Possible damage caused by driving with three bad catalytic converters

WILLPAT100

MEMBER
2012 CHEVROLET IMPALA
3.6L
V6
2WD
AUTOMATIC
14,000 MILES

My engine that dealership rebuilt at 100,000 miles with spun rod bearing. It spun another 32,000 miles later and wouldn't do anything about it. I found a replacement with 12,000 original miles and it wouldn't run right. We figured out the converters were plugged. Dealership replaced bank 1 converter and sent it home. While driving trying to set the monitors it threw another 420 and 430 code took it back they changed bank 2 converter. After driving it more monitors set but threw another set of converter codes. Then they changed 3rd cat in front of where the resonator is located and did a crankshaft relearn. On the way to get it inspected it lost power and began to knock again. It also threw 12 more codes mostly dealing with both exhaust cams over advanced. But no check engine light. At idle there is no knocking starts at about 1500 rpm's. The list of codes are in the car at dealership. Question is, could there poor troubleshooting caused the failures?

7 Replies

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

Direct Trouble Code(DTC) P0420 and P0430 are for catalytic converters that have gone through their life expectancy, and need to be replaced. I don't believe that the shop had any thing to do with camshaft actuators, so I would say no, they didn't do anything wrong. The one thing I find quirky in your question is the fact that 12 DTC's set without the Malfunction Indicator Lamp(MIL) illuminating. How do know that these DTCs set?

Thanks,
Alex
2CarPros

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Monday, September 16th, 2019 AT 4:55 PM

WILLPAT100

MEMBER
9 POSTS

I found this and believe it is the cause but GM says it doesn't exist. Corporate Bulletin
Number 06-06-01-010c, titled close-coupled converter and engine replacement which states the converter material can be sucked into the combustion chamber and lead to engine failure. Does anyone know where I can find this? Here is what I found: Information on Close-Coupled Converter and
Engine Replacement
2016 and Prior GM Passenger Cars and Trucks
with Close-Coupled Catalytic Converters
This Bulletin also applies to any of the above models that may be Export vehicles.
This Bulletin has been revised to add the 2015-2016 Model Years. Please discard Corporate Bulletin
Number 06-06-01-010B.
Certain 2016 and prior General Motors products may be equipped with a new style of catalytic
converter, technically known as the close-coupled catalytic converter, providing quick catalyst
warm-up, resulting in lower tail pipe emissions earlier in the vehicle operating cycle.
If an engine breakdown or non-function were to occur (such as broken intake/exhaust valve or
piston), debris may be deposited in the converter through engine exhaust ports. If the engine is nonfunctioning
due to a severe overheat event, damage to the ceramic “brick” internal to the catalytic
converter may occur. This may result in ceramic debris being drawn into the engine through the
cylinder head exhaust ports.
If a replacement engine is installed in either of these instances, the replacement engine may fail due
to the debris being introduced into the combustion chambers when started.
When replacing an engine for a breakdown or non-function, an inspection of the catalytic converters
and ALL transferred components (such as exhaust/intake manifolds) should be performed. Any
debris found should be removed. In cases of engine failure due to severe overheat, dealers should
also inspect each catalytic converter for signs of melting or cracking of the ceramic “brick.” If
damage is observed, the converter should be replaced.

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Tuesday, October 1st, 2019 AT 12:17 PM

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello again,

I have included the Technical Service Bulletin(TSB) that you were inquiring about in the diagrams down below. Please go through it and get back to us if it helps you out.

Thanks,
Alex
2CarPros

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