with this or even fix it. Wish I could just program the code out but no joy on the 04-05 LH2 with one-off ECM.

It has never set a P0420 which is Bank 1 (passenger side). But I don't know what that means. Like not sure if the P0430 pops up and then it can no longer set a P0420 until the P0430 is cleared. I think I posted the FSM page on it and it would state that if true. Anyway, that would mean that I could replace the Bank 2 cat, and it could open up the chance of setting a P0420 now that the P0430 isn't "blocking" it. Standby...

EDIT: Alright ignore that. There is a LONG list of DTCs that will prevent a P0420 from setting but a P0430 is not one of them.

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.

So, given that I've never once seen a P0420 I probably would NOT preemptively replace that, unless I really thought it was "easy" once the car is taken apart enough to do the driver's side. But other than disconnecting the catback exhaust, I don't think there is much shared between the two jobs. There are totally different interference items, not surprisingly.

So probably against my better judgement I ordered this on the recommendation from someone on the Caddy forum:
https://www.amazon.com/gp/product/B01LF ... UTF8&psc=1

I figured it can't hurt and I did seem to have a little luck with Techron so perhaps a targeted product may actually do something? Also I think he said he has gone 3,000 miles with no code after using the product...

Can't hurt anyway.

Safe and effective for all petrol (gasoline), diesel and hybrid vehicles
Engineered to clean the entire exhaust system with regular use
OXICAT is activated when the catalytic converter reaches its required working temperature.
Proven safe and effective by the Pros, now available in North America. TUV certified, made in Germany

Important information
Legal Disclaimer
OXICAT requires the vehicle to reach and sustain the working temperature of the catalytic converter. If the catalytic converter is cracked, damaged or completely clogged, OXICAT will NOT function properly.

Product description
With an innovative new decarbonizing technology OXICAT cleans the entire exhaust system, dissolving soot and carbon deposits throughout. TO BE EFFECTIVE, OXICAT REQUIRES THE VEHICLE TO REACH AND SUSTAIN THE WORKING TEMPERATURE OF THE CATALYTIC CONVERTER. Used regularly, OXICAT is ideal to help prevent the buildup of noxious residue that can cause a vehicle to fail required emissions tests. It is specifically engineered to meet or exceed recent environmental standards, protecting both your vehicle and the environment. OXICAT is specifically engineered to be used as part of a proactive care plan to optimize vehicle performance and engine life. It is NOT a "mechanic-in-a-can" and is not engineered to repair vehicle exhaust systems.

The last part seems quite honest. Either that or the EU probably has strict rules about product claims so the caveats need to be clearly worded and direct.

They also sell this: https://www.amazon.com/AUTOPROFI-Intens ... B07DHWRD5Y

Targeted toward diesel DPF applications but says also will do gasoline catalysts. I suspect you have to remove the front O2 and spray this downstream, let it soak and then drive the car.

So the light came back on after I got gas this week but before I could post, the plot thickened. It was off this morning. That has never happened. I should scan to see if it was really a P0430. The funny thing about this, though, is that I considered adding that German additive for the cat. But I did not. Imagine if I did! I would have certainly credited it. But like I said let me check which code it was before I get too liquored up here...

And the light is back on after Jamie borrowed the car while her tire was at the shop. This is not the first time she's returned the car with the light on. lol

Still haven't scanned though. Too....cold?

Made it through the entire weekend without scanning...light is still on.

This is one more reason that neglected cars end up with compound problems. I already expect the light to be on given my cat issue. But I am heavily desensitized to it so another issue (perhaps one more pressing) may go unnoticed. I mean the cat issue is important for basically two reasons:
1) One possible failure mode of a cat is to either clog or break apart causing excessive exhaust backpressure, impacting drivability, fuel economy, and in extreme cases, can cause engine damage
2) Inspection deficiency
2a) Emissions something something blah blah blah

Most P-codes are more consequential than that. I guess another good example of a minor one would be like small evap leak.

But anything related to a primary engine control is nothing to ignore, and by that I mean any sensor or actuator that impacts engine airflow, fueling or spark control.

Light went out again. Lol

Still haven't scanned. I'm terrible.

Going to add my German liquid stuff tonight with a fuel-up. Low Fuel is indicated so it's down there. Unlike previous GM cars, there is still some reserve at that point, like even in the ~2 gallon range. Other fun fact: this car has a saddle tank that straddles the driveshaft, just like my other Cadillacs, which means there is a transfer pump to move fuel from the secondary one to the main one with the pickup. Also, there are two fuel level senders and I can see the status of them individually on the Tech 2. So the indicated level is basically the average.

Actually if it is a 17.5 gallon tank then I only had 1 gallon left. I did scan it with my generic tool and it just confused me. I scanned the first module and nothing was there. There is one other module that it lets me scan that says "Engine" and it had both a current and history code for P0430. Yet the light was off my whole ride home. Was it about to throw the light on the next ignition cycle? So confused. We'll see tomorrow morning.

Light was NOT on this morning. Interesting. Maybe I should have scanned it running? Or maybe I should upgrade to a better generic tool. Or use the Tech 2 that I have...